Bottom line: Antimitochondrial antibodies (AMA) have a high sensitivity and specificity for diagnosing primary biliary cirrhosis.
Details: Primary Biliary Cirrhosis (PBC) entry in DynaMed Plus
Reports sensitivity 90%-95% and specificity more than 99%
References Lindor KD, Gershwin ME, Poupon R, Kaplan M, Bergasa NV, Heathcote EJ, American Association for Study of Liver Diseases. Primary biliary cirrhosis. Hepatology. 2009 Jul;50(1):291-308.
Lindor cites study reporting that AMA is present in 90-95% of patients with PBC and less than 1% of normal controls. Another study reported “fewer than 5% of patients with PBC are AMA-negative.”