The predictive value of antimitochondrial antibodies in establishing the diagnosis of primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) was diagnosed in 85% of patients with antimitochondrial antibodies (AMA) found in sera routinely analyzed for autoantibodies. In these patients and in those without PBC other autoimmune disorders were common, but the latter patients generally had a low AMA titer, 1:80 or less. It was concluded that a low AMA titer may occur in many patients without PBC. On the other hand, it appears very likely that PBC is present in patients with an AMA titer exceeding 1:80 and an increased activity of alkaline phosphatases without signs of extrahepatic biliary obstruction.