exam 4 Flashcards
what is the substance for the enzyme aspartate amino transferase (AST)
aspartate
alpha ketoglutamic acid
creatinine is formed from the breakdown of what
creatine
PSP is removed from the blood by what
kidneys
what is the principle of the Berthelot reaction and what substances can cause falsely elevated values in the reaction?
hydrolysis of urea to ammonium carbonate by enzyme urease ammonia. ammonium reacts with phenol and sodium hypochlorite to form a BLUE colored indophenol. Sodium nitroprusside serves as the catalyst
ammonium, lipemia, icteric specimens
increased ALT values are associated with dieases of the what
liver
what is the normal values for serum AST at 37 C
5-35 IU/L
which anticoagulant should NOT be used for urease testing?
sodium fluoride
what is the normal percentage for the CK-MB isoenzyme?
less than 6%
what reagent is used in the measurement of uric acid?
phosphotungstic acid
creatinine clearance is used to assess the rate of what
glomerular filtration
creatinine clearance formula
CrCl= (UaVu) / (PaT)
what additional information must be known for the CrCl formula if the patient is a infant, young child, or adolescent
body surface area
what is the most common endogenous substance used to assess the glomerular filtration rate
creatinine
what is the most common exogenous substance used to assess the glomerular filtration rate
inulin
serum creatine kinase is most often elevated in diseases of what?
muscle tissue
serum lipase levels are elevated in diseases of what?
pancreas
Diacetyl Monoxime reacts with ____ to produce a yellow product.
urea
what is uremia?
retention of urea and abnormal substances in the blood
what is the normal value for CK in males at 37 C
15-160 IU/L
name three ways that can be used in the laboratory to measure the rate of an enzymatic reaction and give the general term that can be applied to two of the three methods
multiple point assay
continuous monitoring method
both called kinetic
define international unit (IU)
catalyzes one micromole (umol)/ minute of substrate
what is the peak absorbance of reduced NAD (NADH)?
340 nm
the jaffe reaction is used to measure what?
creatinine
which non-protein nitrogen component compromises the largest fraction of NPN in the blood?
urea
BUN
which enzyme is useful in the detection of insecticide poisoning?
pseudocholinesterase
low levels of which enzyme can cause a patient to be susceptible to prolonged apnea when exposed to certain types of anesthesia?
pseudocholinesterase
increased levels of LD-4 and LD-5 are associated with what?
liver/ acute hepatic disease
Gout is caused by the deposition of what in joints and other tissues
uric acid
what is the clinical significance of a mildly elevated ALP in a teenager?
no clinical significance
what is the normal ratio of BUN to creatinine?
10:1 - 15:1
what enzyme is normally elevated during pregnancy?
alkaline phosphatase
L-tartrate is used in the specific assay of which enzyme?
prostatic acid phosphatase
which isoenzyme is detectable within 4-6 hours after a MI?
CK-2 or CK-MB
retention of BSP can be used to measure what function?
liver
what substrate and coenzyme are required to measure ammonia?
alpha ketoglutarate
NADH
what is the main way that ammonia levels are kept within normal limits?
synthesis of urea in the liver
Amylase is an enzyme that breaks down what?
starch
why should hemolyzed specimens NOT be used for acid phosphatase?
RBC contain acid phosphatase levels increase
acid phosphatase is primarily associated with diseases of what
prostate
what is the proper treatment of serum to be assayed for ACP?
acidified to a pH below 6
what is the substrate for alkaline phosphatase methods of analysis?
para-nitrophenolphosphase
in the urease method, urea is converted to what?
ammonium carbonate
increased levels of serum alkaline phosphatase can indicate diseases of what?
bone or the liver
the enzyme responsible for the reversible oxidation of lactic acid to pyruvic acid is what?
LD
lactase dehydrogonase
in the creatine kinase reaction what is converted?
ATP to ADP
what is the end product or purine metabolism in man?
uric acid
serum amylase might be expected to be increased in diseases of the what?
pancreas and salivary glands
which enzyme can be used to establish the presence of semen?
acid phosphatase
phenylketonuria (PKU) results from a deficiency in which enzyme?
phenylalanine hydroxylase
what is the substrate for the enzyme alanine aminotransferase (ALT)
alanine
alpha-ketoglutamic acid
what is the source of urease used in enzymatic methods for the determination of BUN
jack bean meal
what precaution must be taken with specimens to be used for blood ammonia determinations?
avoid ammonia forming in vitro
placed on ice
correct tube
plasma tested within 15 minutes
what is the correct order of migration of the creatine kinase (CK) isoenzymes starting with the slowest?
CK-MM
CK-MB
CK-BB
what is(are) the substrate(s) for amylase in the dye-labeled substrate method?
starch & dye
in the creatinine method, a color develops when creatinine combines with what
alkaline picrate
the major isoenzymes of lactate dehydrogenase come from the what?
heart and liver
what is the principle of the enzymatic method for measurement of ammonia?
change in absorbance at 340 nm uses enzyme glutamate dehydrogenase and the substrate alpha-ketoglutarate & the reaction is followed by decreased absorbance @ 340 nm as NADPH is converted to NADP
strenuous exercise can cause an elevated what
CK
what causes the BSP dye to turn from colorless to colored?
alkali medium
what would hemolysis do to the results of a lactate dehydrogenase (LD) measurement?
elevates results
how are the results of LD measurement affected if the specimen is frozen?
falsely decreased
what test can differentiate between liver and bone origin of an elevated alkaline phosphatase?
GGT
what is the best anticoagulant to use for plasma specimens to be tested for LD
heparin
what is the order of migration for the isoenzymes of alkaline phosphatase
liver fastest
bone
placenta
intestinal
what is the characteristic change in the isoenzyme of LD that is seen in MI?
LD 1 is greater than LD 2
creatinine excretion correlates best with what
muscle mass
which enzyme is the first to become elevated following a MI?
CK-MB
aspartate amino transferase is elevated in diseases of what
heart
for how long and at what temperature should specimens for LD be stored
2-3 days at room temperature
in the performance of a creatinine clearance, when should the specimen for serum creatinine be collected in relation to the collection of the urine?
midway through urine collection NOT longer than 24 hours before or after collection
what enzyme can be used in the detection of alcoholism and in the monitoring of patients in alcohol treatment centers
GGT
what is the normal value for prostatic acid phosphatase
less than 2.1 ng/ml
why are creatinine levels in the serum not a good indicator of early renal damage?
values are not above the upper limit of normal until 1/2 to 2/3 of renal function is abnormal
what is the composition of Nessler’s reagent and for what test is it used?
double iodide of potassium/mercury
BUN
which has more liver specificity, alanine aminotrasnferase (ALT) or aspirate amintoranferase (AST)
ALT is more specific
AST is for the heart
in which organs is the activity of creatine kinase (CK) the greatest
brain
heart
skeletal muscle
what is the main factor that determines how much the level of an enzyme in serum increases?
extent
severity of damage to its tissues or cells of origin
how does progressive muscular dystrophy affect AST and ALT levels
increases AST and ALT levels
what is the normal value for serum amylase at 37C
95-290 IU/L
what is the major creatinine kinase isoenzyme of normal serum?
CK-MM
at what temperature should serum CK specimens be stored?
4C refrigerated
what is the purpose of the PSP test and the p-aminohippurate test
measure excretory capacity of the kidneys
to what class of enzyme do amylase and lipase belong
hydrolase
what is the normal value for serum BUN
8-26 mg/dl
what is the old name for AST
SGOT
serum glutamic oxaloacetic transaminase
what is the old name for CK
CPK
creatine phosphokinase
what two isoforms of CK are used for the early detection of an MI
CK-MM
CK-MB
what is the main use of ammonia measurements
diagnose Reye’s syndrome
hepatic coma
what happens to the creatinine clearance value in renal disease
decreases
What is the normal range for total serum bilirubin?
0.2-1.0 mg%
In the Jendrassik-Grof method, what is the caffeine benzoate solubilizer used for?
Solubilizes the water-insoluble fraction of bilirubin and will yield a total bilirubin value. Without it, the rxn will yield conjugated bilirubin only
A list of risk factors for coronary heart disease
Smoking Hypertension Increased total cholesterol & LDL Decreased HDL Diabetes mellitus Age Obesity Physical Inactivity Family history of premature CHD Left ventricular hypertrophy
List of biochemical markers for coronary heart disease
Triglycerides
Lp(a)
Homocysteine
hs-CRP
List of the ideal characteristics of a cardiac marker
Cardiac specific Rises soon after infarction occurs Elevated over a sustained period of time Easy to measure analytically Broad dynamic range for measurements Quick turnaround of tests Diagnostic utility verified by clinical studies
Which marker has been recognized for the earliest biochemical marker for AMI?
Myoglobin
What is the biggest disadvantage of troponin as a cardiac marker?
Remains in blood 7-10 days (can’t detect new infarction within that time frame)
What is the most likely cause of prehepatic bilirubin?
Increased amount of bilirubin being presented to the liver, such as in acute or chronic hemolytic anemias
Why are high levels of bilirubin seen in infants?
infant deficiency of enzyme glucuronyl transferase (last to develop because most bili processing done by mother)
What precautions need to be taken when processing bilirubin?
Serum or plasma (except in Malloy-Evelyn, use serum)
Fasting specimen preferred
Hemolysis not acceptable
Keep away from light
Stable 2 days at RT, 1 week at 4C, indefinitely at -20C
