Approach to abnormal liver function Flashcards
What are normal bilirubin levels?
> 80% serum unconjugated bilirubin (aka increased indirect bilirubin!)
How do you calculate indirect bilirubin?
Measure total bilirubin
Measure direct bilirubin
Indirect = total - direct
(recall indirect should account for >80% of your bilirubin)
What is the most common cause of high unconjugated bilirubin?
neonatal jaundice!
What is the most common cause of high unconjugated bilirubin in adults?
GILBERTS Disease
What is gilberts disease? and what would blood tests look like?
- AutoDom
- 5% prevalence
- defect in UDP Glucuronyltransferase (UTP) which is a liver enzyme that slaps a glucuronide onto bilirubin thus making “direct bilirubin”…
therefore with a decrease UTP activity, there can be an elevated amount of unconjugated bilirubin (UCB)
Is Gilberts a serious disease?
normally fairly benign, and patient only becomes jaundiced with stress (ie fever or surgery)… normally people don’t know they even have it
What is Crigler-Najar? What would a blood test look like?
Same thing as Gilberts, except it is an ABSENCE of UDP glucuronyltransferase! presents in infants early in life and frequently causes death within first few years
Extremely high unconjugated bilirubin
What is Dubin-Johnson Syndrome? and what would blood tests look like? What is unique about this?
It is a defect in release of conjugated bilirubin from liver into bile…
Results in elevated conjugated bilirubin (hyperbilirubinemia)
***Causes the liver to turn black!!!
What is the most common cause of conjugated hyperbilirubinemia?
cholestasis!… back-up of conjugated bilirubin in liver… so it leaks into the blood to be measured via blood test… this is the most common cause of jaundice!
You have a person w/ a history of hep. B (so could turn into a chronic condition) who is also a heavy drinker comes in jaundiced… how would AST or ALT levels point you to whether is is a viral or alcohol induced issue?
EtOH hepatitis = AST/ALT >2… remember this because you get “wASTed”
In viral hepatitis = ALT > AST
Is an elevated alkaline phosphatase specific for liver conditions?
NO… could also be due to bone growth
What blood tests would you expect to see with cholestasis?
Elevated Alk Phosph & GGT w/ a lag before you see any increase in ALT or AST because AP & GGT is anchored to cells and gets immediately released w/ damage, but ALT and AST only increase when there is significant enough damage to cause cell death at which point they leak out…
Why would Prothrombin time be a good measure of liver function?
PT is dependent on coag factors 9, 10, 7 & 2 among others… all of which are made by the liver and have short half lives… so an acute liver defect could be picked up quickly with an increase in PT…
Recall factor 8 would not tell us anything about PT… because it is not made in the liver…
What are 4 “true” liver function tests?
1) bilirubin
2) prothrombin time – makes all the factors except 8 (with short half lives)
3) albumin - synth by liver (but has a 20 day half life)
4) Ammonia - metabolized by liver, so it will be high in severe dysfunction and/or porto-systemic shunting…
In questioning for possible hep. C infection what should you ask?
1) blood transfusion before 1992
2) tattooes
3) IV drug use/sharing needles
4) possibly sex (more of a hep b thing)
