Serum alpha-fetoprotein levels in extrahepatic biliary atresia, idiopathic neonatal hepatitis and alpha-1-antitrypsin deficiency (PiZ).

Serum alpha-fetoprotein levels were measured using a sensitive radioimmunoassay in 77 infants presenting with persistent conjugated hyperbilirubinaemia. A breed range of alpha-fetoprotein concentrations occurred in both the 23 infants with extrahepatic biliary atresia and the 35 with idiopathic neonatal hepatitis but the 13 with alpha-1-antitrypsin deficiency had uniformly low levels. High alpha-fetoprotein concentrations (above 10 000 mug/1) favoured the diagnosis of neonatal hepatitis especially in the first ten weeks of life, but the overlap between neonatal hepatitis and extrahepatic biliary atresia was large and alpha-fetoprotein determination cannot be recommended as a reliable method for distinguishing the two conditions. Serial alpha-fetoprotein values showed no consistent relationship with standard liver function tests and gave no guide to prognosis. There was an association between alpha-fetoprotein production and needle biopsy evidence of hepatic giant cell transformation. The uniformly low alpha-fetoprotein levels in alpha-1-antitrypsin deficient infants with neonatal hepatitis is a new observation and possible mechanisms for disordered glycoprotein release are discussed.