Exam 4 Flashcards
What is the substrate for the enzyme aspartate amino transferase (AST)?
aspartate and alpha ketoglutamic acid
creatinine is formed from the breakdown of what?
creatine
PSP is removed from the blood by what organ?
kidney
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, lipemia, and icteric specimens (blue endophenol compound) is formed.
what is the normal value for serum AST at 37 C?
5-35 IU/L
which anitcoagulant should NOT be used for urease testing?
sodium fluoride
what is the normal percentage for the CK-MB isoenzyme?
what reagent is used in the measurement of uric acid?
phosphotungstic acid
creatinine clearance is used to assess the rate of what?
glomerular filtration
calculation for creatinine clearance if given urine volume and values for plasma
CrCl=UcrVu
PcrT
what additional information must be known for the calculation if the pt is an 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 disease of what tissue?
muscle
serum lipase levels are elevated to diseases of what organ?
pancreas
what is uremia?
abnormal substances in the blood retention of urea in the blood
what is the principle of the Berthelot reaction and what substances can cause falsely elevated values in the reaction?
hydrolysis of urea to annonium carbonate by enzyme urease ammonia, lipemia, and icteric specimens
increased ALT values are associated with disease of what organ?
liver
what is the normal value for serum AST at 37 C?
5-35 IU/L
which anitcoagulant should NOT be used for urease testing?
sodium fluoride
Gout is caused by the deposition of _____ in joints and other tissues?
uric acid
Diacetyl monoxime reacts with what to produce yellow product?
urea
what is the normal value for CK in males at 37 C?
15-160 IU/I
name 3 ways that can not be used in the lab to measure the rate of an enzymatic reaction?
multiple point assay
kinetic
contiunous monitoring point
Define IU (international unit)
catalyzes one micromole (mmol) per min
what is the peak absorband of reduced NAD (NADH)?
340 nm
the Jaffee reaction is used to measure what?
creatinine
which non protein nitrogen component comprises the largest fraction of NPN in the blood?
urea
which enzyme is useful in the detection of insecticide poisoning?
pseudocholinesterase
low levels of which enzyme can cause a pt to be susceptible to prolonged apnea when exposed to certain types of anesthesia?
pseudocholinesterase (most clinically significant)
increased levels of LD-4 and LD-5 are associated with what?
liver/acute hepatic disease
what is the clinical significance of a mildly elevated ALP in a teenager?
they are still growing so there is no significance
what is the normal ratio of BUN to creatine?
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 with-in 4-6 hrs after a MI?
CK-2 or CK-MB
what precaution must be taken with specimens to be used for blood ammonia determinations?
avoid ammonia forming in vitro (outside the body)
what substrate and coenzyme are required to measure ammonia?
alpha-ketoglutarate
NADH is coenzyme
what is the main way that ammonia levels are kept within normal limits?
liver takes ammonia and makes urea
amylase is an enzyme that breaks down what?
starch and glycogen
why should hemolyzed specimens NOT be used for acid phophatase?
RBC contain acid phophatase and it could cause an increase in levels
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 for analysis?
para-nitrophenolphosphase
in the urease method urea is converted to what?
ammonium carbonate
increased levels of serum alkaline phophatase can indicate disease of what?
bone and liver
the enzyme responsible for the reversible oxidation of lactic acid to pyruvic acid is what?
LD
in the creatine kinase reaction ___ is converted to ______.
ATP to ADP
what is the endpoint of purine metabolism in man?
uric acid
serum amylase might be expected to be increased in diseases of the ______
pancreas
which enzyme can be used to establish the resence of semen?
acid phophatase
phynylketonuria (PKU) results from a deficiency in which enzyme?
phenylalanine hydroxylase
what is the substrate for the enzyme alanine aminotransferase (ALT)?
alanine and 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 (outside the body)
kept closed
on ice
what is the correct order of migration of the creatine kinase (CK) isoenzymes starting with the slowest?
CK-MM (muscle)
CK-MB
CK-BB (brain)
what are the substrates for amylase in the dye-labeled substrate method?
starch and dye
in the creatinine method, a color develops when creatinine combines with what?
alkaline picrate
the major isoenzymes of lactate dehydrogenase comes from the ______ and the ______.
heart
liver
what is the principle of the enyzmatic method for measurement of ammonia?
uses enzyme glutamate dehydrogenase and the substrate alpha ketogluturate reaction followed by decrease in absorbance at 340 nm as NADPH is converted to NADP
streunous exercise can cause and elevate what?
CK
what causes the BSP dye to turn from colorless to colored?
alkaline medium
what would hemolysis do to the results of a lactate dehydrogenase (LD) measurement?
elevated results
what would the results of a lactate dehydrogenase if frozen?
falsely decreased
what test can differentiate between liver and bone origin of an elevated alkaline phosphatatse?
GGT
what is the order of migration for the isoenzymes of alkaline phohatase (ALP)?
liver fastest, bone, placenta, intestinal
what is the best anticoagulant to use for plasma specimens to be tested for lactate dehydrogenase?
heparin
what is the characteristic change in the isoenzyme of lactate dehydrogenase (LD) that is seen in a myocardial infarction (MI)?
1 is greater than 2 in LD
2 is greater than 1 in MI
creatinine excretion correaltes best with the _______
muscle mass
which enzyme is the first to become elevated following a MI?
CK
aspartate aminotransferase (AST) is elevated in diseases of the ______
heart
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 thru urine collection and no longer than 24 hrs before or after collection
what enzyme can be used in the detection of alcholism and in the monitoring of patients in alcohol treatment centers?
GGT
what is the normal value for prostatic acid phosphatase (ACP)?
why are creatinine levels in the serum not a good indicatior of early renal damage?
values are not above normal until 1/2-3/4 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 aminotrasferase (ALT) or aspartate aminoransferase (AST)
ALT is more specific
AST for heart
in which organs is the activity of creatine kinase (CK) the greatest?
brain heart and skeletal muscle
what is the main factor that determines how much the level of an enzyme in serum increases?
severity of damage to its tissues and cells of origin
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
how does progressive muscular dystrophy affect AST and ALT levels?
increases both AST and ALT levels
what is the normal value for serum amylase at 37 degrees
95-290 IU/L
what is the major creatine kinase (CK) isoenzyme of normal serum?
CK-MM
at what temp should serum specimens be stored?
4 degrees C refrigerated
what is the purpose of the PSP test and the p-aminohippurate test?
measure excretory capacity of the kidneys
to what class of enzymes 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
what is the old name for CK?
CPK
what two isoforms of CK are used for the early detection of MI?
CK-MM
CK-MB
what is the main use of ammonia measurements?
diagnose reyes syndrome, diagnose pending or existing hepatic comma
what happens to the creatinine clearance value in renal disease?
decreases
risk factors for CHD
smoking
obesity
which marker is recognized as the earlist chemical marker of an AMI?
myoglobin
Total bilirubin, unconjugated bilirubin, conjugated values
0.2-1.0 mg/dl
biochemical markers for CHD
triglycerides
homocysteine
high sensitivity CRP
LPA
what makes an ideal 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
what is the biggest diadvantage of the troponin cardiac marker?
remains in blood 7-10 days (can not detect new infarction within that time frame)
causes of prehepatic, hepatic and post hepatic bilirubin
increased amount of bilirubin being presented to the liver, such as in acute of chronic hemolytic anemias
why are high levels of bilirubin seen in newborns?
they lack of enzyme that processes bilirubin
what precautions should be taken with bilirubin speic
- serum or plasma
- fasting sample
- hemolysis not acceptable
- keep away from light
- stable 2 days at RT, 1 week at 4 C, indefinietely at -20C
