Plasma amino acid analysis in the differential diagnosis of jaundice.

Distinguishing between obstructive (surgical) and hepatocellular (medical) jaundice is sometimes impossible using the relatively simple diagnostic means of history, physical examination and liver function tests. In an attempt to reduce the number of jaundiced patients in need of complex and expensive diagnostic procedures, we investigated the use of the plasma amino acid pattern in the diagnosis of jaundice. Jaundiced rats with galactosamine-induced hepatitis and seven patients with acute onset hepatitis presented a plasma amino acid pattern in which most all amino acid levels were elevated except for arginine in the rat and branched chain amino acids in the patients. Rats jaundiced due to common bile duct ligation and seven patients with obstructive jaundice proved at surgery exhibited a near-normal amino acid pattern. These experimental and clinical data demonstrate very clear qualitative and quantitative differences in plasma amino acid patterns of hepatocellular and obstructive jaundice, with the latter exhibiting an almost-normal pattern. We suggest the use of the plasma amino acid pattern as a useful adjunct in the differential diagnosis of medical and surgical jaundice.