Clinical Chemistry Flashcards
Act of obtaining a blood sample from a vein using a needle attached to a syringe or a stoppered evacuated tube;
The most common way to collect blood specimens
Venipuncture
Major veins for venipuncture
- Median cubital vein
- Cephalic vein
- Basilic vein
Most common site for venipuncture
antecubital fossa
The ___ pattern is displayed by approximately 70% of the population
H pattern
vein located near the center of the antecubital fossa;
Preferred vein - large and closer to the surface, the most stationary
Easiest and least painful to puncture
Least likely to bruise
Median cubital vein
Second choice vein;
Harder to palate than median cubital vein
Fairly well-anchored;
often the only vein felt in obese patients
Cephalic vein
Last choice of vein
Not well anchored and rolls easily
Increased risk of puncturing a median cutaneous nerve branch or the brachial artery
not recommended unless no other vein in either arm is more prominent
Basilic vein
Veins on the back of the hand and wrist may also be used for venipuncture
True
Veins on the underside of the wrist should never be used for venipuncture
True
Leg, ankle and foot veins are sometimes used but not without permission of the patient’s physician, due to potential for significant medical complications
True
3 Types of Blood specimens
- Serum
- Plasma
- Whole blood
Not normally a clear, pale yellow fluid;
Separated from clotted blood by centrifugation
Many chemistry tests are performed using this specimen
Serum
Non fasting serum can be cloudy due to ____
lipids
Normal clotting time for serum
30 mins
Does serum contain fibrinogen and other coagulation factors?
No
Centrifugation speed and time to obtain serum specimen
10 minutes at an RCF of 1,000 to 2,000 g
Normally a clear to slightly hazy, pale yellow fluid;
Separates from the cells when blood in an anticoagulant tube is centrifuge;
Contains fibrinogen
Plasma
Is fibrinogen present in the plasma
Yes
Fibrinogen is not present in the serum because ___
It was used in clot formation
Stat and other tests requiring a fast Tat are often collected in tubes containing ___ anticoagulant because they can be centrifuged immediately to obtain plasma
Heparin
contains both cells and plasma;
Must be collected in an anticoagulant tube to keep it from clotting;
used for most hematology tests and many POCTs, especially in acute care and Stat situations
Whole blood
3 Methods of venipuncture
- ETS
- Needle and syringe
- Butterfly set
Preferred method of venipuncture because blood is collected from the vein into the tube, minimizing the risk of specimen contamination and exposure to the blood
ETS
discouraged by CLSI due to safety and specimen quality issues; sometimes used on small, fragile or damaged veins
Needle and syringe
Can be used with ETS or a syringe; often used to draw blood from infants and children, hand veins, Difficult-draw situations.
Butterfly set
Restrict venous flow but not arterial flow
Tourniquet
Tourniquets must not be left on longer than
1 minute
Length and width of the tourniquet
1 inch wide x 15 inches long
Gauge and bore are inversely related
True
Gauge considered standard for routine venipuncture
21 gauge
Gauge used for pediatrics
23 gauge
3 basic components of the ETS
Multisample needle, tube holder, evacuated tubes
Includes a plastic syringe, a needle, and a transfer device
Syringe system
23 gauge most commonly used for phlebotomy
Butterfly system
Handheld medical device that helps medical staff visualize veins before phlebotomy.
AccuVein
AccuVein emits ___ and is held about 7 inches over the potential phlebotomy site
infrared light
Tube color without an anticoagulant or additive (Glass itself can activate clotting)
Red
Activates intrinsic pathway
Negatively charged surface
Negatively = iNtrinsic
Extrinsic pathway is activated by
Tissue factor
“Ng dahil Kay EX, kinailangan mo ng TISSUE”
Type of EDTA tube that can shrink RBCs to (Low HCT, Low MCV) , but it can be used for PBS
K3EDTA (liquid form)
More preferred in routine CBC
K2EDTA
Tube color and anticoagulant/additive used for whole blood/ blood bank and molecular diagnostics
Pink (Pray-dried K2EDTA)
Tube color and anticoagulant/additive used for molecular diagnostics
White (EDTA and gel)
Blood to anticoagulant ratio for light blue (sodium citrate)
9:1
More preferred Na citrate concentrations
3.2%
Tube and anticoagulant used for sedimentation rate
Black (sodium citrate)
Blood to anticoagulant ratio for ESR
4:1
Alternative top for ESR
Lavender
Intravenous anticoagulant ;
Universal anticoagulant
Heparin
Top and anticoagulant used for toxicology
Royal blue (sodium heparin, K2EDTA)
Binds magnesium, thus inhibiting the MG-depended enzyme, enolase
Sodium fluoride
Antiglycolytic agent in gray top tube
Sodium fluoride
Anticoagulant in gray top tube
Potassium oxalate
Sterile containing sodium polyanetholesulfonate; used for microbiology culture
Yellow
Top and anticoagulant used blood bank phenotyping and paternity testing
Yellow (acid citrate dextrose)
Top and anticoagulant used for lead testing
Tan (sodium heparin)
Top used for faster clotting (5-10 minus clotting time); contains thrombin
Yellow/ Gray and orange
CLSI Order of Draw
- Sterile tube
- Coagulation tube
- Serum tube with or without clot activator, with or without gel
- Heparin tube with or without gel separator
- EDTA tube with or without gel separator
- Glycolytic inhibitor tube
“Stop, light red! Stay put, Green Light, go!”
Preferred specimen for newborn screening tests
Capillary blood
Length of lancet to be used for capillary puncture
less than 2.0 mm
Sites for capillary puncture
Palmar surface of 3rd and 4th fingers for adults
Lateral plantar heel surface (newborns)
Earlobes (alternative)
Capillary order of Draw
- EDTA specimens
- Other additive specimens
- Serum specimens
For blood gas analysis and pH measurements
Arterial puncture
In arterial puncture, __ are used instead of evacuated tubes because of the pressure in an arterial blood vessel
Syringes
Preferred anticoagulant for arterial puncture
Heparin
Arterial puncture collects without a tourniquet
True
Primary arterial sites (in order of preference)
Radial, brachial, femoral arteries
Major complications of arterial puncture
Thrombosis, hemorrhage, and possible infection
Done before collecting an arterial blood from Radial artery to determine whether the ulnar artery can provide collateral circulation to the hand after the Radial artery puncture
Modified Allen Test
Peaks at 4-6 AM;
lowest at 8 PM - 12 AM;
50% lower at 8PM than at 8 AM
Cortisol
Peaks early to late morning; decreased up to 30% during the day
Iron
Increased after recent food ingestion
Glucose, insulin, TAG, gastrin, ionized calcium
Decreased after recent food ingestion
Chloride, phosphorus, potassium, amylase, ALP
T or F
Potassium doesn’t increase post prandially, thus it does not require fasting
T
Increased when an individual is stressed
ACTH, cortisol, catecholamines, prolactin
What is the first to increase during stress?
Catecholamines
Array of signs and symptoms resulting from increased cortisol
Cushing’s syndrome
Elevated ACTH from the pituitary gland resulting to increased cortisol
Cushing disease
Require fasting
FBS, GTT, TAG, LP, Gastrin, Insulin, Ald/Renin
Require Ice (immediate cooling)
Lactic acid, ammonia, blood gas (if not cooled = decreased pH and pO2)
“LAB ICE”
Increased when an hemolysis occurs
Potassium, pO4, Fe, Mg, ALT, AST, LD, ALP, Cathecolamines, CK (marked hemolysis)
Ideally, specimens must be delivered to the laboratory within ___ of collection
45 minutes
Specimens must be centrifuged within ___ of arrival if serum or plasma is needed
1 hour
Maximum time limit for serum or plasma separation is ___ after collection
2 hours
Medical term meaning “immediately” (from the Latin “statim”)
Stat collections
Given the highest priority and are usually ordered from the emergency department and critical care units
Stat collections
Analytical patient testing activities provided within the institution, but performed outside the physical facilities of the clinical laboratories
POCT
Laboratory testing tat is performed outside the central or core laboratory and generally at the site of clinical care or close to the patient
POCT
The highest volume POCT in most health care institutions
POC glucose
A drop of blood most frequently obtained via ___ is applied to a test strip
capillary puncture
Common POCTs (Tests requiring immediate decisions)
Glucose, blood gases, cardiac markers, urinalysis, creatinine, PT/INR, Infectious diseases (HIV, RSV, influenza), drug screening
Most common error in specimen collection
Misidentification of patient
Most common reason for specimen rejection
Hemolysis or lipemia
Next most common fluid for determination after blood; quantitative analysis require timed samples (usually 24 hours)
Urine
assess fetal lung maturity, congenital diseases, hemolytic diseases, genetic defects, gestational age
Amniotic fluid
Specifications established by the ACS
Suitable for use in most analytic laboratory procedures
Analytical Reagent
Additional purification steps
For use in specific procedures such as chromatography, atomic absorption, immunoassays, molecular diagnostics, standardization or other techniques that require extremely pure chemicals
Ultrapure
Used to manufacture drugs; Purity criterion are not based on laboratory needs
United Stated Pharmacopeia / National Formulary
Impurity specifications are not stated
Chemically pure or pure grade
Used primarily in manufacturing and should never be used in the clinical laboratory
Technical/ Commercial Grade
Highly purified chemical that can be measured directly to produce a substance of exact known concentration and purity
Primary standard
substance of lower purity with concentration determined by comparison with a primary standard
Secondary standard
Type of water purity having the most stringent requirements and generally suitable for routine laboratory use.
Type I water
Pipet design that holds or contains a particular volume but does not dispense that exact volume
To contain
Pipet design that will dispense the volume indicated
To deliver
Continuous etched ring or two small, close continuous rings located near the top of the Pipet
Blowout
allows the contents of the Pipet to drain by gravity
Self-draining
Measuring or graduated pipets
Serologic
Mohr
Bacteriologic
Ball, Kolmer or Kahn
Micropipet
“SMBBM”
Transfer pipets
Volumetric
Ostwald-Folin
Pasteur pipets
Automatic macropipet or micropipet
“VOPA”
Graduation marks to the tip; generally a blowout pipet
Serologic
No graduations to the tip; self-draining, but the tip should not be allowed to touch the vessel while the Pipet is draining
Mohr
Pipet with a total holding of less than 1 ml
Micropipet
Dispense or transfer aqueous solutions; self-draining
Volumetric
For biologic fluids having a viscosity greater than that of water; blow out
Ostwald-Folin
Pipet with no calibration marks
Pasteur Pipets
Most routinely used Pipet
Automated macropipet or micropipets
2 types of automated pipets
Air-displacement and positive displacement
Piston-operated devices. A disposable, onetime use polypropylene tip is attached to the Pipet barrel. The Pipet tip is placed into the liquid to be aspirated and is drawn into and dispensed from this tip
Air-displacement
Use a capillary tip that may be siliconized galss, glass, or plastic. this type of Pipet is useful if a Reagent reacts to plastics. Used a Teflon-tipped plunger that fits tightly inside the capillary. The tips are reusable, and carry-over is negligible if the Pipet is properly maintained. Some procedures require a washing or flushing step between samples.
Positive-displacement pipets
Used to dispense a particular volume of liquid during titration
Burets
Sometimes used to transfer small volumes in blood gas analysis or in separation techniques such as chromatography or electrophoresis
Syringes
hygroscopic substances used as excellent drying substances; used to prevent moisture absorption by chemicals, gases, and instrument components
Desiccant
Closed, airtight chamber used with Desiccant
Desiccator
Required for preparation of primary standards; the mechanical analytic balance is also known as a substitution balance
Analytic balances
Single-pan balances that use electromagnetic force to counter balance the weighed samples mass
Electronic balances
Allows the tubes to attain a horizontal position when spinning and a vertical position when the head is not moving
Can attain speeds of up to approximately 3000 rpm –> excessive heat buildup due to increased air friction
Horizontal or swinging bucket
Having angled compartments for the tubes and allow small particles to sediment more rapidly
Angle is fixed at around 52 degrees
common in the laboratory
Fixed-angle or angle-head
High speed centrifuge used to separate layers of different specific gravities
they are commonly used to separate lipoproteins (used in the reference method for lipoproteins quantitation)
Chamber is refrigerated to counter heat produced through friction
Ultra centrifuge
Centrifuge calibration is done every
3 months (quarterly)
Disinfect centrifuge ____
Weekly
Used to check speed of centrifuge
tachometer or strobe light (can also be a timer)
Conversion factor for TAG
0.0113
Conversion factor for AST
0.0167
Conversion factor for Creatinine clearance
0.0167
Conversion factor for cholesterol
0.026
Conversion factor for cortisol
0.0276
Conversion factor for glucose
0.0555
Conversion factor for uric acid
0.0595
Conversion factor for vitamin B12
0.0738
Conversion factor for iron
0.179
Conversion factor for calcium
0.25
Conversion factor for phosphorus
0.323
Conversion factor for BUN
0.357
Conversion factor for magnesium
0.5
Conversion factor for ammonia
0.587
Conversion factor for Bicarbonate
1
Conversion factor for chloride
1
Conversion factor for lithium
1
Conversion factor for osmolality
1
Conversion factor for potassium
1
Conversion factor for sodium
1
Conversion factor for folic acid
2.27
Conversion factor for albumin
10
Conversion factor for hemoglobin
10
Conversion factor for total protein
10
Conversion factor for Thyroxine
12.9
Conversion factor for bilirubin
17.1
Conversion factor for creatinine
88.4
Method of determining the concentration of substance in solution by measuring the amount of light absorbed by that solution after appropriate treatment
Spectrophotometry
Photons travelling in waves
electromagnetic radiation
distance between 2 peaks; inversely related to energy
wavelength
distance between peak and trough (height of the wave)
amplitude
Visible light falls between
400 nm to 700 nm
Range of infrared light
> 700 nm
Range of UV light
<400 nm
Wavelength of red light
around 600 - 700 nm
States that the concentration of a substance is directly proportional to the amount of light absorbed or inversely proportional to the logarithm of the transmitted light
Beer-Lambert Law (Beer’s Law)
Most common source of light for work in the visible and near infrared regions
Incandescent tungsten or tungsten-iodide lamp
Light source Most commonly used for UV work
Deuterium - discharge lamp and Mercury-arc lamp
Isolates the desired wavelength
Monochromators
Most commonly used as monochromators
Diffraction gratings
Contains the sample
Sample cell/cuvette
Has an advantage over round cuvets in that there is less error from the lens effect, orientation in the spectrophotometer, and refraction
Square sample cell
Sample cell used for applications in the visible range
Glass
Sample cell used for applications requiring UV radiation
Quartz
Used in instruments designed to be extremely sensitive to very low light levels and light flashes of very short duration
Photomultiplier tube
Parameters routinely monitored in Spectrophotometry
Wavelength or photometic accuracy, absorbance check, linearity, stray light
Photometric accuracy can be assessed easily using ___
special glass-type optical filters
Filter that has abroad absorption peak around 600 nm
Didymium glass
Filter that has multiple absorption peaks with a sharp peak occurring at 360 nm
Holmium oxide
Performed using glass filters or solutions that have known absorbance values for a specific wavelength
Absorbance check
The ability of a photometric system to yield a linear relationship between the radiant power incident upon its detection and the concentration
Linearity
The linearity of a spectrometer can be determined using __
optical filters or solutions that have known absorbance
Any light that impinges upon the detector that does not originate from a polychromatic light source
Stray light
Stray light can be evaluated by using
special cut off filters
Measures the quantity of light reflected by a liquid sample that has been dispensed onto a grainy or fibrous solid support
Reflectometry
Applications of Reflectometry
Urine dipstick analysis,
Dry slide chemical analysis
Measurement of concentration is done by detecting the absorption of electromagnetic by atoms rather than molecules. when a ground state atom absorbs light energy, an excited atom is produced. the excited atom then returns to the ground state, emitting light of the same energy as it absorbed
Atomic Absorption Spectrophotometry
Components of AAS
Hollow-cathode lamp, Flame, Monochromator
Usual light source in AAS
Hollow-cathode lamp
Breaks chemical bonds and form free, unexcited atoms; serves as sample cells (instead of a cuvet)
Flame
Used to isolate the desired wavelength; also protects photo detector from excessive light emanating from flame emissions
Monochromators
Application of AAS
Measurement of unexcited trace metals (calcium and magnesium)
Measurement of light emitted by excited atoms
Flame photometry
Application of Flame Photometry
Determine the concentration of Na, K, Li
Lithium (Flame with characteristic color)
Red
Sodium (characteristic color in FP)
Yellow
Magnesium characteristic color in FP
Blue
Rubidium characteristic color in FP
Red
Potassium characteristic color in FP
Violet
Measurement of the concentration of solutions that contain fluorescing molecules
Fluorometry
Most common light source in fluorometry
Xenon lamp
Application of fluorometry
in Drugs
Chemical energy generated in a chemiluminiscent reaction produces excited intermediates that decay to a ground state with the emission of photons; no excitation is required unlike in fluorometry
Chemiluminescence
made with a Spectrophotometer to determine concentration of particulate matter in sample. The amount of light blocked by a suspension of particles depends not only on concentration but also on size
Turbidimetry
Applications of turbidimetry:
Detection of bacterial growth and bacterial culture
Antibiotic sensitivity
Coagulation studies
Protein concentration in CSF and urine
True
Light scattered by small particles is measured at an angle to the beam incident to the cuvet. Measure particles that are too large for spectrophotometry, such as antibody-antigen complexes formed in enzyme immunoassays.
Nephelometry
Involves measurement of the current or voltage generated by the activity of specific ions.
Electrochemistry
Analytic techniques involved in electrochemistry
Potentiometry
Coulometry
Voltammetry
Amperometry
Measurement of potential (voltage) between 2 electrodes in a solution to measure analyte concentration
Potentiometry
Applications of potentiometry
pH, pCO2, Na, Ca, K, NH4
Measurement of the current flow produced by an oxidation-reduction reaction
pO2 (Clark electrode), glucose, peroxidase
Electrochemical titration in which the titrant is electrochemical generated
Coulometry
Application of coulometry
chloride
Potential is applied to an electrochemical cell and the resulting current is measured
Voltammetry
Applications of voltammetry
Anodic stripping Voltammetry (for lead and iron)
Separation of charged compounds based on their electrical charge
Electrophoresis
Most commonly used support medium in electrophoresis
cellulose acetate
maintains pH
Buffer
Movement of buffer ions and solvent relative to the fixed support
Electroendosmosis
Most common and reliable way for quantitation of separated protein fractions
Densitometry
Separation of complex mixtures on the basis of different physical attractions between the individual compounds and the stationary phase of the system
Chromatography
Components of chromatography
Mobile phase
Stationary phase
Column
Eluate
It carries the complex mixture in chromatography
Mobile phase
Substance through which the mobile phase flows
Stationary phase
Holds the stationary phase
Column
separated components in chromatography
Eluate
uses pressure for faster separations
High-Performance Liquid Chromatography
Separate mixtures of compounds that are volatile or can be made volatile
Gas-Chromatography
Sample in a __ is first volatilized and ten ionized to form charged molecular ions and fragments that are separated according to their mass-to-charge ratio
Mass Spectrometry
Application:
Allows definitive identification when used on samples eluting from GC or HPLC
Gold standard for drug testing when coupled with GC
Mass Spectrometry
Two-step procedure or MALDI-TOF
- MALDI
- Time-of-flight (TOF)
A laser pulse irradiated the sample, causing desorption and ionization for both the matrix and the sample
MALDI-TOF MS
The molecular weight of the proteins acquired by mass Spectrometry is used to determine the identity of the sample and is helpful in determining post translational modifications that may have occurred
MALDI-TOF MS
Analysis of biomolecules such as peptides and proteins (application of MALDI-TOF MS
True
Three basic approaches with instruments
Continuous flow, centrifugal analysis, and discrete analysis
large number of specimens in one run
Batch analysis
Analyzer that offers random-access or Stat capabilities
Discrete analyzers
Type of analysis which uses air bubbles in the sample and Reagent streams. Air is injected into each stream as a series of small bubbles which travel along with the reaction system. The air bubbles minimize diffusion of reagents and mixing between samples preserving the integrity of each individual reaction
Continuous-Flow Analysis
Sample and Reagent are placed in a rotor. When centrifugal force is applied, the rotor spins and causes the two components to flow into a reaction chamber where they combine to form a product.
Centrifugal analysis
Slides contain all the materials necessary for a single analysis. No reagents were needed to prepare the slide for use
Dry-slide technology
Composition of a dry slide
Spreading layer
Scavenger layer
Reagent layer
Indicator layer
Support layer
Point of contact with the sample.
Spreads the sample equally over a defined area. Also serves as a sieve
Spreading layer
Optional layer. Removes materials present into the sample which may interfere with the reaction. Example: slide for uric acid containing ascorbate oxidase to remove Vitamin C
Scavenger layer
Optional layer. Contains a dye or some other type of indicator which reacts with the products of reaction taking place in the Reagent layer, forming a colored complex
Indicator layer
Should be translucent to allow light used in reflectance spectroscopy to pass through
Support layer
Light of a selected wavelength shines through the bottom of the cell. the light beam, reflects off the underside of the spreading layer and passes through the Reagent and indicator layers to a photodetector. Any absorbance which takes place must be due to the colored material formed by reactions in the slide
Reflectance Spectroscopy
Instrument analysis patient samples only for those constituents specifically ordered and Stat samples can be carried out by momentarily interrupting the normal sequence of patient analyses. The instrument must also be capable of incorporating new tests into the Analytical scheme by addition of appropriate reagents and simple reprogramming for the new test parameters.
Random Access Analysis
All samples are loaded at the same time and a single test is conducted on each sample
Batch testing
More than one test is analyzed concurrently on a given clinical specimen
Parallel testing
Multiple tests analyzed one after the another on a given clinical specimen
Sequential testing
Reagents from other manufacturers may be used
Open Reagent system
Operator can only use manufacturer’s reagents
Closed Reagent system
Process by which lab ensures quality results by closely monitoring preanalytical, analytical, and postanalytical stages of testing
Quality assurance
Everything that precedes test performance
Preanalytical
Everything related to assay
Analytical
Everything that comes after test analysis
Postanalytical
Comparing results from current to previous
Delta check
Part of analytical phase of quality assurance; process of monitoring results from control samples to verify accuracy of patient results
Quality control
Controls are run __
Daily
Difference between highest and lowest value; easiest measure of spread
Range
Most frequently used measure of variation
Standard deviation
An index of precision used to compare the dispersion of two or more groups of data with different units or concentrations
Coefficient of variation
Used to determine if there is a significant difference between the means of two groups pf data (Compares accuracy)
T- test
ATM
Accuracy
T-test
Mean
Used to determine if there is a significant difference between the SD of two groups of data (compares precision)
F-test
SPF
SD
Precision
F-test
Describes many continuous laboratory variables and shares several unique characteristics
Gaussian Distribution (Normal Distribution)
In the Normal Distribution, the mean , median, mode are identical
True
The distribution In the Normal Distribution curve is symmetric (Bell Curve)
True
The total area under the Gaussian curve is __
1.0 or 100%
The ____ summarizes relations between the area under the Gaussian distribution and the SD
68-95-99 Rule
___% of data fall between 1 +/- SD from the mean
68
___% of the data fall between +/- 2 SDs from the mean
95
__% fall between +/- 3SDs from the mean
99
Nearness or closeness of assayed values to the true value
accuracy
Nearness or closeness of assayed values to each other
Precision
Ability of an analytical method to maintain accuracy and precision over an extended period of time
Reliability
degree by which a method can easily be repeated
Practicability
ability to measure the smallest concentration of the analyte of interest
Analytical sensitivity
ability to measure only the analyte of interest
Analytical specificity
Also known as linearity; range of values over which lab can verify accuracy of test system
Reportable range
Formerly called normal value / normal range
Can vary for different patient population
Reference interval
Reference interval is established by testing minimum of __ healthy subjects and determining range in which 95% fall
120
Verifying a reference interval (transference) can require as few as __ study individuals
20
Establishing a new reference interval my require from ___ to as many as ___ study individuals
120 - 700
Transference and validation of a reference interval requires as few as ___ study individuals
40
Reporting a positive result in a patient who has the disease
True Positive
Reporting a positive result in a patient who doesn’t have the disease
False positive
Reporting a negative result in a patient who doesn’t have the disease
True negative
Reporting a negative result in a patient wo has the disease
False negative
% of population with the disease that test positive; ability of the analytical method to detect the proportion of individuals with the disease
Diagnostic sensitivity
% of population without the disease that test negative; ability of the analytical method to detect the proportion of individuals without the disease
Diagnostic specificity
% of time that a positive result is correct
Positive predictive value
% of time that a negative test result is correct
Negative predictive value
assayed on a regular schedule to verify that a laboratory procedure is performing correctly
QC samples
New instrument or new lot of reagents: analyze QC materials for ___ days
20
2 parameters needed for QC
Mean, standard deviation
Other name of Levey-Jennings Control Chart
Shewart plot
Most common representation for evaluating QC results
Levey-Jennings Control Chart
Control values increasing or decreasing for six consecutive runs
Trend
Main cause of a trend
Deterioration of reagents
six consecutive control values ont he same side of the mean
Shift
Main cause of a shift
Improper calibration of the instrument
Highly deviating values; control result outside established limits
Outliers
Warning rule
1(2S)
Present in all measurements; due to chance; no means of predicting it
Random error
error that doesn’t recur in regular pattern
Random error
Associated with violations of the 12s, 13s, and R4s Westgard rules
Random error
Error that influences ALL observations consistently in one direction
Systematic error
Recurring error inherent in test procedure
Systematic error
Associated with violations of the 22s and 41s Westgard rules
Systematic error
Error due to dirty glassware
Random error
Use of wrong pipet
Random error
Voltage fluctuation
Random error
Sampling error
Random error
Anticoagulant or drug interference
Random error
Dirty photometer
Systematic error
Faulty ISE
Systematic error
Evaporation or contamination of standards or reagents
Systematic error
Also known as external quality assessment
Proficiency testing
Consists of evaluation of method performance by comparison of results versus those of other laboratories for the same set of samples
Proficiency testing
Failed Delta check
> 20% deviation
Test results that indicate a potentially life-threatening situation
Critical values
critical or panic values for serum glucose
< 40 mg/dL
> 500 mg/dL
Approach focusing on process improvement as a means to meet a set standard
Quality management
Provides a culture, infrastracture, methodology, and metric for quality improvement
Lean Six Sigma
3 Roles of Lean Six Signa team
Black belts (Project coaches/leaders)
Green belts (Project team members)
Blue belts (Project sponsors)
full time quality improvement leaders who dedicate 100% of their time to proactively addressing process and quality problems
Project coaches/leaders (Black belts)
Contribute 20% of their on project time while maintaining their normal jobs
Project team members (Green Belts)
“20% discount sa Green Belt”
Mid-to-senior level sponsors who review the project, remove organizational barriers, and encourage the team members
Project sponsors (Blue belts)
Uses a problem-cause-solution methodology to improve any process through waste elimination and variation reduction.
Lean Six Sigma
The belief that quality improvement requires sound problem solving
DMAIC Methodology
Meaning of DMAIC
Define, Measure, Analyze, Improve, and Control
Major energy source; storage form of energy; components of cell membranes; structural component in plants, bacteria, insects
Carbohydrates
Where is glycogen stored in the body?
Liver and muscle
Bond that links 2 sugar units
Glycosidic bond
Breakdown polymers to dextrins and dissacharides
Salivary amylase and pancreatic amylase
Glucose + fructose
Sucrose
Glucose + galactose
Lactose
Glucose + glucose
Maltose
____ are absorbed by the gut via active transport (glucose and galactose) or facilitated diffusion (fructose). They are then transported into the liver through the portal circulation
Monosaccharides
___ is the only carbohydrate to be used directly for energy
Glucose
After glucose enters the cell, it undergoes phosphorylation into glucose-6-phosphate through the action of __ or ___
hexokinase or glucokinase
Most common enzyme deficiency in the glycolysis pathway (Embden-Meyerhof pathway)
Pyruvate kinase deficiency
Pyruvate kinase deficiency leads to
Hemolytic anemia
Marker of hypoxia
Lactate
Main purpose of glycolysis
Generates ATP
The Hexose-Monophosphate shunt generates ___
NADPH
NADPH –> reduced
glutathione
Most common enzyme deficiency in the Hexose-Monophosphate shunt
G6PD deficiency
Metabolism of glucose molecule to Pyruvate or lactate for production of energy
Glycolysis
Formation of glucose-6-phosphate from non-carbohydrate sources
Gluconeogenesis
Breakdown of glycogen to glucose for use as energy
Glycogenolysis
Conversion of glucose to glycogen for storage
Glycogenesis
Conversion of carbohydrates to fatty acids
Lipogenesis
Decomposition of fat - ketone production
Lipolysis
G6PD leads to
Hemolytic anemia (Heinz bodies)
Produced by the beta cells of the islets of Langerhans (pancreas)
Insulin
Marker of endogenous insulin production
C-peptide
Prepoinsulin –> Proinsulin –>
Insulin
Hypoglycemic hormone
Insulin
T or F (Physiologic effects of insulin)
Increases utilization of glucose by the cells by increasing cellular uptake and hepatic glycolysis
T
T or F (Physiologic effects of insulin)
Increases glycogenesis and inhibits glycogenolysis
T
T or F (Physiologic effects of insulin)
Inhibits gluconeogenesis
T
T or F (Physiologic effects of insulin)
Stimulates lipogenesis while inhibiting lipolysis
T
T or F (Physiologic effects of insulin)
Stimulates protein synthesis and stimulates uptake of amino acids into muscles
T
Produced by the alpha cells of the islets of Langerhans
Glucagon
BIGADS
Beta cells: Insulin
Glucagon: Alpha cells
Delta cells: Somatostatin
T or F (Physiologic effects of glucagon)
Promotes liver glycogenolysis
T
T or F (Physiologic effects of glucagon)
Increases glyconeogenesis
T
T or F (Physiologic effects of glucagon)
Inhibits glycolysis
T
Increases gluconeogenesis; Decreases glucose uptake and utilization by extra hepatic tissues
Cortisol (Glucocorticoids)
Stimulates glycogenolysis
Catecholamines
Increases glucose absorption in the small intestines
Thyroid hormone
Inhibit glucagon and insulin secretion
Somatostatin
Increases liver gluconeogenesis; inhibits glycolysis; inhibits glucose transport
Growth hormone
Hypercortisolism
Cushing’s syndrome
Pituitary tumor; Increased ACTH; Increased Cortisol
Cushing’s disease
Stress hormones (increases in long-term stress)
Cortisol and Catecholamines
First to increase during stress
Catecholamines
Elevated growth hormone (childhood onset)
Gigantism
Elevated growth hormone (adult onset)
Acromegaly
Heterogenous group of multifactorial, polygenic syndromes characterized by an elevated fasting blood glucose caused by a relative or absolute deficiency in insulin
Diabetes Mellitus
Characterized by an absolute deficiency of insulin caused by an autoimmune attack on the beta cells of the pancreas
Type 1 DM
Characterized by a combination of insulin resistance and dysfunctional beta cells (defective receptors of target cells or organs)
Type 2 DM
Juvenile onset DM / Insulin Dependent DM
Type 1 DM
Adult onset DM / Non-insulin Dependent DM
Type 2 DM
Most common in children and young adults DM
Type 1 DM
Most common with advancing age DM
Type 2 DM
Frequency of Type 1 DM
5 - 10%
Frequency of Type 2 DM
90 - 95%
Autoantibodies in Type 1 DM
Anti-islet cell cytoplasmic antibody
Insulin autoantibodies
Anti-GAD
Genetic has a stronger effect in this Type of DM
Type 2 DM
Pathogenesis: Destruction of pancreatic beta cells, usually autoimmune
Type 1 DM
Pathogenesis: No autoimmunity; insulin resistance and progressive insulin deficiency
Type 2 DM
C- peptide levels in Type 2 DM
Detectable
Type of DM where the plasma insulin is high in early disease; low to absent in disease of long duration
Type 2 DM
Type of DM prone to keto acidosis and diabetic complications due to uncontrolled lipolysis
Type 1 DM
Ketone bodies and their percentages
Beta-hydroxybutyric acid - 78%
Acetoacetic acid - 20%
Acetone - 2%
Glucose intolerance with onset or first recognition during pregnancy
Gestational Diabetes Mellitus
Large % of patients develop DM in GDM within ___ years
5 to 10 years
Screening for GDM
2-hour GTT using a 75 g glucose load
Diagnostic criteria for DM
Random plasma glucose
> /= 200 mg/dl
Diagnostic criteria for DM
Fasting plasma glucose
> /= 126 mg/dl
Diagnostic criteria for DM
Two-h plasma glucose
> /= 200 mg/dl
Symptoms of DM
polyuria, polydypsia, polyphagia
Normal fasting plasma glucose
< 100 mg/dl
Normal 2-hour plasma glucose level (after 75 g load)
< 140 mg/dl
HbA1c prediabetes range
5.7 - 6.4%
Impaired fasting glucose level
100 - 125 mg/dl
Impaired glucose tolerance level
140 - 199 mg/dl
Fasting plasma glucose level for DM
> /=126 mg/dl
2-hour plasma glucose level for DM
> /= 200 mg/dl
Detection of GDM
Oral Glucose Tolerance Test
Before an OGTT is performed, individuals should ingest at least ___ of carbohydrates for 3 days preceding the test
150 g/day
Fasting duration for OGTT
8-14 hours
In OGTT, an FBG greater than ___ necessitates that the test be stopped immediately.
140 mg/dl
Glucose load for adults
75 g
Glucose load for children
1.75 g/kg body weight
Glucose load for pregnant women
75 g or 100 g
Patient should finish glucose load within ___
5 - 15 minutes
Patient should not vomit. If patient vomits, ___
discontinue the test
Gestational diabetes Mellitus is diagnosed if ___ are exceeded
> /= 2 plasma glucose levels
Rate of formation of HbA1c is proportional to the average blood glucose concentration over the previous ___
3 months
For every 1% increase in HbA1c, there is corresponding ___ change in plasma glucose
35 mg/dl
The Ada also recommends that a HbA1c be tested ___ to monitor long-term glycemic control
at least twice a year
False decrease HbA1c
decreased RBC lifespan
Glycated albumin
Fructosamine
Fructosamine monitors glucose control over past ___
2 - 3 weeks
Lifespan of albumin in circulation
20 days
False decrease in Fructosamine testing
Hypoalbuminemia
At about ____, glucagon and other glycemic factors are released
50 - 55 mg/dl
Insulinoma, various liver disorders, and gastrointestinal disorders and surgery all causes hypoglycemia
T
Whipple’s Triad
Fasting hypoglycemia (<50 mg/dl)
Symptoms of hypoglycemia
Immediate relief of symptoms with intravenous glucose
Warning signs and symptoms of hypoglycemia are all related to the central nervous system
True
Test for hypoglycemia in which the glucose values drop around 4 and 5 hours
5-h OGTT
Test for hypoglycemia in which normal individuals can maintain glucose levels at normal levels within 3 days; noticeable drop in blood glucose over the 3 days of the fast
72-h fast
Half-life of albumin
30 days
target HbA1c
7%
Controlled DM
<7%
Uncontrolled DM
> 7%
Controlled DM is tested every
6 months
Uncontrolled DM is tested every
3 months
Standard clinical specimen for glucose testing
Fasting venous plasma
Fasting blood sugar should be obtained after ___ of fasting
8 - 10 hours
Whole blood glucose levels ___ VS plasma levels
10 - 15% lower
Glucose is metabolized at room temperature at a rate of ___
7 mg/dl/hr
At 4 deg C, glucose decreases by approximately ___
2 mg/dl/hr
Evacuated tube for glucose testing
gray top (for long delay)
Anticoagulant in gray top tube
Sodium oxalate
Antiglycolytic agent in gray top tube
Sodium fluoride
Alternative Antiglycolytic agent in gray top tube
Iodoacetate
CSF glucose levels ___ of plasma levels
60 - 70%
As little as 10% contamination with 5% dextrose will elevate glucose in a sample by ___
500 mg/dl or more
Prevention of dextrose contamination.
Stop the line, wait for ___, discard 1st tube, the 2nd tube is used for analysis
5 - 10 mins
CSF glucose ___ in bacterial meningitis
decreases
Methods for Glucose measurement (2)
Chemical, Enzymatic
Method of glucose measurement that relies on the reducing property of sugars
Chemical method
Glucose and other carbohydrates are capable of converting cupric ions in alkaline solution to cuprous ions
Chemical method
Chemical methods of glucose measurement (2)
Oxidation-reduction method and Condensation method
Oxidation-reduction method for glucose measurement (2)
Alkaline Copper Reduction method and Alkaline Ferric Reduction method
Alkaline Copper Reduction method (4)
Folin-Wu
Nelson-Somogyi
Neocuproine method
Benedict’S method
Hagedorn-Jensen method
Alkaline Ferric Reduction method
Dubowski method
Condensation method
Enzymatic methods of glucose measurement (2)
Glucose oxidase method
Hexokinase method
Glucose oxidase method (2)
Colorimetric method and Polarographic method
Most specific enzyme reacting with only beta-D-glucose
Glucose oxidase
Cu + phosphomolybdate –> phosphomolybdenum blue
Folin-Wu
Cu + arsenomolybdate -> arsenomolybdenum blue
Nelson-Somogyi
Glucose oxidase method that uses a side reaction that consumes H2O2
Colorimetric method
Glucose oxidase method that measures the rate of disappearance of oxygen using an oxygen electrode
Polarographic method
Reference method for glucose determination
Hexokinase method
More accurate than glucose oxidase methods Because the coupling reaction using G6PDH is highly specific; therefore it has less interference than the coupled glucose oxidase procedure
Hexokinase method
NADPH has a strong absorbance at ___
340 nm
Hexokinase method is not affected by ascorbic acid or uric acid
T
Most common cause of lactose intolerance
Lactase deficiency
Congenital deficiency of one of three enzymes involved in galactose metabolism, resulting in increased levels of galactose in plasma
Galactosemia
Classic galactosemia; most common; usually presents with hepatomegaly, jaundice, hypoglycemia, convulsions, cataracts and lethargy
Galactose-1-phosphate uridyl transferase
May result in cataract development but otherwise asymptomatic unlike the more severe classic galactosemia
Galactokinase
Result of the deficiency of a specific enzyme that causes an alternation of glycogen metabolism
Glycogen storage diseases
Most common congenital form of glycogen storage disease
Von Gierke Disease
Autosomal recessive disease, characterized by hepatomegaly, severe hypoglycemia, metabolic acidosis, ketonemia, and elevated lactate and alanine; G6P deficiency
Von Gierke Disease
Types of Glycogen storage diseases
“Viagra Pill Causes A Muscle Hardening Tight”
“GG Di Ba MaLi Po”
Von Gierke - Glucose-6-phosphatase
Pompe - Glucosidase
Cori/Forbes - Debranching enzyme
Andersen - Branching enzyme
McArdle - Muscle phorphorylase
Hers - Liver phosphorylase
Tarui’s disease - Phosphorylase
