CLINICAL CHEMISTRY Flashcards
A volumetric pipette has an accuracy of
1:1000
A pipette with a bulb close to the delivery tip is used for viscous fluids
Ostwald-Folin pipette
The etched rings on the top of a pipette means
The last drop is to “blown out” after the pipettes drains
Standard solution from which 99.95% of the chemical can be retrieved
Primary Standards
When preparing solutions
A percent solution can be prepared from a volumetric solution
A solution in which the molecules of solute in solution are in equilibrium with excess undissolved molecules
Saturated
Pure water has a pH of
7.0
A 1x10(-6) N solution of hydrocloric acid (HCl) has a pH of
8.0
A standard term that most specifically describes analytical precision
Coefficient of variation
- Standard Deviation
- Variance
Quality Control should be used with all procedures deterrmine
Reliability
A procedure has a 2SD variation from a mean value. How many values from from a normal population will the 2SD include
95.45%
Material with physical and chemical properties closely resembling the test specimen and containing concentrations of the substances being measured
Control
Optical density, according to Beer’s Law
Directly proportional to the concentration
The difference between serum and plasma is that serum does not contain
Fibrinogen
Two control sera are desirable for each general chemistry procedure. Which of these combinations would be appropriate
Mean of normal range and abnormal (high)
Sodium flouride is used in specimen collection to
Prevent glycolysis
The concentration of oxalate recommended to be used as anticoagulant, in mg/ml blood
1-2
Ethylenediamine tetraacetic acid (EDTA) work as anticoagulant by
Chelating Calcium
The venipuncture site for a routine puncture is commonly cleaned with:
70% alcohol
The one precaution to be followed with a specimen for bilirubin determination is to
Protect from light
Substances cannot be preserved by feezing
Lactic dehydrogenase
Serum iron should be drawn at the same time on successive days to avoid
Diurnal variation
Proteins soluble in water
Albumin
The Amino Acids are joined together to form chainlike structure through
Peptide bonding
Elements in proteins differentiate this class of substances from carbohydrates and lipids
Nitrogen
Amino Acid cannot rotate polarized light
Glycine
Denaturation of proteins refers to an
Alteration in tertiary structure
The hemoglobin measurement technique employed for blood donor
Flotation technique of Phillips
Refers to the ratio of velocities of light in two different media
Refractive Index
The most anodic protein on electrophoresis at pH 8.6
Albumin
When protein is at its isoelectric point, the protein will have a
Net zero charge
Svedberg(S) number refer to protein
Ultracentrifugation
The macroglobulins belong to what sedimentation class
19.0S
As urine is heated, a precipitate appears 60C and disappears 100C. The substance present is
Bence Jones Protein
The process of separating albumin from globulins using sodium sulfate
Salting Out
The conversion of protein nitrogen contain to protein content depends on the factor
6.54
NOT true of the biuret reaction
Is relatively free from interference by lipids and hemolysis
In Acute Renal Failure which non protein nitrogen rises the fastest
Blood urea Nitrogen
Why is bromcresol purple the preferred indicator for albumin dye binding technique?
There is less interference from pigment
Reagent employed in the serum protein determination
Biuret
Reason why hemolyzed serum should not be used for total protein
Hemoglobin is absorbed at the same wavelength as protein of biuret reagent
Turbidity in serum is associated with presence of
Chylomicrons
Glycoproteins and mucoproteins are usually bound to
Galactose and Mannose
NOT glycoproteins
Cryoglobulin
NOT applicable to mucoproteins
Hormones and coagulation proteins are induced in this class
How many immunoglobulin classes are currently recognized
Five
When performing an immunoglobulin electrophoresis, there must be present
Excess antibody and constant trough distance between antibody and antigen
Decrease in Albumin, Increase Gamma globulin
Monoclonal gammopathy
Temperature sensitive proteins
Cryoglobulins
TRUE of Albumin
It is produced by liver
To measure urinary protein you can use
Biuret reagent with trichloroacetic acid pretreatment of urine
An elevated creatinine value is most likely to be accompanied
Elevated BUN, 10x creatinine value
Conversion factor for BUN to urea
2.14
By the urease method, urea is enzymatically converted to
Ammonia
Untreated urine can be used for determination of urea by the diacetyl monoxime method because
the method is not measuring ammonia
Urinary creatinine may be elevated in
Muscle Destruction
The measurement of creatinine is based on the formation of a yellow-red color with:
Alkaline picrate
The classic creatinine reaction
Jaffe
The specificity of the Jaffe reaction can be enhanced by
Adsorption with Lloyd’s reagent
A disease state assoc. with an elevation of serum uric acid
Gout
The most common reagent employed in uric acid methodology by alkaline oxidation
Phosphotungstic Acid
The uricase method for uric acid assays depends on
Ultraviolet absorption peak at 290nm before and after treatment with uricase
The most precise method for amino acid determination
Gasometric ninhydrin reaction
The urea clearance test is an indication of
overall kidney function
The creatinine clearance is based on the assumption that creatinine
Passes into the ultrafiltrate
Most accurate clearance test that measure glomerular filtration
Inulin
Clearance test offers best measure of tubular function
p-aminohippurate (PAH)
determination of osmolality involves measurement of
Freezing Point depression
Patients with borderline blood glucose levels are further investigated by performing
3 hour glucose tolerance test (GTT)
The test that gives a two to three (2-3) month picture of diabetic glucose level
HemoglobinA1C
ensure validity of the glucose tolerance test
- a 150 g/day carbohydrate diet for 3 days prior to the test
- a fasting state before glucose is given
- No undue stress before or during the test
Contamination of the glucose reagent with catalase is a problem with which glucose method
Glucose Oxidase
Based on reduced coenzyme read at 340 nm
Hexokinase methodology (glucose det)
Proteins are precipitated by which of the following reagents in the Folin Wu mtd
Tungstic Acid
The interfering reducing substances in the Folin Wu glucose mtd may be removed by
ZInc-barium precipitation
The copper reduction method for glucose, measurable color is developed though the formation of
Molybdenum blue
The most frequently employed automated method for glucose uses
Reduction of alkaline ferricyanide to ferrocyanide
When sugars are separated by chromatography, the application of anisaldehyde/ sulfuric acid/ ethyl alcohol spray will identify galactose as what color spot
Grey
Seliwanoff’s test detects
Fructose
Xylose excretion is helpful in the determination of
Intestinal malabsorption
Prehepatic bilirubin has which if the following for a protein carrier
Albumin
Increase in indirect reacting bilirubin is suggestive of
Hemoglobin breakdown
Direct reacting bilirubin is
Bilirubin diglucuronide
Bilirubin is converted in the intestines to
Urobilinogen
Interfere with the Evelyn and Malloy method for bilirubin
Hemolysis
The port wine color of some urines can be attributed to
Porphyrins
Para-dimethylaminobenzaldehyde
Ehrlich
Both porphobilinogen and urobilinogen form a red colored compound with Ehrlich’s reagent. Differentiation can be obtained by
Solubility of urobilinogen in chloroform
Bilirubin will develop a violet color after adding
Methyl alcohol
A urine specimen that exhibits yellow foam on being shaken should be suspected of having an increased concentration of
Bilirubin
Biological catalyst
Enzyme
Hemolysis will interfere with all of the following enzyme measurement EXCEPT
Aspartate Aminotransferase
A high alkaline phosphatase level in the presence of other negative liver function tests is indicative of
Obstructive Jaundice
A metal ion is sometimes necessary in an enzymatic reaction to
Act as activator of the enzyme
TRUE of isoenzyme
The electrophoretic property is different for each isoenzyme
As the temperature is increased from 25C to 37C in the aspartate aminotransferase reaction, the activity of the reaction
Almost doubles
The Michaelis-Mentein constant in the rate of conversion of substrate to product is determined by
Substrate concentration and rate of dissociation of enzyme-substrate complex
In zero order reaction, there will be no further increase velocity because
All enzyme is bound to substrate
Lipase catalyzes the hydrolysis of
Glycerides
TRUE of the isoenzyme LD1
Present in the greatest amount in normal heart tissue
Lactate + NAD ——-> Pyruvate + NADH. The catalyst in the reaction is
Lactate Dehyrogenase
Serum creatine kinase is clinically sinificant in disease of
Muscle
Creatine kinase frequently elevated in disorders such as acute myocardial infarction (AMI) and:
Duchenne muscular dystrophy
The kinetic or rate enzymatic methodologies, optical density decreases as
Nicotinamide adenine dinucleotide- reduced form (NADP) is changed to nicotinamide adenine dinucleotide (NAD)
In myocardial infarction, the clinically significant enzymes are
CK, AST and LDH
During a suspected MI, you should perform creatinine phosphokinase isoenzyme and lactate dehydrogenase isoenzymes to demonstrate
MB fraction of CK and the LD 1-2 flip
In Muscular dystrophy, the clinically significant enzymes
CK, Aldolase, AST
Ceruloplasmin is an alpha1 globulin that binds
Copper
Most sensitive enzyme indicator of liver function, particularly in obstructive jaundice
Alkaline Phosphatase
Optimum pH of Acid Phosphatase
5.0
The clinical significant of an elevated acid phosphatase is
Prostatic Disease
If an acid phosphatase test cannot be performed immediately after collection, how should the serum be treated
Either acidify or freeze
Tests for ACP detects levels of the enzyme from tissues such as
Liver, spleen, prostate and platelets
The substrate for the Cherry Crandall lipase method
Olive oil and triolein
Other parameters must be known to properly evaluate calcium
pH and protein
The classic Clark- Collip method for calcium is based on the assumption that calcium will be
Precipitated as an oxalate and converted oxalic acid
In the titration of calcium oxalate with potassium permanganate, the temperature must be maintained at
60-80C
A low parathyroid hormone level will cause
Low serum calcium
In the compleximetric titration (EDTA) mtd for calcium, the pH must be adjusted to prevent
interference by magnesium
Purpose of lanthanium in AAS det of calcium
Will bind phosphate
Low chloride level
- Diabetic acidosis
- Renal Failure
- Prolonged vomiting
Inorganic phosphate can be determined from combination of TCA filtrate and
Molybdate
At a pH of 7.4 most of the inorganic phosphate in the plasma is in which form
HPO4
A phosphorus value of 2.5 mEq/L would be how many mg/dl
4.3
A colometric method for magnesium employs which reagent
Titan yellow
The first step in the serum iron mtd involves
break up of the iron- protein complex
Major extracellular cation
Sodium
Major intracellular cation
Potassium
Internal standard when sodium and potassium are measured by flame photometry
Lithium
In the classic Schales and Schales (mercurimetric titration) mtd for chloride, what substance reacts with the indicator to form a violet color
Excess Hg++
The point of equilibrium bet drug dosage intake and drug elimination
Steady state
A major disadvantage of drug detection by immunoassays
Simultaneous assay of multiple drugs in one specimen is not feasible
Lithium is measured by
Flame photometry
Tricyclic antidepressant
Doxepin
When a kidney stone is tested with sodium cyanide and sodium nitroprusside, the appearance of a magenta color identifies what substance?
Cystine
The sweat chloride test is useful in the diagnosis
Cystic Fibrosis
The use of radioisotopes 51Cr provides a direct measurement of
Red cell mass
The average blood volume for human beings, expressed in ml/kg weight
60
In the coulometric-amperometric mtd for chloride, the amount of chloride is measured by:
Amount of current needed to generate Ag+
In gasometric analysis of CO2, the liberated gas is absorbed with
Sodium Hydroxide
What is the purpose of caprylic alcohol in the gasometric mtd for CO2
To prevent foaming
Normal pH of blood
7.35-7.45
Henderson-hasselbach equation
ph= pka + log dissociated salt (A-)
------------------------------
undissociated salt (HA)Ratio of bicarbonate:carbonic acid in normal plasma
20:1
Most of the CO2 in the blood is present in which form
Bicarbonate ion
What will happen if blood is exposed to air during collection of pH and blood gas studies
pCo2 decreases; pO2 increases
If the glass elecrode of the pH instrument is coated with protein, the pH value will be
Variable
The wavelength at which oxyhemoglobin and reduced hemoglobin have the same absorbance is referred to as the
Isoelectric Point
Appropriate of plotting of a concentration curve
Semi-log paper, plot % units on y axis and standard concentration on x axis
In Spectro quality control, the holmium oxide glass filter is used to assess
wavelenth accuracy
Cuvette use for the ultraviolet range,
Quartz cuvette
Emission of a color when an element is burned
Flame Photometry
Light absorbed at wavelength of resonance line by unexcited atoms
Atomic Absorption Spectro
Light source in AAS
Cathode lamp
Disadvantage encountered in Fluometry
Quenching
To achieve the best levels of sensitivity and specificity, a type of detector system that a gas chromatograph may be coupled to
Mass Spectrophotometer
Automated chemistry systems, whether discrete or continuous flow must include
- unknown
- reagent
- unknown + reagent
- reaction analysis
- calculation
- reporting of results
If an isotype has a half life of 12 hours and an activity of 24 millicuries(mCi), what will be its activity in 36 hours?
3 mCi
Contentrated sulfuric acid has a normality of
36
Mixtures can be separated into individual compounds to be measured on the basis of differences in their physical characteristics
Chromatography
Analytes are measured in a sample by means of tubing diameter and flow rate
Continuou flow analysis
Samples and reagents are pipetted into cuvettes, read in photometer and results are calculated
Discrete Processing System
Major binding protein for T4
Thyroid binding Globulin (TBG)
Purpose of iodine in the protein bound iodine (PBI) mtd
Acts as a catalyst in the ceric-arsenite reaction
A T4 measured as iodine 1.8 mg/dl. To what thyroxine value is it equivalent
2.75
In T4 by radioimmunoassay (RIA), the more thyroxine present in the patient serum
The less amount of radioactive labeled thyroxine bound to antibody
T3 uptake is actually measurement of
TBG
NOT good indications of hypothyroidism
T3 Uptake
Steroids is identified as an 18- carbon compound that possesses a phenolic “A” ring
Estrogens
Estrogen with greatest concentration in urine
Estriol
Standard for 17- ketosteroid determination
Dehydroepiandrosterone
The excretion product of progesterone
Pregnanediol
Contain the 21 carbon atoms of the cyclopentanoperhydrophenanthrene ring
Steroid
Hormone that control reabsorption of sodium in the kidney
Aldosterone
The Kober reaction refers to the pink color resulting from the combination of hot concentrated sulfuric acid and extracted
Estrogens
The Ittrich extraction for estrogens involves the reagent
p-nitrophenol
The Porter-Silber reactions employs phenylhydrazine to detect
Corticosteroid
The zimmerman det of 17-ketosteroid is based on reaction with
Meta- dinitrobenzene
For the measurement of 17-ketogenic steroids (17-Hydroxycorticosteroids), prior treatment with what reagent is required
Sodium bismuthate
Cathecolamines are secreted by
adrenal medulla
Metabolite of epinephrine
Vanillylmandelic Acid
A two hour pregnancy test can measure
Chorionic gonadotropins, beta subunit
TRUE of an immunological test for pregnancy
With the agglutination inhibition mtd, the presence of agglutination means a negative test
which subunit of hCG will give a very specific RIA test for the measurement of hCG
Beta
Specimen use for pregnancy testing
Blood and Urine
An ectopic pregnancy is the one that occurs in the
Fallopian Tube
Human chorionic gonadotropin (hCG) is secreted by
Placenta
The highest level of hCG is occurs in which trimester of pregnancy
First Trimester
A glycoprotein consisting of two non identical non covalently bound subunits
Human chorionic gonadotropin
Some commercial kits now available for pregnancy test incorporate
Monoclonal antibodies
To produce reliable results, at which time should blood specimens for lipids studies be drawn
12-16 hours fasting
The reagent for color development in the Liebermann-Burchard reaction for cholesterol
Acetic anhydride/ sulfuric acid
Composed of ethanol and ether in a ratio of 3:1
Bloor’s reagent
Converts esters to free cholesterol so that all measured chole is of the same type
Saponification
Precipitate free cholesterol
Digitonin
Blood cholesterol in hypothyroidism
Increase
Friedewald Formula
LDL chole= TC- (TG/5 + HDL chole)
Coronary Risk Index includes
Total Cholesterol and HDL Cholesterol
Most triglycerides procedures involve measurement of
Glycerol
Lipids with the lowest density
Chylomicrons
Migration sequence from the origin of lipoprotein
Chylo, beta, pre-beta, alpha
Disease associated with elevated beta lipoprotein
Cardiovascular
