Lab Values Flashcards
Contrast liver tests that measure liver injury v. liver dysfunction.
injury: AST/ALT; ALKP/GGT (biliary damage)
dysfunction: bilirubin, PT/INR, albumin
Contrast ALT and AST.
ALT elevation is more specific for liver damage (greater proportion present in liver), it is only present in the cytosol, AST is presentHow in mitochondria and cytosol
How can the AST/ALT ratio be used diagnostically?
ratio 2 fairly specific for alcoholic hepatitis (due to pyridoxine deficiency, ALT is B6 dependent)
often AST/ALT >1 in cirrhosis
How is GGT used to interpret ALKP levels?
GGT is absent in bone, it is useful in distinguishing liver from bone source of elevated ALKP
both are strongly suggestive of biliary tree dysfunction (also high in infiltrative disorders, medications, alcohol)
How is urobilinogen or urobilin produced?
bilirubin in bile is hydrolyzed by bacterial B-glucuronidases
What is the cytosol carrier of bilirubin in the hepatocyte?
GST transports bilirubin to ER to be conjugated by UGT
What step(s) in the bile production pathway must be blocked in order to have bilirubin in the urine?
(must be conjugated bilirubin- soluble)
due to reduced efficiency of bilirubin excretion into bile or cholestatic disease, hemolysis
Enterohepatic circulation includes which substance?
bile lipids
When treatment with Vit K helpful in improving which haptic disfunction?
only vaguely helpful in setting of cholestasis where vitamin K absorption is reduced due to reduction in bile
hepatocyte is principle site of synthesis of all coagulation factors except vWF and VIII (hepatocyte dysfunction cannot be remedied with vit K), VII half-life is 3-6hrs
Low albumin is a sign of ___ liver disease.
chronic, it is also a negative acute phase reactant (falsely low in acute reaction)
What is the liver’s role in normal ammonia handling?
liver converts ammonia from the gut into urea and glutamine (important for detoxification because it can lead to cerebral edema)
levels increase with liver dysfunction and portal-systemic shunting
