All Questions Flashcards by Rhoan Jane Altura Calunsag

Which formula correctly describes the relationship between absorbance and %T ?

A. A = 2 - log %T
B. A = log 1/T
C. A = -log T
D. All of these options

D. All of these options

How well did you know this?

Not at all

Perfectly

A solution that has a transmittance of 1.0 %T would have an absorbance of:

A. 1.0
B. 2.0
C. 1%
D. 99%

B. 2.0

How well did you know this?

Not at all

Perfectly

In absorption spectrophotometry:

A. Absorbance is directly proportional to
transmittance
B. Percent transmittance is directly proportional to concentration
C. Percent transmittance is directly proportional to the light path length
D. Absorbance is directly proportional to concentration

D. Absorbance is directly proportional to concentration

How well did you know this?

Not at all

Perfectly

Which wavelength would be absorbed strongly by a red-colored solution?

A. 450 nm
B. 585 nm
C. 600 nm
D. 650 nm

A. 450 nm

How well did you know this?

Not at all

Perfectly

A green-colored solution would show highest transmittance at:

A. 475 nm
B. 525 nm
C. 585 nm
D. 620 nm

B. 525 nm

How well did you know this?

Not at all

Perfectly

SITUATION: A technologist is performing an enzyme assay at 340 nm using a visible-range spectrophotometer. After setting the wavelength and adjusting the readout to zero %T with the light path blocked, a cuvette with deionized water is inserted. With the light path fully open and the 100%T control at maximum, the instrument readout will not rise above 90%T. What is the most appropriate first course of action?

A. Replace the source lamp
B. Insert a wider cuvette into the light path
C. Measure the voltage across the lamp terminals
D. Replace the instrument fuse

A. Replace the source lamp

How well did you know this?

Not at all

Perfectly

Which type of monochromator produces the purest monochromatic light in the UV range?

A. A diffraction grating and a fixed exit slit
B. A sharp cutoff filter and a variable exit slit
C. Interference filters and a variable exit slit
D. A prism and a variable exit slit

D. A prism and a variable exit slit

How well did you know this?

Not at all

Perfectly

Which monochromator specification is required in order to measure the true absorbance of a compound having a natural absorption bandwidth of 30 nm?

A. 50-nm bandpass
B. 25-nm bandpass
C. 15-nm bandpass
D. 5-nm bandpass

D. 5-nm bandpass

How well did you know this?

Not at all

Perfectly

Which photodetector is most sensitive to low levels of light?

A. Barrier layer cell
B. Photodiode
C. Diode array
D. Photomultiplier tube

D. Photomultiplier tube

How well did you know this?

Not at all

Perfectly

Which condition is a common cause of stray light?

A. Unstable source lamp voltage
B. Improper wavelength calibration
C. Dispersion from second-order spectra
D. Misaligned source lamp

C. Dispersion from second-order spectra

How well did you know this?

Not at all

Perfectly

A linearity study is performed on a visible spectrophotometer at 650 nm and the following absorbance readings are obtained:

Concentration of Standard
10.0 mg/dL
20.0 mg/dL
30.0 mg/dL
40.0 mg/dL
50.0 mg/dL
Absorbance
0.20
0.41
0.62
0.79
0.92
The study was repeated using freshly prepared standards and reagents, but results were identical to those shown. What is the most likely cause of
these results?

A. Wrong wavelength used
B. Insufficient chromophore concentration
C. Matrix interference
D. Stray light

D. Stray light

How well did you know this?

Not at all

Perfectly

Which type of filter is best for measuring stray light?

A. Wratten
B. Didymium
C. Sharp cutoff
D. Neutral density

C. Sharp cutoff

How well did you know this?

Not at all

Perfectly

Which of the following materials is best suited for verifying the wavelength calibration of a spectrophotometer?

A. Neutral density filters
B. Potassium dichromate solutions traceable to the National Bureau of Standards reference
C. Wratten filters
D. Holmium oxide glass

D. Holmium oxide glass

How well did you know this?

Not at all

Perfectly

Why do many optical systems in chemistry analyzers utilize a reference light path?

A. To increase the sensitivity of the measurement
B. To minimize error caused by source lamp fluctuation
C. To obviate the need for wavelength adjustment
D. To reduce stray light effects

B. To minimize error caused by source lamp fluctuation

How well did you know this?

Not at all

Perfectly

Which component is required in a spectrophotometer in order to produce a spectral absorbance curve?

A. Multiple monochromators
B. A reference optical beam
C. Photodiode array
D. Laser light source

C. Photodiode array

How well did you know this?

Not at all

Perfectly

The half-band width of a monochromator is defined by:

A. The range of wavelengths passed at 50% maximum transmittance
B. One-half the lowest wavelength of optical purity
C. The wavelength of peak transmittance
D. One-half the wavelength of peak absorbance

A. The range of wavelengths passed at 50% maximum transmittance

How well did you know this?

Not at all

Perfectly

The reagent blank corrects for absorbance caused by:

A. The color of reagents
B. Sample turbidity
C. Bilirubin and hemolysis
D. All of these options

A. The color of reagents

How well did you know this?

Not at all

Perfectly

A plasma sample is hemolyzed and turbid. What is required to perform a sample blank in order to correct the measurement for the intrinsic absorbance of the sample when performing a spectrophotometric assay?

A. Substitute deionized water for the sample
B. Dilute the sample 1:2 with a standard of known concentration
C. Substitute saline for the reagent
D. Use a larger volume of the sample

C. Substitute saline for the reagent

How well did you know this?

Not at all

Perfectly

Which instrument requires a highly regulated DC power supply?

A. A spectrophotometer with a barrier layer cell
B. A colorimeter with multilayer interference filters
C. A spectrophotometer with a photomultiplier tube
D. A densitometer with a photodiode detector

C. A spectrophotometer with a photomultiplier tube

How well did you know this?

Not at all

Perfectly

Which statement regarding reflectometry is true?

A. The relation between reflectance density and concentration is linear
B. Single-point calibration can be used to determine concentration
C. 100% reflectance is set with an opaque film called a white reference
D. The diode array is the photodetector of choice

C. 100% reflectance is set with an opaque film called a white reference

How well did you know this?

Not at all

Perfectly

Bichromatic measurement of absorbance can correct for interfering substances if:

A. The contribution of the interferent to absorbance is the same at both wavelengths
B. Both wavelengths pass through the sample simultaneously
C. The side band is a harmonic of the primary wavelength
D. The chromogen has the same absorbance at both wavelengths

A. The contribution of the interferent to absorbance is the same at both wavelengths

How well did you know this?

Not at all

Perfectly

Which instrument requires a primary and secondary monochromator?

A. Spectrophotometer
B. Atomic absorption spectrophotometer
C. Fluorometer
D. Nephelometer

C. Fluorometer

How well did you know this?

Not at all

Perfectly

Which of the following statements about fluorometry is accurate?

A. Fluorometry is less sensitive than spectrophotometry
B. Fluorometry is less specific than spectrophotometry
C. Unsaturated cyclic molecules are often fluorescent
D. Fluorescence is directly proportional to temperature

C. Unsaturated cyclic molecules are often fluorescent

How well did you know this?

Not at all

Perfectly

Which of the following components is not needed in a chemiluminescent immunoassay analyzer?

A. Source lamp
B. Monochromator
C. Photodetector
D. Wash station

A. Source lamp

How well did you know this?

Not at all

Perfectly

Which substance is used to generate the light signal in electrochemiluminescence?

A. Acridinium
B. Luminol
C. Dioxetane phosphate
D. Ruthenium

D. Ruthenium

How well did you know this?

Not at all

Perfectly

Light scattering when the wavelength is greater than 10 times the particle diameter is described by:

A. Rayleigh’s law
B. Te Beer-Lambert law
C. Mie’s law
D. Te Rayleigh-Debye law

A. Rayleigh’s law

How well did you know this?

Not at all

Perfectly

Which statement regarding nephelometry is true?

A. Nephelometry is less sensitive than absorption spectrophotometry
B. Nephelometry follows Beer’s law
C. The optical design is identical to a turbidimeter except that a HeNe laser light source is used
D. The detector response is directly proportional to concentration

D. The detector response is directly proportional to concentration

How well did you know this?

Not at all

Perfectly

The purpose of the nebulizer in an atomic absorption spectrophotometer that uses a flame is to:

A. Convert ions to atoms
B. Cause ejection of an outer shell electron
C. Reduce evaporation of the sample
D. Burn off organic impurities

A. Convert ions to atoms

How well did you know this?

Not at all

Perfectly

A flameless atomic absorption spectrophotometer dehydrates and atomizes a sample using:

A. A graphite capillary furnace
B. An electron gun
C. A thermoelectric semiconductor
D. A thermospray platform

A. A graphite capillary furnace

How well did you know this?

Not at all

Perfectly

When measuring lead in whole blood using atomic absorption spectrophotometry, what reagent is required to obtain the needed sensitivity and precision?

A. Lanthanum
B. Lithium
C. Triton X-100
D. Chloride

C. Triton X-100

How well did you know this?

Not at all

Perfectly

Interference in atomic absorption spectrophotometry caused by differences in viscosity is called:

A. Absorption interference
B. Matrix effect
C. Ionization interference
D. Quenching

B. Matrix effect

How well did you know this?

Not at all

Perfectly

All of the following are required when measuring magnesium by atomic absorption spectrophotometry except:

A. A hollow cathode lamp with a magnesium cathode
B. A chopper to prevent optical interference from magnesium emission
C. A monochromator to isolate the magnesium emission line at 285 nm
D. A 285-nm reference beam to correct for background absorption

D. A 285-nm reference beam to correct for background absorption

How well did you know this?

Not at all

Perfectly

When measuring calcium by atomic absorption spectrophotometry, which is required?

A. An organic extraction reagent to deconjugate calcium from protein
B. An internal standard
C. A magnesium chelator
D. Lanthanum oxide to chelate phosphates

D. Lanthanum oxide to chelate phosphates

How well did you know this?

Not at all

Perfectly

Ion selective analyzers using undiluted samples have what advantage over analyzers that use a diluted sample?

A. Can measure over a wider range of concentration
B. Are not subject to pseudohyponatremia caused by high lipids
C. Do not require temperature equilibration
D. Require less maintenance

B. Are not subject to pseudohyponatremia caused by high lipids

How well did you know this?

Not at all

Perfectly

Select the equation describing the potential that develops at the surface of an ion-selective electrode.

A. van Deemter equation
B. van Slyke equation
C. Nernst equation
D. Henderson-Hasselbalch equation

D. Henderson-Hasselbalch equation

How well did you know this?

Not at all

Perfectly

The reference potential of a silver-silver chloride electrode is determined by the:

A. Concentration of the potassium chloride filling solution
B. Surface area of the electrode
C. Activity of total anion in the paste covering the electrode
D. The concentration of silver in the paste covering the electrode

A. Concentration of the potassium chloride filling solution

How well did you know this?

Not at all

Perfectly

The term RT/nF in the Nernst equation defines the:

A. Potential at the ion-selective membrane
B. Slope of the electrode
C. Decomposition potential
D. Isopotential point of the electrode

B. Slope of the electrode

How well did you know this?

Not at all

Perfectly

The ion-selective membrane used to measure potassium is made of:

A. High-borosilicate glass membrane
B. Polyvinyl chloride dioctylphenyl phosphonate ion exchanger
C. Valinomycin gel
D. Calomel

C. Valinomycin gel

How well did you know this?

Not at all

Perfectly

The response of a sodium electrode to a 10-fold increase in sodium concentration should be:

A. A 10-fold drop in potential
B. An increase in potential of approximately 60 mV
C. An increase in potential of approximately 10 mV
D. A decrease in potential of approximately 10 mV

B. An increase in potential of approximately 60 mV

How well did you know this?

Not at all

Perfectly

Which of the electrodes below is a currentproducing (amperometric) rather than a voltage-producing (potentiometric) electrode?

A. Clark electrode
B. Severinghaus electrode
C. pH electrode
D. Ionized calcium electrode

A. Clark electrode

How well did you know this?

Not at all

Perfectly

Which of the following would cause a “response” error from an ion-selective electrode for sodium when measuring serum but not the calibrator?

A. Interference from other electrolytes
B. Protein coating the ion-selective membrane
C. An overrange in sodium concentration
D. Protein binding to sodium ions

B. Protein coating the ion-selective membrane

How well did you know this?

Not at all

Perfectly

In polarography, the voltage needed to cause depolarization of the cathode is called the:

A. Half-wave potential
B. Isopotential point
C. Decomposition potential
D. Polarization potentia

C. Decomposition potential

How well did you know this?

Not at all

Perfectly

Persistent noise from an ion selective electrode is most often caused by:

A. Contamination of sample
B. Blocked junction at the salt bridge
C. Overrange from high concentration
D. Improper calibration

B. Blocked junction at the salt bridge

How well did you know this?

Not at all

Perfectly

Which element is reduced at the cathode of a Clark polarographic electrode?

A. Silver
B. Oxygen
C. Chloride
D. Potassium

B. Oxygen

How well did you know this?

Not at all

Perfectly

Which of the following statements accurately characterizes the coulometric titration of chloride?

A. The indicator electrodes generate voltage
B. Constant current must be present across the generator electrodes
C. Silver ions are formed at the generator cathode
D. Chloride concentration is inversely proportional to titration time

B. Constant current must be present across the generator electrodes

How well did you know this?

Not at all

Perfectly

In the coulometric chloride titration:

A. Acetic acid in the titrating solution furnishes the counter ion for reduction
B. The endpoint is detected by amperometry
C. The titrating reagent contains a phosphate buffer to keep pH constant
D. Nitric acid (HNO3) is used to lower the solubility of AgCl

B. The endpoint is detected by amperometry

How well did you know this?

Not at all

Perfectly

Which of the following compounds can interfere with the coulometric chloride assay?

A. Bromide
B. Ascorbate
C. Acetoacetate
D. Nitrate

A. Bromide

How well did you know this?

Not at all

Perfectly

All of the following compounds contribute to the osmolality of plasma except:

A. Lipids
B. Creatinine
C. Drug metabolites
D. Glucose

A. Lipids

How well did you know this?

Not at all

Perfectly

One mole per kilogram H2O of any solute will cause all of the following except:

A. Lower the freezing point by 1.86°C
B. Raise vapor pressure by 0.3 mm Hg
C. Raise the boiling point by 0.52°C
D. Raise osmotic pressure by 22.4 atm

B. Raise vapor pressure by 0.3 mm Hg

How well did you know this?

Not at all

Perfectly

What component of a freezing point osmometer measures the sample temperature?

A. Thermistor
B. Thermocouple
C. Capacitor
D. Electrode

A. Thermistor

How well did you know this?

Not at all

Perfectly

What type of measuring circuit is used in a freezing point osmometer?

A. Electrometer
B. Potentiometer
C. Wheatstone bridge
D. Thermal conductivity bridge

C. Wheatstone bridge

How well did you know this?

Not at all

Perfectly

Which measurement principle is employed in a vapor pressure osmometer?

A. Seebeck
B. Peltier
C. Hayden
D. Darlington

A. Seebeck

How well did you know this?

Not at all

Perfectly

The freezing point osmometer differs from the vapor pressure osmometer in that only the freezing point osmometer:

A. Cools the sample
B. Is sensitive to ethanol
C. Requires a thermoelectric module
D. Requires calibration with aqueous standards

B. Is sensitive to ethanol

How well did you know this?

Not at all

Perfectly

The method for measuring iron or lead by plating the metal and then oxidizing it is called:

A. Polarography
B. Coulometry
C. Anodic stripping voltometry
D. Amperometry

C. Anodic stripping voltometry

How well did you know this?

Not at all

Perfectly

The term isocratic is used in high-performance liquid chromatography (HPLC) to mean the:

A. Mobile phase is at constant temperature
B. Stationary phase is equilibrated with the mobile phase
C. Mobile phase consists of a constant solvent composition
D. Flow rate of the mobile phase is regulated

C. Mobile phase consists of a constant solvent composition

How well did you know this?

Not at all

Perfectly

The term reverse phase is used in HPLC to indicate that the mobile phase is:

A. More polar than the stationary phase
B. Liquid and the stationary phase is solid
C. Organic and the stationary phase is aqueous
D. A stronger solvent than the stationary phase

A. More polar than the stationary phase

How well did you know this?

Not at all

Perfectly

What is the primary means of solute separation in HPLC using a C18 column?

A. Anion exchange
B. Size exclusion
C. Partitioning
D. Cation exchange

C. Partitioning

How well did you know this?

Not at all

Perfectly

The most commonly used detector for clinical gas-liquid chromatography (GLC) is based upon:

A. Ultraviolet light absorbance at 254 nm
B. Flame ionization
C. Refractive index
D. Thermal conductance

B. Flame ionization

How well did you know this?

Not at all

Perfectly

What type of detector is used in high-performance liquid chromatography with electrochemical detection (HPLC-ECD)?

A. Calomel electrode
B. Conductivity electrode
C. Glassy carbon electrode
D. Polarographic electrode

C. Glassy carbon electrode

How well did you know this?

Not at all

Perfectly

In gas chromatography, the elution order of volatiles is usually based upon the:

A. Boiling point
B. Molecular size
C. Carbon content
D. Polarity

A. Boiling point

How well did you know this?

Not at all

Perfectly

Select the chemical that is used in most HPLC procedures to decrease solvent polarity.

A. Hexane
B. Nonane
C. Chloroform
D. Acetonitrile

D. Acetonitrile

How well did you know this?

Not at all

Perfectly

In thin-layer chromatography (TLC), the distance the solute migrates divided by the distance the solvent migrates is the:

A. tR
B. Kd
C Rf
D. pK

C Rf

How well did you know this?

Not at all

Perfectly

Which reagent is used in thin-layer chromatography (TLC) to extract cocaine metabolites from urine?

A. Acid and sodium chloride
B. Alkali and organic solvent
C. Chloroform and sodium acetate
D. Neutral solution of ethyl acetate

B. Alkali and organic solvent

How well did you know this?

Not at all

Perfectly

What is the purpose of an internal standard in HPLC and GC methods?

A. To compensate for variation in extraction and injection
B. To correct for background absorbance
C. To compensate for changes in flow rate
D. To correct for coelution of solutes

A. To compensate for variation in extraction and injection

How well did you know this?

Not at all

Perfectly

What is the confirmatory method for measuring drugs of abuse?

A. HPLC
B. Enzyme-multiplied immunoassay technique (EMIT)
C. Gas chromatography with mass spectroscopy (GC-MS)
D. TLC

C. Gas chromatography with mass spectroscopy (GC-MS)

How well did you know this?

Not at all

Perfectly

The fragments typically produced and analyzed in methods employing mass spectroscopy are typically:

A. Of low molecular size ranging from 10-100 daltons
B. Cations caused by electron loss or proton attachment
C. Anions caused by bombarding the molecule with an electron source
D. Neutral species formed after excited molecules form a stable resonance structure

B. Cations caused by electron loss or proton attachment

How well did you know this?

Not at all

Perfectly

What component is used in a GC-MS but not used in an LC-MS?

A. Electron source
B. Mass filter
C. Detector
D. Vacuum

A. Electron source

How well did you know this?

Not at all

Perfectly

What process is most often used in LC-MS to introduce the sample into the mass filter?

A. Electrospray ionization
B. Chemical ionization
C. Electron impact ionization
D. Fast atom bombardment

A. Electrospray ionization

How well did you know this?

Not at all

Perfectly

In mass spectroscopy, the term base peak typically refers to:

A. The peak with the lowest mass
B. The peak with the most abundance
C. A natural isotope of the molecular ion
D. The first peak to reach the mass detector

B. The peak with the most abundance

How well did you know this?

Not at all

Perfectly

Which method is the most useful when screening for errors of amino and organic acid metabolism?

A. Two-dimensional thin-layer chromatography
B. Gas chromatography
C. Electrospray ionization tandem-mass spectroscopy
D. Inductively charged coupled-mass spectroscopy

C. Electrospray ionization tandem-mass spectroscopy

How well did you know this?

Not at all

Perfectly

In tandem-mass spectroscopy, the first mass filter performs the same function as:

A. The ion source
B. The chromatography column
C. Extraction
D. The vacuum system

B. The chromatography column

How well did you know this?

Not at all

Perfectly

SITUATION: A GC-MS analysis using nitrogen as the carrier gas shows an extensively noisy baseline. A sample of the solvent used for the extraction procedure, ethyl acetate, was injected and showed the same noise. Results of an Autotune test showed the appearance of a base peak at 16 with two smaller peaks at 17 and 18. Tese results indicate:

A. The solvent is contaminated
B. The carrier gas is contaminated
C. There is electrical noise in the detector
D. The ion source is dirty

B. The carrier gas is contaminated

How well did you know this?

Not at all

Perfectly

Why is vacuum necessary in the mass filter of a mass spectrometer?

A. Ionization does not occur at atmospheric pressure
B. It prevents collision between fragments
C. It removes electrons from the ion source
D. It prevents contamination

B. It prevents collision between fragments

How well did you know this?

Not at all

Perfectly

What method is used to introduce the sample into a mass spectrometer for analysis of a trace element?

A. Electrospray ionization
B. Laser desorption
C. Inductively charged plasma (ICP) ionization
D. Direct injection

C. Inductively charged plasma (ICP) ionization

How well did you know this?

Not at all

Perfectly

Which component is needed for a thermal cycler to amplify DNA?

A. Programmable heating and cooling unit
B. Vacuum chamber with zero head space
C. Sealed airtight constant-temperature chamber
D. Temperature-controlled ionization chamber

A. Programmable heating and cooling unit

How well did you know this?

Not at all

Perfectly

In real-time PCR, what value is needed in order to determine the threshold?

A. Background signal
B. Melt temperature
C. Maximum fluorescence
D. Treshold cycle

A. Background signal

How well did you know this?

Not at all

Perfectly

Given the following real-time PCR amplification curve, what is the threshold cycle?

A. 15
B. 20
C. 25
D. 30

C. 25

How well did you know this?

Not at all

Perfectly

In addition to velocity, what variable is also needed to calculate the relative centrifugal force (g force) of a centrifuge?

A. Head radius
B. Angular velocity coefficient
C. Diameter of the centrifuge tube
D. Ambient temperature in degrees Centigrade

A. Head radius

How well did you know this?

Not at all

Perfectly

Which of the following situations is likely to cause an error when weighing with an electronic
analytical balance?

A. Failure to keep the knife edge clean
B. Failure to close the doors of the balance before reading the weight
C. Oxidation on the surface of the substitution weights
D. Using the balance without allowing it to warm up for at least 10 minutes

B. Failure to close the doors of the balance before reading the weight

How well did you know this?

Not at all

Perfectly

When calibrating a semiautomatic pipet that has a fixed delivery of 10.0 µL using a gravimetric method, what should be the average weight of deionized water transferred?

A. 10.0 µg
B. 100.0 µg
C. 1.0 mg
D. 10.0 mg

D. 10.0 mg

How well did you know this?

Not at all

Perfectly

Which of the following represents the Henderson Hasselbalch equation as applied to blood pH?

A. pH = 6.1 + log HCO3-/PCO2
B. pH = 6.1 + log HCO3-/ (0.03 × PCO2)
C. pH = 6.1 + log dCO2/HCO3-
D.pH=6.1 + log (0.03×PCO2) / HCO3-

B. pH = 6.1 + log HCO3-/ (0.03 × PCO2)

How well did you know this?

Not at all

Perfectly

What is the PO2 of calibration gas containing 20.0% O2, when the barometric pressure is 30 in.?

A. 60 mm Hg
B. 86 mm Hg
C. 143 mm Hg
D. 152 mm Hg

C. 143 mm Hg

How well did you know this?

Not at all

Perfectly

What is the blood pH when the partial pressure of carbon dioxide (PCO2) is 60 mm Hg and the bicarbonate concentration is 18 mmol/L?

A. 6.89
B. 7.00
C. 7.10
D. 7.30

C. 7.10

How well did you know this?

Not at all

Perfectly

Which of the following best represents the reference (normal) range for arterial pH?

A. 7.35-7.45
B. 7.42-7.52
C. 7.38-7.68
D. 6.85-7.56

A. 7.35-7.45

How well did you know this?

Not at all

Perfectly

What is the normal ratio of bicarbonate to dissolved carbon dioxide (HCO3 - :dCO2) in
arterial blood?

A. 1:10
B. 10:1
C. 20:1
D. 30:1

C. 20:1

How well did you know this?

Not at all

Perfectly

What is the PCO2 if the dCO2 is 1.8 mmol/L?

A. 24 mm Hg
B. 35 mm Hg
C. 60 mm Hg
D. 72 mm Hg

C. 60 mm Hg

How well did you know this?

Not at all

Perfectly

In the Henderson-Hasselbalch expression pH = 6.1 + log HCO3
- /dCO2, the 6.1 represents:

A. The combined hydration and dissociation constants for CO2 in blood at 37°C
B. The solubility constant for CO2 gas
C. The dissociation constant of H2O
D. The ionization constant of sodium bicarbonate (NaHCO3)

A. The combined hydration and dissociation constants for CO2 in blood at 37°C

How well did you know this?

Not at all

Perfectly

Which of the following contributes the most to the serum total CO2?

A. PCO2
B. dCO2
C. HCO3-
D. Carbonium ion

C. HCO3-

How well did you know this?

Not at all

Perfectly

In addition to sodium bicarbonate, what other substance contributes most to the amount of base in the blood?

A. Hemoglobin concentration
B. Dissolved O2 concentration
C. Inorganic phosphorus
D. Organic phosphate

A. Hemoglobin concentration

How well did you know this?

Not at all

Perfectly

Which of the following effects results from exposure of a normal arterial blood sample to room air?

A. PO2 increased PCO2 decreased pH increased
B. PO2 decreased PCO2 increased pH decreased
C. PO2 increased PCO2 decreased pH decreased
D. PO2 decreased PCO2 decreased pH decreased

A. PO2 increased PCO2 decreased pH increased

How well did you know this?

Not at all

Perfectly

Which of the following formulas for O2 content is correct?

A. O2 content = %O2 saturation/100 × Hgb g/dL × 1.39 mL/g + (0.0031 × PO2)
B. O2 content = PO2 × 0.0306 mmol/L/mm
C. O2 content = O2 saturation × Hgb g/dL × 0.003 mL/g
D. O2 content = O2 capacity × 0.003 mL/g

A. O2 content = %O2 saturation/100 × Hgb g/dL × 1.39 mL/g + (0.0031 × PO2)

How well did you know this?

Not at all

Perfectly

The normal difference between alveolar and arterial PO2 (PAO2-PaO2 difference) is:

A. 3 mm Hg
B. 10 mm Hg
C. 40 mm Hg
D. 50 mm Hg

B. 10 mm Hg

How well did you know this?

Not at all

Perfectly

A decreased PAO2-PaO2 difference is found in:

A. A/V (arteriovenous) shunting
B. V/Q (ventilation/perfusion) inequality
C. Ventilation defects
D. All of these options

C. Ventilation defects

How well did you know this?

Not at all

Perfectly

The determination of the oxygen saturation of hemoglobin is best accomplished by:

A. Polychromatic absorbance measurements of a whole-blood hemolysate
B. Near infrared transcutaneous absorbance measurement
C. Treatment of whole blood with alkaline dithionite prior to measuring absorbance
D. Calculation using PO2 and total hemoglobin by direct spectrophotometry

A. Polychromatic absorbance measurements of a whole-blood hemolysate

How well did you know this?

Not at all

Perfectly

Correction of pH for a patient with a body temperature of 38°C would require:

A. Subtraction of 0.015
B. Subtraction of 0.01%
C. Addition of 0.020
D. Subtraction of 0.020

A. Subtraction of 0.015

How well did you know this?

Not at all

Perfectly

Select the anticoagulant of choice for blood gas studies.

A. Sodium citrate 3.2%
B. Lithium heparin 100 U/mL blood
C. Sodium citrate 3.8%
D. Ammonium oxalate 5.0%

B. Lithium heparin 100 U/mL blood

How well did you know this?

Not at all

Perfectly

What is the maximum recommended storage time and temperature for an arterial blood gas sample drawn in a plastic syringe?

Storage Time / Temperature
A. 10 min 2°C-8°C
B. 20 min 2°C-8°C
C. 30 min 2°C-8°C
D. 30 min 22°C

D. 30 min 22°C

How well did you know this?

Not at all

Perfectly

A patient’s blood gas results are as follows:
pH = 7.26
dCO2 = 2.0 mmol/L
HCO3 - = 29 mmol/L
These results would be classified as:

A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis

C. Respiratory acidosis

How well did you know this?

Not at all

Perfectly

A patient’s blood gas results are:
pH = 7.50
PCO2 = 55 mm Hg
HCO3 - = 40 mmol/L
These results indicate:

A. Respiratory acidosis
B. Metabolic alkalosis
C. Respiratory alkalosis
D. Metabolic acidosis

B. Metabolic alkalosis

How well did you know this?

Not at all

Perfectly

Which set of results is consistent with uncompensated respiratory alkalosis?

A. pH 7.70 HCO3 30 mmol/L PCO2 25 mm Hg
B. pH 7.66 HCO3 22 mmol/L PCO2 20 mm Hg
C. pH 7.46 HCO3 38 mmol/L PCO2 55 mm Hg
D. pH 7.36 HCO3 22 mmol/L PCO2 38 mm Hg

B. pH 7.66 HCO3 22 mmol/L PCO2 20 mm Hg

How well did you know this?

Not at all

Perfectly

Which of the following will shift the O2 dissociation curve to the left?

A. Anemia
B. Hyperthermia
C. Hypercapnia
D. Alkalosis

D. Alkalosis

How well did you know this?

Not at all

Perfectly

In which circumstance will the reporting of calculated oxygen saturation of hemoglobin based on PO2, PCO2, pH, temperature, and hemoglobin be in error?

A. Carbon monoxide poisoning
B. Diabetic ketoacidosis
C. Patient receiving oxygen therapy
D. Assisted ventilation for respiratory failure

A. Carbon monoxide poisoning

How well did you know this?

Not at all

Perfectly

Which would be consistent with partially compensated respiratory acidosis?

A. pH PCO2 Bicarbonate
increased increased increased
B. pH PCO2 Bicarbonate
increased decreased decreased
C. pH PCO2 Bicarbonate
decreased decreased decreased
D. pH PCO2 Bicarbonate
decreased increased increased

D. pH PCO2 Bicarbonate
decreased increased increased

How well did you know this?

Not at all

Perfectly

Which condition results in metabolic acidosis with severe hypokalemia and chronic alkaline urine?

A. Diabetic ketoacidosis
B. Phenformin-induced acidosis
C. Renal tubular acidosis
D. Acidosis caused by starvation

C. Renal tubular acidosis

How well did you know this?

Not at all

Perfectly

Which of the following mechanisms is responsible for metabolic acidosis?

A. Bicarbonate deficiency
B. Excessive retention of dissolved CO2
C. Accumulation of volatile acids
D. Hyperaldosteronism

A. Bicarbonate deficiency

How well did you know this?

Not at all

Perfectly

Which of the following disorders is associated with lactate acidosis?

A. Diarrhea
B. Renal tubular acidosis
C. Hypoaldosteronism
D. Alcoholism

D. Alcoholism

How well did you know this?

Not at all

Perfectly

Which of the following is the primary mechanism of compensation for metabolic acidosis?

A. Hyperventilation
B. Release of epinephrine
C. Aldosterone release
D. Bicarbonate excretion

A. Hyperventilation

How well did you know this?

Not at all

Perfectly

The following conditions are all causes of alkalosis. Which condition is associated with respiratory (rather than metabolic) alkalosis?

A. Anxiety
B. Hypovolemia
C. Hyperaldosteronism
D. Hypoparathyroidism

A. Anxiety

How well did you know this?

Not at all

Perfectly

Which of the following conditions is associated with both metabolic and respiratory alkalosis?

A. Hyperchloremia
B. Hypernatremia
C. Hyperphosphatemia
D. Hypokalemia

D. Hypokalemia

How well did you know this?

Not at all

Perfectly

In uncompensated metabolic acidosis, which of the following will be normal?

A. Plasma bicarbonate
B. PCO2
C. p50
D. Total CO2

B. PCO2

How well did you know this?

Not at all

Perfectly

Which of the following conditions is classified as normochloremic acidosis?

A. Diabetic ketoacidosis
B. Chronic pulmonary obstruction
C. Uremic acidosis
D. Diarrhea

A. Diabetic ketoacidosis

How well did you know this?

Not at all

Perfectly

Which PCO2 value would be seen in maximally compensated metabolic acidosis?

A. 15 mm Hg
B. 30 mm Hg
C. 40 mm Hg
D. 60 mm Hg

A. 15 mm Hg

How well did you know this?

Not at all

Perfectly

A patient has the following arterial blood gas results:
pH = 7.56
PCO2 = 25 mm Hg
PO2 = 100 mm Hg
HCO3 - = 22 mmol/L
These results are most likely the result of which condition?

A. Improper specimen collection
B. Prolonged storage
C. Hyperventilation
D. Hypokalemia

C. Hyperventilation

How well did you know this?

Not at all

Perfectly

Why are three levels used for quality control of pH and blood gases?

A. Systematic errors can be detected earlier than with two controls
B. Analytical accuracy needs to be greater than for other analytes
C. High, normal, and low ranges must always be evaluated
D. A different level is needed for pH, PCO2, and PO2

A. Systematic errors can be detected earlier than with two controls

How well did you know this?

Not at all

Perfectly

A single-point calibration is performed between each blood gas sample in order to:

A. Correct the electrode slope
B. Correct electrode and instrument drift
C. Compensate for temperature variance
D. Prevent contamination by the previous sample

B. Correct electrode and instrument drift

How well did you know this?

Not at all

Perfectly

In which condition would hypochloremia be expected?

A. Respiratory alkalosis
B. Metabolic acidosis
C. Metabolic alkalosis
D. All of these options

C. Metabolic alkalosis

How well did you know this?

Not at all

Perfectly

Given the following serum electrolyte data, determine the anion gap.
Na = 132 mmol/L
Cl = 90 mmol/L
HCO3- = 22 mmol/L

A. 12 mmol/L
B. 20 mmol/L
C. 64 mmol/L
D. Cannot be determined from the information provided

B. 20 mmol/L

How well did you know this?

Not at all

Perfectly

Which of the following conditions will cause an increased anion gap?

A. Diarrhea
B. Hypoaldosteronism
C. Hyperkalemia
D. Renal failure

D. Renal failure

How well did you know this?

Not at all

Perfectly

Alcoholism, liver failure, and hypoxia induce acidosis by causing:

A. Depletion of cellular NAD+
B. Increased excretion of bicarbonate
C. Increased retention of PCO2
D. Loss of carbonic anhydrase

A. Depletion of cellular NAD+

How well did you know this?

Not at all

Perfectly

Which of the following is the primary mechanism causing respiratory alkalosis?

A. Hyperventilation
B. Deficient alveolar diffusion
C. Deficient pulmonary perfusion
D. Parasympathetic inhibition

A. Hyperventilation

How well did you know this?

Not at all

Perfectly

Which condition can result in acidosis?

A. Cystic fibrosis
B. Vomiting
C. Hyperaldosteronism
D. Excessive O2 therapy

D. Excessive O2 therapy

How well did you know this?

Not at all

Perfectly

Which of the following conditions is associated with an increase in ionized calcium (Cai) in the blood?

A. Alkalosis
B. Hypoparathyroidism
C. Hyperalbuminemia
D. Malignancy

D. Malignancy

How well did you know this?

Not at all

Perfectly

Which of the following laboratory results is consistent with primary hypoparathyroidism?

A. Low calcium; high inorganic phosphorus Pi
B. Low calcium; low Pi
C. High calcium; high Pi
D. High calcium; low Pi

A. Low calcium; high inorganic phosphorus Pi

How well did you know this?

Not at all

Perfectly

Which of the following conditions is associated with hypophosphatemia?

A. Rickets
B. Multiple myeloma
C. Renal failure
D. Hypervitaminosis D

A. Rickets

How well did you know this?

Not at all

Perfectly

Which of the following tests is consistently abnormal in osteoporosis?

A. High urinary calcium
B. High serum Pi
C. Low serum calcium
D. High urine or serum N-telopeptide of type 1 collagen

D. High urine or serum N-telopeptide of type 1 collagen

Which of the following is a marker for bone formation?

A. Osteocalcin
B. Tartrate resistant acid phosphatase (TRAP)
C. Urinary pyridinoline and deoxypyridinoline
D. Urinary C-telopeptide and N-telopeptide crosslinks (CTx and NTx

A. Osteocalcin

What role do CTx and NTx play in the management of osteoporosis?

A. Increased urinary excretion is diagnostic of early stage disease
B. Increased levels indicate a low risk of developing osteoporosis
C. Decreased urinary excretion indicates a positive response to treatment
D. The rate of urinary excretion correlates with the stage of the disease

C. Decreased urinary excretion indicates a positive response to treatment

What role does vitamin D measurement play in the management of osteoporosis?

A. Vitamin D deficiency must be demonstrated to establish the diagnosis
B. Vitamin D is consistently elevated in osteoporosis
C. A normal vitamin D level rules out osteoporosis
D. Vitamin D deficiency is a risk factor for developing osteoporosis

D. Vitamin D deficiency is a risk factor for developing osteoporosis

Which statement best describes testing recommendations for vitamin D?

A. Vitamin D testing should be reserved only for those persons who demonstrate hypercalcemia of an undetermined cause
B. Vitamin D testing should be specific for the 1,25(OH)D3 form
C. Testing should be for total vitamin D when screening for deficiency
D. Vitamin D testing should not be performed if the patient is receiving a vitamin D supplement

C. Testing should be for total vitamin D when screening for deficiency

The serum level of which of the following laboratory tests is decreased in both VDDR and VDRR?

A. Vitamin D
B. Calcium
C. Pi
D. Parathyroid hormone

C. Pi

Which of the following is the most accurate measurement of Pi in serum?

A. Rate of unreduced phosphomolybdate formation at 340 nm
B. Measurement of phosphomolybdenum blue at 680 nm
C. Use of aminonaptholsulfonic acid to reduce phosphomolybdate
D. Formation of a complex with malachite green dye

A. Rate of unreduced phosphomolybdate formation at 340 nm

What is the percentage of serum calcium that is ionized (Cai)?

A. 30%
B. 45%
C. 60%
D. 80%

B. 45%

Which of the following conditions is associated with a low serum magnesium?

A. Addison’s disease
B. Hemolytic anemia
C. Hyperparathyroidism
D. Pancreatitis

D. Pancreatitis

Which of the following conditions will cause erroneous Cai results? Assume that the samples are collected and stored anaerobically, kept at 4°C until measurement, and stored for no longer than 1 hour.

A. Slight hemolysis during venipuncture
B. Assay of whole blood collected in sodium oxalate
C. Analysis of serum in a barrier gel tube stored at
4°C until the clot has formed
D. Analysis of whole blood collected in sodium heparin, 20 U/mL (low-heparin tube)

B. Assay of whole blood collected in sodium oxalate

When measuring calcium with the complexometric dye o-cresolphthalein complexone, magnesium is kept from interfering by:

A. Using an alkaline pH
B. Adding 8-hydroxyquinoline
C. Measuring at 450 nm
D. Complexing to EDTA

B. Adding 8-hydroxyquinoline

Which electrolyte measurement is least affected by hemolysis?

A. Potassium
B. Calcium
C. Pi
D. Magnesium

B. Calcium

Which of the following conditions is associated with hypokalemia?

A. Addison’s disease
B. Hemolytic anemia
C. Digoxin intoxication
D. Alkalosis

D. Alkalosis

Which of the following conditions is most likely to produce an elevated plasma potassium?

A. Hypoparathyroidism
B. Cushing’s syndrome
C. Diarrhea
D. Digitalis overdose

D. Digitalis overdose

Which of the following values is the threshold critical value (alert or action level) for low plasma potassium?

A. 1.5 mmol/L
B. 2.0 mmol/L
C. 2.5 mmol/L
D. 3.5 mmol/L

C. 2.5 mmol/L

Which electrolyte is least likely to be elevated in renal failure?

A. Potassium
B. Magnesium
C. Inorganic phosphorus
D. Sodium

D. Sodium

Which of the following is the primary mechanism for vasopressin (ADH) release?

A. Hypovolemia
B. Hyperosmolar plasma
C. Renin release
D. Reduced renal blood flow

B. Hyperosmolar plasma

Which of the following conditions is associated with hypernatremia?

A. Diabetes insipidus
B. Hypoaldosteronism
C. Burns
D. Diarrhea

A. Diabetes insipidus

Which of the following conditions involving
electrolytes is described correctly?

A. Pseudohyponatremia occurs only when
undiluted samples are measured
B. Potassium levels are slightly higher in
heparinized plasma than in serum
C. Hypoalbuminemia causes low total calcium but does not affect Cai
D. Hypercalcemia may be induced by low serum magnesium

C. Hypoalbuminemia causes low total calcium but does not affect Cai

Which of the following values is the threshold critical value (alert or action level) for high plasma sodium?

A. 150 mmol/L
B. 160 mmol/L
C. 170 mmol/L
D. 180 mmol/L

B. 160 mmol/L

Which of the following conditions is associated with hyponatremia?

A. Diuretic therapy
B. Cushing’s syndrome
C. Diabetes insipidus
D. Nephrotic syndrome

A. Diuretic therapy

Which of the following conditions is associated with total body sodium excess?

A. Renal failure
B. Hyperthyroidism
C. Hypoparathyroidism
D. Diabetic ketoacidosis

A. Renal failure

When performing a sweat chloride collection, which of the following steps will result in analytical error?

A. Using unweighed gauze soaked in pilocarpine nitrate on the inner surface of the forearm to stimulate sweating
B. Collecting more than 75 mg of sweat in 30 minutes
C. Leaving the preweighed gauze on the inside of the arm exposed to air during collection
D. Rinsing the collected sweat from the gauze pad using chloride titrating solution

C. Leaving the preweighed gauze on the inside of the arm exposed to air during collection

Which of the following laboratory results is usually associated with cystic fibrosis?

A. Sweat chloride greater than 60 mmol/L
B. Elevated serum sodium and chloride
C. Elevated fecal trypsin activity
D. Low glucose

A. Sweat chloride greater than 60 mmol/L

Which electrolyte level best correlates with plasma osmolality?

A. Sodium
B. Chloride
C. Bicarbonate
D. Calcium

A. Sodium

Which formula is most accurate in predicting plasma osmolality?

A. Na + 2(Cl) + BUN + glucose
B. 2(Na) + 2(Cl) + glucose + urea
C. 2(Na) + (glucose ÷ 18) + (BUN ÷ 2.8)
D. Na + Cl + K + HCO3

C. 2(Na) + (glucose ÷ 18) + (BUN ÷ 2.8)

Which of the following biochemical processes is promoted by insulin?

A. Glycogenolysis
B. Gluconeogenesis
C. Lipolysis
D. Uptake of glucose by cells

D. Uptake of glucose by cells

Which of the following hormones promotes hyperglycemia?

A. Calcitonin
B. Growth hormone
C. Aldosterone
D. Renin

B. Growth hormone

Which of the following is characteristic of type 1 diabetes mellitus?

A. Requires an oral glucose tolerance test for diagnosis
B. Is the most common form of diabetes mellitus
C. Usually occurs after age 40
D. Requires insulin replacement to prevent ketosis

D. Requires insulin replacement to prevent ketosis

Which of the following is characteristic of type 2 diabetes mellitus?

A. Insulin levels are consistently low
B. Most cases require a 3-hour oral glucose tolerance test to diagnose
C. Hyperglycemia is often controlled without insulin replacement
D. The condition is associated with unexplained weight loss

C. Hyperglycemia is often controlled without insulin replacement

Which of the following results falls within the diagnostic criteria for diabetes mellitus?

A. Fasting plasma glucose of 120 mg/dL
B. Two-hour postprandial plasma glucose of 160 mg/dL
C. Two-hour plasma glucose of 180 mg/dL following a 75 g oral glucose challenge
D. Random plasma glucose of 250 mg/dL and presence of symptoms

D. Random plasma glucose of 250 mg/dL and presence of symptoms

Select the most appropriate adult reference range for fasting blood glucose.

A. 40-105 mg/dL (2.22-5.82 mmol/L)
B. 60-140 mg/dL (3.33-7.77 mmol/L)
C. 65-99 mg/dL (3.61-5.50 mmol/L)
D. 75-150 mg/dL (4.16-8.32 mmol/L)

C. 65-99 mg/dL (3.61-5.50 mmol/L)

When preparing a patient for an oral glucose tolerance test (OGTT), which of the following conditions will lead to erroneous results?

A. The patient remains ambulatory for 3 days prior to the test
B. Carbohydrate intake is restricted to below 150 g/day for 3 days prior to test
C. No food, coffee, tea, or smoking is allowed 8 hours before and during the test
D. Administration of 75 g of glucose is given to an adult patient following a 10-12-hour fast

B. Carbohydrate intake is restricted to below 150 g/day for 3 days prior to test

Which of the following 2-hour glucose challenge results would be classified as impaired glucose tolerance (IGT)?
Two-hour serum glucose:

A. 130 mg/dL
B. 135 mg/dL
C. 150 mg/dL
D. 204 mg/dL

C. 150 mg/dL

Which statement regarding gestational diabetes mellitus (GDM) is correct?

A. Is diagnosed using the same oral glucose tolerance criteria as in nonpregnancy
B. Converts to diabetes mellitus after pregnancy in 60%-75% of cases
C. Presents no increased health risk to the fetus
D. Is defined as glucose intolerance originating during pregnancy

D. Is defined as glucose intolerance originating during pregnancy

Which of the following findings is characteristic of all forms of clinical hypoglycemia?

A. A fasting blood glucose value below 55 mg/dL
B. High fasting insulin levels
C. Neuroglycopenic symptoms at the time of low blood sugar
D. Decreased serum C peptide

C. Neuroglycopenic symptoms at the time of low blood sugar

Which statement regarding glycated (glycosylated) Hgb (G-Hgb) is true?

A. Has a sugar attached to the C-terminal end of the β chain
B. Is a highly reversible aminoglycan
C. Reflects the extent of glucose regulation in the 8- to 12-week interval prior to sampling
D. Will be abnormal within 4 days following an episode of hyperglycemia

C. Reflects the extent of glucose regulation in the 8- to 12-week interval prior to sampling

What is the American Diabetes Association recommended cutoff value for adequate control of blood glucose in diabetics as measured by glycated hemoglobin?

A. 5%
B. 6.5%
C. 9.5%
D. 11%

B. 6.5%

Which statement regarding measurement of Hgb A1c is true?

A. Levels do not need to be done fasting
B. Both the labile and stable Hgb A1c fractions are measured
C. Samples should be measured within 2 hours of collection
D. The assay must be done by chromatography

A. Levels do not need to be done fasting

Which stationary phase is used for the measurement of hemoglobin A1c by high performance liquid chromatography?

A. Octadecylsilane (C18)
B. Cation exchanger
C. Anion exchanger
D. Polystyrene divinylbenzene

B. Cation exchanger

Evaluate the following chromatogram of a whole-blood hemolysate, and identify the cause and best course of action.

A. Result is not reportable because hemoglobin F is present and interferes
B. The result is not reportable because hemoglobin C is present and interferes
C. The result is not reportable because labile hemoglobin A1c is present
D. The result is reportable; neither hemoglobin F or C interfere

D. The result is reportable; neither hemoglobin F or C interfere

Which statement best describes the use of the Hgb A1C test?

Peak / Calibrated % Area / % Area / Retention Time / Peak Area

Alb / 0.60/ 0.25/ 12500
F/ 0.50/ 0.50/ 11300
LA1c/ 0.75/ 0.70/ 15545
A1c/ 6.2/ 0.90/ 45112
P3/ 2.6 /1.60 /57489
Ao /48.0/ 1.8/ 994813
C/ 43.0 /2.00/ 926745

A. Should be used for monitoring glucose control only
B. May be used for both diagnosis and monitoring
C. Should be used only to monitor persons with type 1 diabetes
D. May be used only to monitor persons with type 2 diabetes

B. May be used for both diagnosis and monitoring

According to American Diabetes Association criteria, which result is consistent with a diagnosis of impaired fasting glucose?

A. 99 mg/dL
B. 117 mg/dL
C. 126 mg/dL
D. 135 mg/dL

B. 117 mg/dL

In addition to measuring blood glucose, Hgb A1c, and microalbumin, which test should be done on diabetic persons once per year?

A. Urine glucose
B. Urine ketones
C. Plasma fructosamines
D. Estimated glomerular filtration rate

D. Estimated glomerular filtration rate

What is the recommended cutoff for the early detection of chronic kidney disease in diabetics using the test for microalbuminuria?

A. >30 mg/g creatinine
B. >80 mg/g creatinine
C. >200 mg/g creatinine
D. >80 mg/L

A. >30 mg/g creatinine

Which testing situation is appropriate for the use of point-of-care whole-blood glucose methods?

A. Screening for type 2 diabetes mellitus
B. Diagnosis of diabetes mellitus
C. Monitoring of blood glucose control in type 1 and type 2 diabetics
D. Monitoring diabetics for hyperglycemic episodes only

C. Monitoring of blood glucose control in type 1 and type 2 diabetics

Which of the following is the reference method for measuring serum glucose?

A. Somogyi-Nelson
B. Hexokinase
C. Glucose oxidase
D. Glucose dehydrogenase

B. Hexokinase

Polarographic methods for glucose analysis are based upon which principle of measurement?

A. Nonenzymatic oxidation of glucose
B. The rate of O2 depletion
C. Chemiluminescence caused by formation of adenosine triphosphate (ATP)
D. The change in electrical potential as glucose is oxidized

B. The rate of O2 depletion

In addition to polarography, what other electrochemical method can be used to measure glucose in plasma?

A. Conductivity
B. Potentiometry
C. Anodic stripping voltammetry
D. Amperometry

D. Amperometry

Select the coupling enzyme used in the hexokinase method for glucose.

A. Glucose-6-phosphate dehydrogenase
B. Peroxidase
C. Glucose dehydrogenase
D. Glucose-6-phosphatase

A. Glucose-6-phosphate dehydrogenase

Which glucose method is subject to falsely low results caused by ascorbate?

A. Hexokinase
B. Glucose dehydrogenase
C. Trinder glucose oxidase
D. Polarography

C. Trinder glucose oxidase

Select the enzyme that is most specific for β-D-glucose.

A. Hexokinase
B. G-6-PD
C. Phosphohexisomerase
D. Glucose oxidase

D. Glucose oxidase

Which of the following is a potential source of error in the hexokinase method?

A. Galactosemia
B. Hemolysis
C. Sample collected in fluoride
D. Ascorbic acid

B. Hemolysis

Which statement about glucose in cerebrospinal fluid (CSF) is correct?

A. Levels below 40 mg/dL occur in septic meningitis, cancer, and multiple sclerosis
B. CSF glucose is normally the same as the plasma glucose level
C. Hyperglycorrhachia is caused by dehydration
D. In some clinical conditions, the CSF glucose can be greater than the plasma glucose

A. Levels below 40 mg/dL occur in septic meningitis, cancer, and multiple sclerosis

In peroxidase-coupled glucose methods, which reagent complexes with the chromogen?

A. Nitroprusside
B. Phenol
C. Tartrate
D. Hydroxide

B. Phenol

Point-of-care-tests (POCTs) for whole-blood glucose monitoring are based mainly on the use of:

A. Glucose oxidase as the enzyme
B. Amperometric detection
C. Immunochromatography
D. Peroxidase coupling reactions

B. Amperometric detection

What effect does hematocrit have on POCT tests for whole-blood glucose monitoring?

A. Low hematocrit decreases glucose readings on all devices
B. High hematocrit raises glucose readings on all devices
C. The effect is variable and dependent on the enzyme/coenzyme system
D. Low hematocrit raises readings and high hematocrit lowers readings unless corrected

D. Low hematocrit raises readings and high hematocrit lowers readings unless corrected

Which of the following is classified as a mucopolysaccharide storage disease?

A. Pompe’s disease
B. von Gierke disease
C. Hers’ disease
D. Hurler’s syndrome

D. Hurler’s syndrome

Identify the enzyme deficiency responsible for type 1 glycogen storage disease (von Gierke’s disease).

A. Glucose-6-phosphatase
B. Glycogen phosphorylase
C. Glycogen synthetase
D. β-Glucosidase

A. Glucose-6-phosphatase

Which of the following abnormal laboratory results is found in von Gierke’s disease?

A. Hyperglycemia
B. Increased glucose response to epinephrine administration
C. Metabolic alkalosis
D. Hyperlipidemia

D. Hyperlipidemia

The D-xylose absorption test is used for the differential diagnosis of which two diseases?

A. Pancreatic insufficiency from malabsorption
B. Primary from secondary disorders of glycogen synthesis
C. Type 1 and type 2 diabetes mellitus
D. Generalized from specific carbohydrate intolerance

A. Pancreatic insufficiency from malabsorption

Which of the following statements about carbohydrate intolerance is true?

A. Galactosemia results from deficiency of galactose-1-phosphate (galactose-1-PO4) uridine diphosphate transferase
B. Galactosemia results in a positive glucose oxidase test for glucose in urine
C. Urinary galactose is seen in both galactosemia and lactase deficiency
D. A galactose tolerance test is used to confirm a diagnosis of galactosemia

A. Galactosemia results from deficiency of galactose-1-phosphate (galactose-1-PO4) uridine diphosphate transferase

Which of the following statements regarding iron metabolism is correct?

A. Iron absorption is decreased by alcohol ingestion
B. Normally, 40%-50% of ingested iron is absorbed
C. The daily requirement is higher for pregnant and menstruating women
D. Absorption increases with the amount of iron in the body stores

C. The daily requirement is higher for pregnant and menstruating women

Which of the following processes occurs when iron is in the oxidized (Fe3+) state?

A. Absorption by intestinal epithelium
B. Binding to transferrin and incorporation into ferritin
C. Incorporation into protoporphyrin IX to form functional heme
D. Reaction with chromogens in colorimetric assays

B. Binding to transferrin and incorporation into ferritin

Which of the following is associated with low serum iron and high total iron-binding capacity (TIBC)?

A. Iron deficiency anemia
B. Hepatitis
C. Nephrosis
D. Noniron deficiency anemias

A. Iron deficiency anemia

Which condition is associated with the lowest percent saturation of transferrin?

A. Hemochromatosis
B. Anemia of chronic infection
C. Iron deficiency anemia
D. Noniron deficiency anemia

C. Iron deficiency anemia

Which condition is most often associated with a high serum iron level?

A. Nephrosis
B. Chronic infection or inflammation
C. Polycythemia vera
D. Noniron deficiency anemias

D. Noniron deficiency anemias

Which formula provides the best estimate of serum TIBC?

A. Serum transferrin in mg/dL × 0.70 = TIBC (µg/dL)
B. Serum transferrin in mg/dL × 1.43 = TIBC (µg/dL)
C. Serum iron (µg/dL)/1.2 + 0.06 = TIBC (µg/dL)
D. Serum Fe (µg/dL) × 1.25 = TIBC (µg/dL)

B. Serum transferrin in mg/dL × 1.43 = TIBC (µg/dL)

Which of the following is likely to occur first in iron deficiency anemia?

A. Decreased serum iron
B. Increased TIBC
C. Decreased serum ferritin
D. Increased transferrin

C. Decreased serum ferritin

Which statement regarding the diagnosis of iron deficiency is correct?

A. Serum iron levels are always higher at night than during the day
B. Serum iron levels begin to fall before the body stores become depleted
C. A normal level of serum ferritin rules out iron deficiency
D. A low serum ferritin is diagnostic of iron deficiency

D. A low serum ferritin is diagnostic of iron deficiency

Which statement about iron methods is true?

A. Interference from Hgb can be corrected by a serum blank
B. Colorimetric methods measure binding of Fe2+ to a ligand such as ferrozine
C. Atomic absorption is the method of choice for measurement of serum iron
D. Serum iron can be measured by potentiometry

B. Colorimetric methods measure binding of Fe2+ to a ligand such as ferrozine

Which of the following statements regarding the metabolism of bilirubin is true?

A. It is formed by hydrolysis of the α methene bridge of urobilinogen
B. It is reduced to biliverdin prior to excretion
C. It is a by-product of porphyrin production
D. It is produced from the destruction of RBCs

D. It is produced from the destruction of RBCs

Which enzyme is responsible for the conjugation of bilirubin?

A. β-Glucuronidase
B. UDP-glucuronyl transferase
C. Bilirubin oxidase
D. Biliverdin reductase

B. UDP-glucuronyl transferase

Bilirubin is transported from reticuloendothelial cells to the liver by:

A. Albumin
B. Bilirubin-binding globulin
C. Haptoglobin
D. Transferrin

A. Albumin

Which of the following statements regarding the TIBC assay is correct?

A. All TIBC methods require addition of excess iron to saturate transferrin
B. All methods require the removal of unbound iron
C. Measurement of TIBC is specific for transferrin-bound iron
D. The chromogen used must be different from the one used for measuring serum iron

A. All TIBC methods require addition of excess iron to saturate transferrin

In the liver, bilirubin is conjugated by addition of:

A. Vinyl groups
B. Methyl groups
C. Hydroxyl groups
D. Glucuronyl groups

D. Glucuronyl groups

The term δ-bilirubin refers to:

A. Water-soluble bilirubin
B. Free unconjugated bilirubin
C. Bilirubin tightly bound to albumin
D. Direct-reacting bilirubin

C. Bilirubin tightly bound to albumin

Which of the following processes is part of the normal metabolism of bilirubin?

A. Both conjugated and unconjugated bilirubin are excreted into the bile
B. Methene bridges of bilirubin are reduced by intestinal bacteria forming urobilinogens
C. Most of the bilirubin delivered into the intestine is reabsorbed
D. Bilirubin and urobilinogen reabsorbed from the intestine are mainly excreted by the kidneys

B. Methene bridges of bilirubin are reduced by intestinal bacteria forming urobilinogens

Which of the following statements regarding urobilinogen is true?

A. It is formed in the intestines by bacterial reduction of bilirubin
B. It consists of a single water-soluble bile pigment
C. It is measured by its reaction with p-aminosalicylate
D. In hemolytic anemia, it is decreased in urine and feces

A. It is formed in the intestines by bacterial reduction of bilirubin

Which of the following is a characteristic of conjugated bilirubin?

A. It is water soluble
B. It reacts more slowly than unconjugated bilirubin
C. It is more stable than unconjugated bilirubin
D. It has the same absorbance properties as unconjugated bilirubin

A. It is water soluble

Which statement regarding bilirubin metabolism is true?

A. Bilirubin undergoes rapid photo-oxidation when exposed to daylight
B. Bilirubin excretion is inhibited by barbiturates
C. Bilirubin excretion is increased by chlorpromazine
D. Bilirubin is excreted only as the diglucuronide

A. Bilirubin undergoes rapid photo-oxidation when exposed to daylight

Which condition is caused by deficient secretion of bilirubin into the bile canaliculi?

A. Gilbert’s disease
B. Neonatal hyperbilirubinemia
C. Dubin-Johnson syndrome
D. Crigler-Najjar syndrome

C. Dubin-Johnson syndrome

In hepatitis, the rise in serum conjugated bilirubin can be caused by:

A. Secondary renal insufficiency
B. Failure of the enterohepatic circulation
C. Enzymatic conversion of urobilinogen to bilirubin
D. Extrahepatic conjugation

B. Failure of the enterohepatic circulation

Which of the following is a characteristic of obstructive jaundice?
A. The ratio of direct to total bilirubin is greater than 1:2
B. Conjugated bilirubin is elevated, but
unconjugated bilirubin is normal
C. Urinary urobilinogen is increased
D. Urinary bilirubin is normal

A. The ratio of direct to total bilirubin is greater than 1:2

Which of the following would cause an increase in only the unconjugated bilirubin?

A. Hemolytic anemia
B. Obstructive jaundice
C. Hepatitis
D. Hepatic cirrhosis

A. Hemolytic anemia

Which form of hyperbilirubinemia is caused by an inherited absence of UDP-glucuronyl transferase?

A. Gilbert’s syndrome
B. Rotor syndrome
C. Crigler-Najjar syndrome
D. Dubin-Johnson syndrome

C. Crigler-Najjar syndrome

Which statement regarding total and direct bilirubin levels is true?

A. Total bilirubin level is a less sensitive and specific marker of liver disease than the direct level
B. Direct bilirubin exceeds 3.5 mg/dL in most cases of hemolytic anemia
C. Direct bilirubin is normal in cholestatic liver disease
D. The ratio of direct to total bilirubin exceeds 0.40 in hemolytic anemia

A. Total bilirubin level is a less sensitive and specific marker of liver disease than the direct level

Which statement best characterizes serum bilirubin levels in the first week following delivery?

A. Serum bilirubin 24 hours after delivery should not exceed the upper reference limit for adults
B. Jaundice is usually first seen 48-72 hours postpartum in neonatal hyperbilirubinemia
C. Serum bilirubin above 5.0 mg/dL occurring 2-5 days after delivery indicates hemolytic or hepatic disease
D. Conjugated bilirubin accounts for about 50% of the total bilirubin in neonates

B. Jaundice is usually first seen 48-72 hours postpartum in neonatal hyperbilirubinemia

Which form of jaundice occurs within days of delivery and usually lasts 1-3 weeks, but is not due to normal neonatal hyperbilirubinemia or hemolytic disease of the newborn?

A. Gilbert syndrome
B. Lucey -Driscoll syndrome
C. Rotor syndrome
D. Dubin-Johnson syndrome

B. Lucey -Driscoll syndrome

A lab measures total bilirubin by the Jendrassik-Grof bilirubin method with sample blanking. What would be the effect of moderate hemolysis on the test result?

A. Falsely increased due to optical interference
B. Falsely increased due to release of bilirubin from RBCs
C. Falsely low due to inhibition of the diazo reaction by hemoglobin
D. No effect due to correction of positive interference by sample blanking

C. Falsely low due to inhibition of the diazo reaction by hemoglobin

Which reagent is used in the Jendrassik-Grof method to solubilize unconjugated bilirubin?

A. 50% methanol
B. N-butanol
C. Caffeine
D. Acetic acid

C. Caffeine

Which statement about colorimetric bilirubin methods is true?

A. Direct bilirubin must react with diazo reagent under alkaline conditions
B. Most methods are based upon reaction with diazotized sulfanilic acid
C. Ascorbic acid can be used to eliminate interference caused by Hgb
D. The color of the azobilirubin product is independent of pH

B. Most methods are based upon reaction with diazotized sulfanilic acid

Which statement regarding the measurement of bilirubin by the Jendrassik-Grof method is
correct?

A. The same diluent is used for both total and direct assays to minimize differences in reactivity
B. Positive interference by Hgb is prevented by the addition of HCl after the diazo reaction
C. The color of the azobilirubin product is intensified by the addition of ascorbic acid
D. Fehling’s reagent is added after the diazo reaction to reduce optical interference by hemoglobin

D. Fehling’s reagent is added after the diazo reaction to reduce optical interference by hemoglobin

A neonatal bilirubin assay performed at the nursery by bichromatic direct spectrophotometry is 4.0 mg/dL. Four hours later, a second sample assayed for total bilirubin by the Jendrassik-Grof method gives a result of 3.0 mg/dL. Both samples are reported to be hemolyzed. What is the most likely explanation of these results?

A. Hgb interference in the second assay
B. δ-Bilirubin contributing to the result of the first assay
C. Falsely high results from the first assay caused by direct bilirubin
D. Physiological variation owing to premature hepatic microsomal enzymes

A. Hgb interference in the second assay

In the enzymatic assay of bilirubin, how is measurement of both total and direct bilirubin
accomplished?

A. Using different pH for total and direct assays
B. Using UDP glucuronyl transferase and bilirubin reductase
C. Using different polarity modifiers
D. Measuring the rate of absorbance decrease at different time intervals

A. Using different pH for total and direct assays

What is the principle of the transcutaneous bilirubin assay?

A. Conductivity
B. Amperometric inhibition
C. Multiwavelength reflectance photometry
D. Infrared spectroscopy

C. Multiwavelength reflectance photometry

How many grams of sodium hydroxide (NaOH) are required to prepare 150.0 mL of a 5.0% w/v solution?

A. 1.5 g
B. 4.0 g
C. 7.5 g
D. 15.0 g

C. 7.5 g

How many milliliters of glacial acetic acid are needed to prepare 2.0 L of 10.0% v/v acetic acid?

A. 10.0 mL
B. 20.0 mL
C. 100.0 mL
D. 200.0 mL

D. 200.0 mL

A biuret reagent requires preparation of a stock solution containing 9.6 g of copper II sulfate (CuSO4) per liter. How many grams of CuSO4 * 5H2O are needed to prepare 1.0 L of the stock solution?
Atomic weights: H = 1.0; Cu = 63.6; O = 16.0; S = 32.1

A. 5.4 g
B. 6.1 g
C. 15.0 g
D. 17.0 g

C. 15.0 g

Convert 10.0 mg/dL calcium (atomic weight = 40.1) to International System of Units (SI).

A. 0.25
B. 0.40
C. 2.5
D. 0.4

C. 2.5

How many milliliters of HNO3 (purity 68.0%, specific gravity 1.42) are needed to prepare 1.0 L
of a 2.0 N solution?
Atomic weights: H = 1.0; N = 14.0; O = 16.0

A. 89.5 mL
B. 126.0 mL
C. 130.5 mL
D. 180.0 mL

C. 130.5 mL

Convert 2.0 mEq/L magnesium (atomic weight = 24.3) to milligrams per deciliter.

A. 0.8 mg/dL
B. 1.2 mg/dL
C. 2.4 mg/dL
D. 4.9 mg/dL

C. 2.4 mg/dL

How many milliliters of a 2,000.0 mg/dL glucose stock solution are needed to prepare 100.0 mL of a 150.0 mg/dL glucose working standard?

A. 1.5 mL
B. 7.5 mL
C. 15.0 mL
D. 25.0 mL

B. 7.5 mL

What is the pH of a solution of HNO3, if the hydrogen ion concentration is 2.5 × 10-2 M?

A. 1.0
B. 1.6
C. 2.5
D. 2.8

B. 1.6

Calculate the pH of a solution of 1.5 × 10-5 M NH4OH.

A. 4.2
B. 7.2
C. 9.2
D. 11.2

C. 9.2

What is the pH of a 0.05 M solution of acetic acid? Ka = 1.75 × 10-5, pKa = 4.76

A. 1.7
B. 3.0
C. 4.3
D. 4.6

B. 3.0

How many significant figures should be reported when the pH of a 0.060 M solution of nitric acid is calculated?

A. 1
B. 2
C. 3
D. 4

B. 2

A solvent needed for HPLC requires a 20.0 mmol/L phosphoric acid buffer, pH 3.50, made by mixing KH2PO4 and H3PO4. How many grams of KH2PO4 are required to make 1.0 L of this buffer?
Formula weights: KH2PO4 = 136.1; H3PO4 = 98.0;
pKa H3PO4 = 2.12

A. 1.96 g
B. 2.61 g
C. 2.72 g
D. 19.2 g

B. 2.61 g

What is the pH of a buffer containing 40.0 mmol/L NaHC2O4 and 4.0 mmol/L H2C2O4? (pKa = 1.25)

A. 1.35
B. 2.25
C. 5.75
D. 6.12

B. 2.25

A procedure for cholesterol is calibrated with a serum-based cholesterol standard that was determined by the Abell-Kendall method to be 200.0 mg/dL. Assuming the same volume of sample and reagent are used, calculate the cholesterol concentration in the patient’s sample from the following results.
Standard Concentration /Absorbance of Reagent Blank / Absorbance of Standard/
Absorbance of Patient Serum
200 mg/dL/ 0.00 /0.860/ 0.740

A. 123 mg/dL
B. 172 mg/dL
C. 232 mg/dL
D. 314 mg/dL

B. 172 mg/dL

A glycerol kinase method for triglyceride calls for a serum blank in which normal saline is substituted for lipase in order to measure endogenous glycerol. Given the following results, and assuming the same volume of sample and reagent are used for each test, calculate the triglyceride concentration in the patient’s sample.

Std Concentration : 125mg/dL
Absorbance of RB: 0.000
Abs of Std: 0.62
Abs of Pt Serum: 0.750
Abs of Serum Blank: 0.100

A. 119 mg/dL
B. 131 mg/dL
C. 156 mg/dL
D. 180 mg/dL

B. 131 mg/dL

A procedure for aspartate aminotransferase (AST) is performed manually because of a repeating error code for nonlinearity obtained on the laboratory’s automated chemistry analyzer; 0.05 mL of serum and 1.0 mL of substrate are used. Te reaction rate is measured at 30°C at 340 nm using a 1.0 cM light path, and the delta absorbance (-∆A) per minute is determined to be 0.382. Based upon a molar absorptivity coefficient for NADH at 340 nm of 6.22 X 103 M-1 cM-1 L-1, calculate the enzyme activity in international units (IUs) per liter.

A. 26 IU/L
B. 326 IU/L
C. 1228 IU/L
D. 1290 IU/L

D. 1290 IU/L

When referring to quality control (QC) results, what parameter usually determines the acceptable range?

A. The 95% confidence interval for the mean
B. The range that includes 50% of the results
C. The central 68% of results
D. The range encompassed by ±2.5 standard deviations

A. The 95% confidence interval for the mean

Which of the following quality control (QC) rules would be broken 1 out of 20 times by chance alone?

A. 12s
B. 22s
C. 13s
D. 14s

A. 12s

Which of the following conditions is cause for rejecting an analytical run?

A. Two consecutive controls greater than 2 s above or below the mean
B. Tree consecutive controls greater than 1 s above the mean
C. Four controls steadily increasing in value but less than ±1 s from the mean
D. One control above +1 s and the other below -1 s from the mean

A. Two consecutive controls greater than 2 s above or below the mean

The term R4S means that:

A. Four consecutive controls are greater than ±1 standard deviation from the mean
B. Two controls in the same run are greater than 4s units apart
C. Two consecutive controls in the same run are each greater than ±4s from the mean
D. There is a shift above the mean for four consecutive controls

B. Two controls in the same run are greater than 4s units apart

Two consecutive controls are both beyond -2s from the mean. How frequently would this occur on the basis of chance alone?

A. 1:100
B. 5:100
C. 1:400
D. 1:1,600

D. 1:1,600

One of two controls within a run is above +2s and the other control is below -2s from the mean. What do these results indicate?

A. Poor precision has led to random error (RE)
B. A systematic error (SE) is present
C. Proportional error is present
D. QC material is contaminated

A. Poor precision has led to random error (RE)

A trend in QC results is most likely caused by:

A. Deterioration of the reagent
B. Miscalibration of the instrument
C. Improper dilution of standards
D. Electronic noise

A. Deterioration of the reagent

In most circumstances, when two controls within a run are both greater than ±2s from the mean, what action should be taken first?

A. Recalibrate, then repeat controls followed by selected patient samples if quality control is acceptable
B. Repeat the controls before taking any corrective action
C. Change the reagent lot, then recalibrate
D. Prepare fresh standards and recalibrate

A. Recalibrate, then repeat controls

When establishing QC limits, which of the following practices is inappropriate?

A. Using last month’s QC data to determine current target limits
B. Exclusion of any QC results greater than ±2s from the mean
C. Using control results from all shifts on which the assay is performed
D. Using limits determined by reference laboratories using the same method

B. Exclusion of any QC results greater than ±2s from the mean

Which of the following plots is best for detecting all types of QC errors?

A. Levy-Jennings
B. Tonks-Youden
C. Cusum
D. Linear regression

A. Levy-Jennings

Given the following data, calculate the coefficient
of variation for glucose.

Analyte / Mean / Std Deviation
Glucose / 76mg/dL / 2.3

A. 3.0%
B. 4.6%
C. 7.6%
D. 33.0%

A. 3.0%

Which of the following assays has the poorest precision?

Analyte / Mean (mmol/L) / Std Deviation

A. Ca / 2.5 / 0.3
B. K / 4.0 / 0/4
C. Na / 140 / 4.0
D. Cl / 100 / 2.5

A. Ca / 2.5 / 0.3

Which of the following plots is best for comparison of precision and accuracy among laboratories?

A. Levy-Jennings
B. Tonks-Youden
C. Cusum
D. Linear regression

B. Tonks-Youden

Which plot will give the earliest indication of a shift or trend?

A. Levy-Jennings
B. Tonks-Youden
C. Cusum
D. Histogram

C. Cusum

Which of the following tumor markers is classified as a tumor suppressor gene?

A. BRCA-1
B. Carcinoembryonic antigen (CEA)
C. Human chorionic gonadotropin (hCG)
D. Nuclear matrix protein

A. BRCA-1

In general, in which of the following situations is the analysis of a tumor marker most useful?

A. Testing for recurrence
B. Prognosis
C. Screening
D. Diagnosis

A. Testing for recurrence

Which of the following enzymes is increased in persons with prostate and small-cell lung cancer?

A. Creatine kinase-1 (CK-1)
B. Gamma glutamyl transferase (GGT)
C. Amylase
D. Lactate dehydrogenase

A. Creatine kinase-1 (CK-1)

Which of the following is the best analyte to monitor for recurrence of ovarian cancer?

A. CA-15-3
B. CA-19-9
C. CA-125
D. CEA

C. CA-125

Which tumor marker is associated with cancer of the urinary bladder?

A. CA-19-9
B. CA-72-4
C. Nuclear matrix protein
D. Cathepsin-D

C. Nuclear matrix protein

A person presents with a cushingoid appearance and an elevated 24-hour urinary cortisol level. The plasma adrenocotropic hormone (ACTH) is very elevated, and the physician suspects the cause is ectopic ACTH production. Which test would be most useful in substantiating this diagnosis?

A. Plasma cortisol
B. CA-50
C. Alkaline phosphatase isoenzymes
D. AFP

C. Alkaline phosphatase isoenzymes

Which of the following tumor markers is used to monitor persons with breast cancer for recurrence of disease?

A. Cathepsin-D
B. CA-15-3
C. Retinoblastoma gene
D. Estrogen receptor (ER)

B. CA-15-3

Which of the following statements regarding the Philadelphia chromosome is true?

A. It is seen exclusively in chronic myelogenous leukemia
B. It results from a translocation
C. It appears as a short-arm deletion of chromosome 21
D. It is associated with a poor prognosis

B. It results from a translocation

What is the primary clinical utility of measuring CEA?

A. Diagnosis of liver cancer
B. Diagnosis of colorectal cancer
C. Screening for cancers of endodermal origin
D. Monitoring for recurrence of cancer

D. Monitoring for recurrence of cancer

A patient treated for a germ cell tumor has a total and free β-hCG assay performed prior to surgery. The result is 40,000 mIU/mL. One week following surgery, the hCG is 5,000 mIU/mL. Chemotherapy is started, and the hCG is measured 1 week later and found to be 10,000 mIU/mL. What does this indicate?

A. Recurrence of the tumor
B. Falsely increased hCG owing to drug interference with the assay
C. Analytical error with the test reported as 5,000 mIU/mL
D. Transient hCG increase caused by chemotherapy

D. Transient hCG increase caused by chemotherapy

Which tumor marker is used to determine the usefulness of trastuzumab (Herceptin) therapy for breast cancer?

A. PR
B. CEA
C. HER-2/neu
D. Myc

C. HER-2/neu

A person is suspected of having testicular cancer. Which type of hCG test would be most useful?

A. Plasma immunoassay for intact hCG only
B. Plasma immunoassay for intact hCG and the β-hCG subunit
C. Plasma immunoassay for the free alpha and β-hCG subunits
D. Urine assay for hCG β core

B. Plasma immunoassay for intact hCG and the β-hCG subunit

Which set of results for ER and PR is associated with the highest likelihood of a favorable response to treatment with estrogen-suppression therapy (tamoxifen)?

A. ER positive, PR positive
B. ER positive, PR negative
C. ER negative, PR positive
D. ER negative, PR negative

A. ER positive, PR positive

Which type of cancer is associated with the highest level of AFP?

A. Hepatoma
B. Ovarian cancer
C. Testicular cancer
D. Breast cancer

A. Hepatoma

Which of the following assays is recommended as a screening test for colorectal cancer in persons over 50 years old?

A. CEA
B. AFP
C. Occult blood
D. Fecal trypsin

C. Occult blood

Which of the following assays is used to determine the risk of developing cancer?

A. Epidermal growth factor receptor (EGF-R)
B. Squamous cell carcinoma antigen (SCC)
C. c-erb B-2 gene expression
D. p53 gene mutation

D. p53 gene mutation

In which of the following conditions is PSA least likely to be increased?

A. Precancerous lesions of the prostate
B. Postprostate biopsy
C. Benign prostatic hypertrophy
D. Post-digital rectal examination

D. Post-digital rectal examination

A person has an elevated 24-hour urinary homovanillic acid (HVA) and vanillymandelic acid (VMA). Urinary metanephrines,
chromogranin A, and neuron specific enolase are also elevated but 5 hydroxyindoleacetic acid is within the reference range. What is the most likely diagnosis?

A. Carcinoid tumors of the intestine
B. Pheochromocytoma
C. Neuroblastoma
D. Pancreatic cancer

C. Neuroblastoma

Which of the following statements regarding PSA is true?

A. Complexed PSA in plasma is normally less than free PSA
B. Free PSA below 25% is associated with malignant disease
C. A total PSA below 4 ng/mL rules out malignant disease
D. A total PSA above 10 ng/mL is diagnostic of malignant disease

B. Free PSA below 25% is associated with malignant disease

Which of the following procedures can be used to detect proportional error in a new method for glucose?

A. Compare the standard deviation of 40 patient samples to the hexokinase method
B. Measure a mixture made from equal parts of normal and high-QC sera
C. Add 5.0 mg of glucose to 1.0 mL of a serum of known concentration and measure
D. Compare the mean of 40 normal samples to the hexokinase method

C. Add 5.0 mg of glucose to 1.0 mL of a serum of known concentration and measure

A 55-year-old male with early stage prostate cancer diagnosed by biopsy had his prostate gland removed (simple prostatectomy). His PSA prior to surgery was 10.0 ng/mL. If the surgery was successful in completely removing the tumor cells, what would the PSA result be 1 month after surgery?

A. Undetectable
B. 1-3 ng/mL
C. Less than 4 ng/mL
D. Less than 10 ng/mL

A. Undetectable

Which of two instruments can be assumed to have the narrower bandpass? Assume that wavelength is accurately calibrated.

A. The instrument giving the highest absorbance for a solution of 0.1 mmol/L NADH at 340 nm
B. The instrument giving the lowest %T for a solution of nickel sulfate at 700 nm
C. The instrument giving the highest %T reading for 1.0% v/v HCl at 350 nm
D. The instrument giving the most linear plot of absorbance versus concentration

A. The instrument giving the highest absorbance for a solution of 0.1 mmol/L NADH at 340 nm

A lipemic sample gives a sodium of 130 mmol/L on an analyzer that uses a 1:50 dilution of serum or plasma before introducing it to the ion selective electrodes. The same sample gives a sodium of 142 mmol/L using a direct (undiluted) ion selective electrode. Assuming acceptable quality control, which of the following is the most appropriate course of action?

A. Report a sodium result of 136 mmol/L
B. Ultracentrifuge the sample and repeat by ISE
C. Dilute the sample 1:4 and repeat by ISE
D. Report the undiluted ion selective electrode result

D. Report the undiluted ion selective electrode result

SITUATION: A 2 2S QC error occurs for serum calcium by atomic absorption. Fresh standards prepared in 5.0% w/v albumin are found to be linear, but repeating the controls with fresh material does not improve the QC results. Select the most likely cause of this problem.

A. Matrix effect caused by a viscosity difference between the standards and QC sera
B. Chemical interference caused incomplete atomization
C. Incomplete deconjugation of protein-bound calcium
D. Ionization interference caused by excessive heat

B. Chemical interference caused incomplete atomization

SITUATION: A serum osmolality measured in the emergency department is 326 mOsm/kg. Two hours later, chemistry results are:
Na = 135 mmol/L
BUN = 18 mg/dL
glucose = 72 mg/dL
measured osmolality = 318 mOsm/kg
What do these results suggest?

A. Laboratory error in electrolyte or glucose measurement
B. Drug or alcohol intoxication
C. Specimen misidentification
D. Successful rehydration of the patient

B. Drug or alcohol intoxication

When calibrating a pH meter, unstable readings occur for both pH 7.00 and 4.00 calibrators, although both can be set to within 0.1 pH unit. Select the most appropriate course of action.

A. Measure the pH of the sample and report to the nearest 0.1 pH
B. Replace both calibrators with unopened buffers and recalibrate
C. Examine the reference electrode junction for salt crystals
D. Move the electrodes to another pH meter and calibrate

C. Examine the reference electrode junction for salt crystals

A method calls for extracting an acidic drug from urine with an anion exchange column. The pKa of the drug is 6.5. Extraction is enhanced by adjusting the sample pH to:

A. 8.5
B. 6.5
C. 5.5
D. 4.5

A. 8.5

SITUATION: A patient who has a positive urinalysis for glucose and ketones has a glycated Hgb of 4.0%. A fasting glucose performed the
previous day was 180 mg/dL. Assuming acceptable QC, you would:

A. Report the glycosylated Hgb
B. Request a new specimen and repeat the glycosylated Hgb
C. Perform a Hgb electrophoresis on the sample
D. Perform a glucose measurement on the sample

B. Request a new specimen and repeat the glycosylated Hgb

Quality control results for uric acid are as follows:
—Run- 1 Run- 2 Run- 3- Run 4- Mean- s
QC1- 3.5- 3.8- 4.1- 4.2 mg/dL- 3.6 mg/dL- 0.40
QC2- 6.8- 7.2- 7.4- 7.5 mg/dL- 7.0 mg/dL- 0.25
Results should be reported from:

A. Run 1 only
B. Runs 1 and 2
C. Runs 1, 2, and 3
D. Runs 1, 2, 3, and 4

C. Runs 1, 2, and 3

SITUATION: A peak blood level for orally administered theophylline (therapeutic range 8-20 mg/L) measured at 8 a.m. is 5.0 mg/L. The preceding trough level was 4.6 mg/L. What is the most likely explanation
of these results?

A. Laboratory error made on peak measurement
B. Specimen for peak level was collected from wrong patient
C. Blood for peak level was drawn too soon
D. Elimination rate has reached maximum

C. Blood for peak level was drawn too soon

SITUATION: Laboratory results on a patient from the emergency department are:
glucose = 1,100 mg/dL
Na = 155 mmol/L
K = 1.2 mmol/L
Cl = 115 mmol/L
TCO2 = 3.0 mmol/L
What is the most likely explanation of these
results?

A. Sample drawn above an IV
B. Metabolic acidosis with increased anion gap
C. Diabetic ketoacidosis
D. Laboratory error measuring electrolytes caused by hyperglycemia

A. Sample drawn above an IV

SITUATION: A patient breathing room air has the following arterial blood gas and electrolyte results:
pH = 7.54
PCO2 = 18.5 mm Hg
PO2 = 145 mm Hg
HCO3 = 18 mmol/L
Na = 135 mmol/L
K = 4.6 mmol/L
Cl = 98 mmol/L
TCO2 = 20 mmol/L
The best explanation for these results is:

A. Blood for electrolytes was drawn above an IV
B. Serum sample was hemolyzed
C. Venous blood was sampled for arterial blood gases
D. Blood gas sample was exposed to air

D. Blood gas sample was exposed to air

SITUATION: The following lab results are reported. Which result is most likely to be erroneous?
Arterial blood gases:
pH = 7.42
pO2 = 90 mm Hg
pCO2 = 38.0 mm
Hg bicarbonate = 24 mmol/L.
Plasma electrolytes:
Na = 135 mmol/L
Cl = 98 mmol/L
K = 4.6 mmol/L
TCO2 = 33 mmol/L

A. pH
B. Na
C. K
D. TCO2

D. TCO2

SITUATION: A patient has the following electrolyte results:
Na = 130 mmol/L
K = 4.8 mmol/L
Cl = 105 mmol/L
TCO2 = 26 mmol/L
Assuming acceptable QC, select the best course of action.

A. Report these results
B. Check the albumin, total protein, Ca, P, and Mg results; if normal, repeat the sodium test
C. Request a new sample
D. Recalibrate and repeat the potassium test

B. Check the albumin, total protein, Ca, P, and Mg results; if normal, repeat the sodium test

A stat plasma lithium determined using an ion-selective electrode is measured at 14.0 mmol/L. Select the most appropriate course of action.

A. Immediately report this result
B. Check sample for hemolysis
C. Call for a new specimen
D. Rerun the lithium calibrators

C. Call for a new specimen

SITUATION: A plasma sample from a person in a coma as a result of an automobile accident gave the following results:
Total CK 480 IU/L
CK-MB 8 µg/L
Myoglobin 800 µg/L
Troponin I 0.02 µg/L

What is the best interpretation of these results?
A. The person had a heart attack that caused the accident
B. The accident caused traumatic injury, but no heart attack occurred
C. A heart attack occurred in addition to a stroke
D. It is not possible to tell whether a heart attack occurred because of the extensive trauma

B. The accident caused traumatic injury, but no heart attack occurred

A chromatogram for blood alcohol (GC) gives broad trailing peaks and increased retention times for ethanol and internal standard. This is most likely caused by:

A. A contaminated injection syringe
B. Water contamination of the column packing
C. Carrier gas flow rate that is too fast
D. Oven temperature that is too high

B. Water contamination of the column packing

SITUATION: An amylase result is 550 U/L. A 1:4 dilution of the specimen in NaCl gives 180 U/L (before mathematical correction for dilution). The dilution is repeated with the same results. The technologist should:

A. Report the amylase as 550 U/L
B. Report the amylase as 720 U/L
C. Report the amylase as 900 U/L
D. Dilute the sample 1:10 in distilled water and repeat

B. Report the amylase as 720 U/L

SITUATION: A patient’s biochemistry results are:
ALT = 55 IU/L
AST = 165 IU/L
glucose = 87 mg/dL
LD = 340 IU/L
Na = 142 mmol/L
K = 6.8 mmol/L
Ca = 8.4 mg/dL
Pi = 7.2 mg/dL
Select the best course of action.

A. Report results along with an estimate of the degree of hemolysis
B. Repeat LD but report all other results
C. Request a new sample
D. Dilute the serum 1:2 and repeat AST and LD

A. Report results along with an estimate of the degree of hemolysis

A blood sample is left on a phlebotomy tray for 4.5 hours before it is delivered to the laboratory. Which group of tests could be performed?

A. Glucose, Na, K, Cl, TCO2
B. Uric acid, BUN, creatinine
C. Total and direct bilirubin
D. CK, ALT, ALP, AST

B. Uric acid, BUN, creatinine

An HPLC assay for procainamide gives an internal standard peak that is 15% greater in area and height for sample 1 than sample 2. The technologist should suspect that:

A. The column pressure increased while sample 2 was being analyzed
B. Less recovery from sample 2 occurred in the extraction step
C. The pH of the mobile phase increased during chromatography of sample 2
D. There was more procainamide in sample 1 than sample 2

B. Less recovery from sample 2 occurred in the extraction step

After staining a silica gel plate to determine the L/S ratio, the technologist notes that the lipid standards both migrated 1 cm faster than usual. The technologist should:

A. Repeat the separation on a new silica gel plate
B. Check the pH of the developing solvent
C. Prepare fresh developing solvent and repeat the assay
D. Reduce solvent migration time for all subsequent runs

C. Prepare fresh developing solvent and repeat the assay

A quantitative urine glucose was determined to be 160 mg/dL by the Trinder glucose oxidase method. The sample was refrigerated overnight. The next day, the glucose is repeated and found to be 240 mg/dL using a polarographic method. What is the most likely cause of this discrepancy?

A. Poor precision when performing one of the methods
B. Contamination resulting from overnight storage
C. High levels of reducing substances interfering with the Trinder reaction
D. Positive interference in the polarographic method caused by hematuria

C. High levels of reducing substances interfering with the Trinder reaction

SITUATION: Results of an iron profile are:
serum Fe = 40 µg/dL
TIBC = 400 µg/dL
ferritin = 40µg/L
transferrin = 300 mg/dL
(reference range 15-200)
These results indicate:

A. Error in calculation of TIBC
B. Serum iron falls before ferritin in iron deficiency
C. A defect in iron transport and not Fe deficiency
D. Excess release of ferritin caused by injury

D. Excess release of ferritin caused by injury

SITUATION: Results of an iron profile are:
Serum Fe = TIBC = ferritin =
40 µg/dL 400 µg/dL 50 µg/L
All of the following tests are useful in establishing a diagnosis of Fe deficiency except:

A. Protein electrophoresis
B. Erythrocyte zinc protoporphyrin
C. Serum transferrin
D. Hgb electrophoresis

D. Hgb electrophoresis

Serum protein and immunofixation electrophoresis are ordered on a patient. The former is performed, but there is no evidence of a monoclonal protein. Select the best course of action.

A. Perform quantitative Ig G, A, M
B. Perform the IFE on the serum
C. Report the result; request a urine sample for protein electrophoresis
D. Perform IFE on the serum and request a urine sample for IFE

C. Report the result; request a urine sample for protein electrophoresis

SITUATION: Hgb electrophoresis is performed and all of the Hgbs have greater anodal mobility than usual. A fast Hgb (Hgb H) is at the edge of the gel and bands are blurred. The voltage is set correctly, but the current reading on the ammeter is too low. Select the course of action that would correct this problem.

A. Reduce the voltage
B. Dilute the buffer and adjust the pH
C. Prepare fresh buffer and repeat the test
D. Reduce the running time

C. Prepare fresh buffer and repeat the test

A technologist is asked to use the serum from a clot tube left over from a chemistry profile run at 8 a.m. for a stat ionized calcium (Cai) at 11 a.m. The technologist should:

A. Perform the assay on the 8 a.m. sample
B. Perform the test only if the serum container was tightly capped
C. Perform the assay on the 8 a.m. sample only if it was refrigerated
D. Request a new sample

D. Request a new sample

A patient’s biochemistry results are:
Na = 125 mmol/L
Cl = 106 mmol/L
K = 4.5 mmol/L
TCO2 = 19 mmol/L
chol = 240 mg/dL
triglyceride = 640 mg/dL
glucose = 107 mg/dL
AST = 16 IU/L
ALT = 11 IU/L
amylase = 200 U/L
Select the most likely cause of these results.

A. The sample is hemolyzed
B. Serum was not separated from cells in sufficient time
C. Lipemia is causing in vitro interference
D. The specimen is contaminated

C. Lipemia is causing in vitro interference

A gastric fluid from a patient suspected of having taken an overdose of amphetamine is sent to the laboratory for analysis. The technologist should:

A. Perform an EMIT assay for amphetamine
B. Refuse the sample and request serum or urine
C. Dilute 1:10 with H2O and filter; perform TLC for amphetamines
D. Titrate to pH 7.0, then follow procedure for measuring amphetamine in urine

C. Dilute 1:10 with H2O and filter; perform TLC for amphetamines

SITUATION: Results of biochemistry tests are:
Na = 138 mmol/L
K = 4.2 mmol/L
Cl = 94 mmol/L
TCO2 = 20 mmol/L
glucose = 100 mg/dL
T bili = 1.2 mg/dL
BUN = 6.8 mg/dL
creat = 1.0 mg/dL
albumin = 4.8 g/dL
T protein = 5.1 g/dL
What should be done next?

A. Request a new specimen
B. Repeat the total protein
C. Repeat all tests
D. Perform a protein electrophoresis

B. Repeat the total protein

The following chart compares the monthly total bilirubin mean of Laboratory A to the monthly mean of Laboratory B, which uses the same control materials, analyzer, and method.
Level 1 Control- Level 2 Control-
Mean(mg/dL) CV (%)
Lab A 1.1 mg/dL 2.1%- 6.7 mg/dL 3.2%
Mean (mg/dL) CV (%)
Lab B 1.4 mg/dL 2.2% 7.0 mg/dL 3.6%
Both laboratories performed controls at the beginning of each shift using commercially prepared liquid QC serum stored at -20°C. Which of the following conditions would explain these differences?

A. Improper handling of the control material by Laboratory A resulted in loss of bilirubin due to photodegradation
B. The laboratories used a different source of bilirubin calibrator
C. Laboratory B obtained higher results because its precision was poorer
D. Carryover from another reagent falsely elevated the results of Laboratory B

B. The laboratories used a different source of bilirubin calibrator

After installing a new analyzer and reviewing the results of patients for 1 month, the lead technologist notices a greater frequency of patients with abnormally high triglyceride results. Analysis of all chemistry profiles run the next day indicated that triglyceride results are abnormal whenever the test is run immediately after any sample that is measured for lipase. These observations point to which type of error?

A. Specificity of the triglyceride reagents
B. Precision in pipetting of lipemic samples
C. Bias caused by sequence of analysis
D. Reagent carryover

D. Reagent carryover

SITUATION: A digoxin result from a stable patient with a normal electrocardiogram (EKG) is reported as 7.4 ng/mL (URL 2.6 ng/mL) using an immunofluorescent method. Renal function tests were normal and the patient was not taking any other medications. The assay was repeated and results were the same. The sample was frozen and sent to a reference laboratory for confirmation. The result was 1.6 ng/mL measured by a competitive chemiluminescent procedure. Which best explains the discrepancy in results?

A. The fluorescent immunoassay was performed improperly
B. Digoxin was lower by the chemiluminescent method because it is less sensitive
C. An interfering substance was present that cross-reacted with the antibody in the fluorescent immunoassay
D. Freezing the specimen caused lower results by converting the digoxin to an inactive metabolite

C. An interfering substance was present that cross-reacted with the antibody in the fluorescent immunoassay

Analysis of normal and abnormal QCs performed at the beginning of the evening shift revealed a 22s error across levels for triglyceride. Both controls were within the 3s limit. The controls were assayed again, and one control was within the acceptable range and the other was slightly above the 2s limit. No further action was taken and the patient results that were part of the run were reported. Which statement best describes this situation?

A. Appropriate operating procedures were followed
B. Remedial evaluation should have been taken, but otherwise, the actions were appropriate
C. Corrective action should have been taken before the controls were repeated
D. The controls should have been run twice before reporting results

C. Corrective action should have been taken before the controls were repeated

The following results are reported on an adult male patient being evaluated for chest pain:
Myoglobin Troponin I CK-MB
(Cutoff = (Cutoff = (Cutoff =
100 µg/L) 0.03 µg/L) 4 µg/L)
Admission 12 µg/L 1.1 µg/L 18 µg/L
3 hours 360 µg/L 1.8 µg/L 26 µg/L
postadmission
6 hours 300 µg/L 2.4 µg/L 40 µg/L
postadmission
What is the most likely cause of these results?

A. The wrong sample was assayed for the first myoglobin
B. The patient did not suffer an MI until after admission
C. Hemolysis caused interference with the 3-hour and 6-hour myoglobin result
D. The patient is experiencing unstable angina

A. The wrong sample was assayed for the first myoglobin

A biochemical profile routinely performed bimonthly on a renal dialysis patient showed a decreased serum calcium and decreased PTH level. Such a lab result may be explained by which of the following circumstances?

A. Malignancy
B. Aluminum toxicity
C. Hypervitaminosis D
D. Acidosis

B. Aluminum toxicity

Hemoglobin electrophoresis performed on agarose at pH 8.8 gives the following results:
A2 Position S Position F Position A Position
35% 30% 5% 30%
All components of the Hgb C, S, F, A control hemolysate were within the acceptable range. What is the most likely cause of this patient’s result?

A. HgbLepore
B. Hgb S-β-thalassemia (Hgb S/β+)
C. Hgb SC disease post-transfusion
D. Specimen contamination

C. Hgb SC disease post-transfusion

Which set of the following laboratory results is most likely from a patient who has suffered an AMI? Reference intervals are in parenthesis.
Total CK | CK-MB | CK index
(10-110 U/L) (1-4 µg/L) (1%-2.5%)
A. 760 U/L 16 µg/L 2.1%
B. 170 U/L 14 µg/L 8.2%
C. 160 U/L 4 µg/L 2.5%
D. 80 U/L 2 µg/L 2.5%

B. 170 U/L 14 µg/L 8.2%

Na K Cl HCO3 BUN Glucose Creatinine Uric Acid
140 mmol/L 5.8 mmol/L 102 mmol/L 18 mmol/L 2.6 mg/dL 20 mg/dL DL DL
132 mmol/L 4.8 mmol/L 98 mmol/L 24 mmol/L DL DL DL DL
Two consecutive serum samples give the results shown in the table above (at the top of this page) for a metabolic function profile. The instrument is a random access analyzer that uses two sample probes. The first probe aspirates a variable amount of serum for the spectrophotometric chemistry tests, and the second probe makes a 1:50 dilution of serum for electrolyte measurements. What is the most likely cause of these results?

A. Both patients have renal failure
B. There is an insufficient amount of sample in both serum tubes
C. There is a fibrin strand in the probe used for the spectrophotometric chemistry tests
D. The same patient’s sample was accidentally run twice

C. There is a fibrin strand in the probe used for the spectrophotometric chemistry tests

Brainscape's Knowledge GenomeTM

All Questions Flashcards

Brainscape's Knowledge Genome^TM