- Positive anti-mitochondrial antibodies (AMA) are the hallmark serological finding in primary biliary cholangitis (PBC), present in over 90% of cases and providing a highly specific diagnostic marker.
- AMA targets components of the mitochondrial inner membrane, reflecting autoimmune destruction of small intrahepatic bile ducts.
- While elevated alkaline phosphatase indicates cholestasis and anti-nuclear antibodies (ANA) can be seen, these are less specific.
- Liver biopsy can support diagnosis but is not definitive without AMA positivity.

Thus, AMA serology offers the most specific confirmation of PBC among available tests.

Reference: Davidson’s Principles and Practice of Medicine, 24th Edition, Chapter: Diseases of the Liver and Biliary System, Page 684.