Bilirubin in Biliary Obstruction
1.Causes: Stone in the common bile duct; carcinoma in the head of the pancreas.
2.Initially causes an increase in conjugated bilirubin.
3.Later, unconjugated bilirubin increases, with stabilization of the ratio at about 1:1 conjugated:unconjugated
1.Causes: Multiple (hepatitis, drug/alcohol injury, active cirrhosis, congestion, metastatic tumor).
2.Variable increase in both conjugated and unconjugated bilirubin, so ratio differs between patients.
A relative increase in conjugated bilirubin tends to suggest some type of obstruction; a relative increase in unconjugated bilirubin tends to suggest increased bilirubin production or (less commonly) hepatocellular disease.