Tests of hepatic function

• Albumin: marker for liver protein synthesis, can help differentiate acute vs. chronic liver failure, may be normal in acute hepatocellular injury (t1/2 ~15–18 d)

• Prothrombin time (PT): depends on synthesis of coag factors by liver (except FVIII); b/c t1/2 of some factors (eg, V, VII) is short, ↑ PT can occur w/in hrs of liver dysfxn

• R-value = ratio of ALT:Aϕ normalized to ULN for each = (ALT/ULN) ÷ (Aϕ/ULN)

R >5 suggests hepatocellular injury, <2 suggests cholestatic injury, 2–5 suggests mixed