lab medicine 2

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how do liver enzymes tell you whether liver dysfunction is due to cell necrosis or obstruction?: obstruction - increased ap, increased direct bilirubin, increased ggt

necrosis (hepatitis or something) - increased ast and alt

enzymes being induced vs enzymes leaking from dead cells
what are some biliary obstruciton markers?: alkaline phosphatase - production increased in response to extrahepatic obstruction of the biliary tree

bilirubin

ggt (synthesis is increased by cholestasis, alcohol, and drugs like phenobarbitol)
difference b/t direct and indirect bilirubin?: conjugated bilirubin can be measured directly

unconjugated bilirubin is measured indirectly
what do high levels of indirect bilirubin indicate?: hemolytic disease
what increases ggt?: cholestasis
alcohol
drugs (phenobarbitol)
what kind of increase in ap would an extrahepatic vs intrahepatic block cause?: intrahepatic - 2-3 fold increase
extrahepatic - >3 and up to 10-11 fold worse, a greater increase!
what do incresed alt and ast tell you about the liver?: cell necrosis
how can you tell where elevated AP came from?: liver lives, bone burns

liver is heat resistant isoform

now you can do electrophoresis
what does albumin tell you about liver disease?: acute - increased albumin
chronic - decreased albumin
how would you differentiate b/t obstructive and hepatocellular liver disease just using AST and AP: AST > 3x
AP < 2x
hepatocellular

AST <3x
AP >2x
obstructive
4 Fs predisposing to gallstones: fat female fertile forty
what is wilson's disease?: copper overload
which is worse, hepatitis A or B: B is much worse

A always resolves in 6 weeks
B can be acute and self limiting, resolving in 6 months. it can also become chronic
how is hepatitis b usually diagnosed: HepB surpresence of these denotes recoveryface Ag
what test can tell you if you are going to recover from hepatitis B?: IgG to the surface antigen (vs IgM)
how does HepB kill you?: all the liver functions get screwed up

gluconeogenesisis
plasma protein synthesis
are AST, ALT, and LDH sensitive or specific markers for hepatocellular liver disease?: they are sensitive but not specific. good for screening. catch true positives but also give false positives
what 2 antibodies do a sandwich assay use?: capture antibody and detection antibody
how can albumin be used to follow progression of nephropathy: micro albumin in urine
when would you measure glycosylated albumin?: in a diabetic patient with an unstable form of hemoglobin where glycosylated hemoglobin cannot be measured
formula and use for sensitivity: sensitivity is used to rule out

sens = TP / (TP + FN)
formula and use for specificity: specificity is used to rule in

spec = TN / (TN + FP)
fasting glucose level for DM: 126
OGTT level for DM: 200
why does someone in DKA have hyponatremia?: sodium goes down 1.6 mmol/L for every 100 glucose because it is diluted by the increased plasma volume
why does someone in DKA have hyperkalemia?: acid exchanges for K
does someone in DKA have high or low intracellular potassium?: low because H+ exchanges for it!
what is Cl level of someone in DKA?: HCO3 is decreased
Cl is decreased too because it shifts into cells in exchange for HCO3 (AE)
why is BUN elevated in DM type I?: they are breaking down protein!
what is osmolar gap?: difference between measured and calculated osmolyte level
measured - (2NA + urea + glucose)
greater than 10 is abnormal
what can elevate osmolar gap: acetoacetate, acetate, and BHBA
ethanol
greater than 10 is abnormal
what is anion gap: diff b/t levels of major anions and cations.

indicates presence of mystery anions
such as ketones
difference b/t isoenzymes and isoforms?: isozymes are from different loci

isoforms are with different post trans mods
3 types of CK?: CK MM
CK MB - heart isoenzyme
CK BB
where is CK MB: heart
where is CK MM: muscle
what is CKMB/CK: a ratio which is better to use because there is some CKMB in muscle
what is the cutoff point for normal CKMB/CK: 2.5%
what is CKM+B+ CKM+B- CKM-B+ and CKM-B-: + and - are isoforms. - has an amino acid cleaved.
what is a macro enzyme?: enzymes aggregated to circulating IGs. this keeps them from being cleared and they elevated measured nzm levels (false psitives)
what can increase myoglobin: skel muscle injury (even minor - lifting weights)
MI
renal failure
is troponin I elevated by renal failure?: NO
how many hours after a heart attack will troponin I be detectable?: 8-48 hours after
elevated up to a week or so
which LDH isozyme is concentrated in the heart?: LDH-1
what is the temporal change for CKMB like? vs troponin I: up and down in 48 hours
troponin stays high for about a week
when should you order cardiac markers: on admission
2-4 hours
6-9 hours (troponin should be elevated by now even if not at admission!!!)
wTf are heterophile antibodies?: they bind to all sorts of animal antibodies and can form a bridge in a sandwich assay between the detection and the capture antibody!!!

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