Chemistry Board Review

fasting hypoglycemia is defined as:

< or equal to 55mg/dL (< or equal to 3.0 mmol/L)

fasting hyperglycemia is defined as:

126 mg/dL (7 mmol/L) or higher

glucose levels in: serum:

72-99 fasting

glucose levels in whole blood:

70-130 mg/dL

glucose levels in CSF:

45-80 mg/dL (60% [ ] of blood)

glucose levels post-prandial:

how to prep for GTT

glucose tolerance test: high carb diet for 3 days, if vomit, stop

CSF for glucose should be:

Analyzed immediatley

when fasting, venous glucose should be ______ higher than capillary and arterial.

5 mg/dL (0.27 mmol/L)

fructosamine test measures :

past 2-3 weeks (glucose)

A1C measures over:

2-3 months

hemolytic anemia will show ______ glycated Hgb b/c directly related to life of RBC

lower

ion-exchange chromatographic methods falsely ____ Hgb A1C due to _____

increased,HgbS

acetone is a product in:

Carb metabolism. if you have an increase in acetone it means you have a carb metab defect.

Benedict's copper reduction test:

detects glucose in urine. subs that reduce copper sulfate to cuprous oxide in prescence of alkali and heat will produce color change confirming - a reducing substances (not specific for glucose)

Glycolysis _____ in a centrifuge

stops

what is elevated post exercise:

lactic acid, elevated pyruvate

how to diagnose lactase def:

H2 breath test

true glucose [ ] in whole blood is fxn of:

HCT: H2O content much higher in plasma than whole blood so ratio of cells/plasma effects glucose resutls

HCT:

volume of RBCs to all other contents in blood

what does sodium fluoride do:

inhibits glycolysis by preventing WBCs consuming (works for short time, not more than hour)

IU of enzyme activity:

1 umol/min

in spectrophotometry, formula for absorbance of sol:

absorbtivity x light path x [ ]

most specific method for glucose in all body fluids uses:

hexokinase which is specific for other isomers of glucose. it measures amount of NADH from reduced NAD

example of glucose-specific colorimetric method?

glucose oxidase

what catalyzes splitting of fructose 1,6 - diphosphate to glyceraldehyde-3-phosphate and dihydroacetone phosphate

aldolase

consistent analytical error with determination of HDL-cholesterol is caused by:

small [ ] of apo B-containing lipoproteins after precipitation.

HDL composed of:

20%lipid, 50%protein

tri 5%, chol 15%, protein 50%

transportation of 60-75% of plasma choesterol is performed by:

LDL

what disease results from familial absence of HDL?

Tangier disease. defect in catabolism of Apo A-1, an essential apoportein for HDL. due to increased HDL catabolism.

if you put lipid profile in fridge over night 4.C what will you see in the morning: hyperlipoproteinemia and lipoprotein lipase def

creamy layer over clear serum. chylomicrons are present as thick layer on top over plasma surface which typifies familial hyperchylomicronemia due to def in lipoprotein lipase activity.

which lipid result woul dbe expected to be falsely elevated on a serum specimen from a non-fasting patient?

triglycerides.

inhertited disease in which near total def of enzy N-acetyl-beta-dexosaminidase A

Tay Sachs this enzy responsible for hydrolysis of the Beta (1,4)- glycosidic bond between N-acetyl galactosamine and galactose in GM2 gangliosidic. Results in excess phospholipid GM2-gagliosie in neurons.

which dyslipidemias are chylomicrons present?

def of lipase. which hydrolyses chylomicrons and triglycerides.

function of VLDL

endogenous triglyceride transport. in endog path, liver makes trigs from carbs and fatty acids. packed in VLDL and takes to circulation.

turbid serum/ or plasma suggests

elevated chylomicrons

lipemic spec separated and frozen at 120C, to test, week later what should done to test again

warmed @ room temp (37C) and mixed.

fast how long for triglyceride spec test?

10-14 hours but shouldn't be

formula for calculation of absorbance with % T of sol?

2 - log (%T)

sub used to estimate serum [ ] of triglycerides by most methods:

glycerol

method for quant of HDL most suited for clinical labs?

uses antibodies or complex agents to mask or consume nonHDL so no seperation req

A1C

glycosylation of valine in polypeptide N-terminus of adult Hgb

prinicple of occult blood test depends on

peroxidase activity of Hgb

Hgb S can be sep from D by

electrophoresis on diff medium (citrate agar gel) and acidic pH (5.9)

electrophoresis @ alkaline pH, which Hgb slowest?

C

fastest Hgb on electrophoresis at alkaline pH

A

Hgb resistant to alkaline denaturation

Hgb F

urobilinogen formed in

intestines

purpose of adding caffine or methyl alcohol in bilirubin determination is:

allow indirect bili to react with color reagent. principle of diazo rxn with conj bili

priniciple of tablet test for bili in urine/feces

chemical coupling of bili with a diazonium salt to form a purple color

plasma hepranized sample for bili ran by Jendrassik-Grof metho and Evelyn-Mallow. 10-20% higher for 2nd , why?

alcohol reagents cause precipitation of proteins and increased background turbidity.

in liver, bilirubin is converted to:

bilirubin diglucuronide

increased conjugated bili major serum component in?

biliary obstruction in adults and intrahepatic biliary atresia in newborns

Crigler-Najjar syndrome

abnormal metabolism of bili due to absence or def in UDP-glucuronyltransferase resulting in increased unconj bili and kernictreus in neonates.

ref ranges for total serum bili and conj

total: 0 - 1.0 mg/dL (0-17.1 umol/L)

conj (direct) : < 0.3

increased AST but almost normal ALK

acute hepatitis

what gives feces its normal color?

urobilin

condition in which erythrocyte protoporhyrin is increased:

iron def anemia

detection of hereditary coproporphyria should include analyse of:

fresh morning urine and delta-amino levulinic acid.

disease is def of ALA syn which catalyzes 1st step of porphyrin synthesis

urine sample for 'porphyrins' includes?

porphyrin and porphobilinogen screen

enz of heme bioisyn inhibited by lead?

porphobilinogen synthase. PBG synthase and ferrochelatase inihibited.

in amniotic fluid, what is used to detect HDNF

absorbance @ 450nm to detect bili

creatinine measured in amniotic fluid to:

rule out urine contamination

most widely used methods of bili measurement based on:

Jendrassik-Grof

in malloy evelyn for bili, reagent reacted with bili to form purple azobilirubin

diazotized sulfanilic acid.

in Jendrossik Groff the green color measured is:

azobilirubin

in Jendrassik_groff, total bili, alkalin tartrate added to;

raise pH to convert azobilirubin from 450- 560 nm. redish-purple chromagen, with similar absorbance as Hgb as other interfering substances to bluish fchromagen with absorbance @ 600nm.

in aminotic fluid, detection of Rh isosensitization is:

measurement @ 450nm "optical density delta 450" is use to detrmine graphical calculation of amt bili in amniotic fluid. max bili in amniotic fluid m=. max bili absorption is 450nm its found in vivo hemolysis like Rh isosensitiation.

conj hyperbili w increased ALKP assocated with?

cholestatic-hepatic biliary obstruction. if ALK is more increased than AST

most specific enz test for acute pancreatitis

lipase. both lipase and amalse used but lipase perisists longer

enz for conversion of starch to glucose and maltase

amazlye (AMS)

results fro acute pancreatisis

increase AMS and LPS but AMS normal in 3 days

AST increased in what diseases

liver ( present in liver, skeletal muscle, and cardiac tissue)

AST catalyzes:

exchange of amine and keto groups b/w alpha-amino and alpha keto acids

ASt and ALT both elevated in?

viral hepatitis.

interference in serum ezy analysis can occur when significant amount of ______ is found in RBCs

AST b/c found in many cells so when hemolysis occurs lots found.

malate dehydrogenase in coupled rxn with AST

oxidizes oxaloacetate to malate in indicator rxn.

AST and ALT can be 100x increase in:

hepatoceullar disorders

mildly increased enzys (AST, etc) can be seen in ;

chronic hepatitis, hemangioma, , obstructive jaundice.

large levels of LD are seen in

pernicious anemia, also seen in renal disease but not as much

enzy in skeletal muscle, heart, brain and high in muscluar distrophy and myocardial infarction

CK creatine kinase.

enzy present in almost all tissues and can be separated by electrophoresis into 5 isoenzymes.

LD

falsely eleveated LD seen in:

hemolyss B/c rbcs have a lot of LD1 and LD2

which isoenzy indicated acute myocardial damage?

CKMB (CK1)

elevated LD4 and LD5 seen in :

liver and skeletal muscle disease.

which enz is increased 1st in Myo infarct

CK (4-6 hours after) peaks at 12-24. and returns to normal in 48 to 72

LD is 12-24 hours after

2 peaks of CK seen with CKMB and CKMM what happend?

myocardial infarction

total increased serum LD activity is specific to:

sensitive but not specific for neoplastic disease

skeletal muscle disease would show increase in?

aldose and CK

in immunoinhibition phase of CKMB procedure what is inactivated?

M subunit

increase in LD1 and LD2 are seen in

hemolytic anemia due to hemolysis

increase in CK and ASt seen in

muscle damage (such as car accident)

increase in GGT and ALP

obstructive jaundice

if ALP asparate aminotransferase, alanine aminotransferase AST, and GGT slightly increased could mean:

chronic hepatitis but can vary

regan isoenzyme:

abnormal ALP isoenzy. carcinoplacental. originates in placenta and seen in lung breast, colon and ovarian cancer. m ost heat stable isoenz.

most heat labile fraction of ALP is from:

bone

most sensitive indicator for liver damage due to ethanol

GGT

holoenzyme

protein portion of enzyme complex

helps determine the presence of seminal fluid

acid phosphatase

Henderson-Hasselbalch eq:

pH = pKa + log [salt]/[acid]