A case of Gilbert's syndrome combined with macroamylasemia

A 30-year-old Japanese male, who had no remarkable family history, visited our hospital with a complaint of abdominal pain, and unconjugated hyperbilirubinemia and hyperamylasemia were observed. He showed negative hemolysis tests, positive nicotinic acid test, low hepatic bilirubin UDP-glucuronyltransferase activity, decreased bilirubin diglucuronide and increased bilirubin monoglucuronide in bile, and a decrease in serum bilirubin after phenobarbital administration. He also showed high serum amylase level, low urine amylase level, and low amylase-creatinine clearance ratio. Gel filtration of serum with Sephadex G-200 revealed the existence of macroamylase. Countercurrent immunoelectrophoresis proved binding of serum amylase to lambda type IgA. From these results, the case was diagnosed as Gilbert's syndrome combined with macroamylasemia.