Anti Mitochondrial Antibody (ELISA)

Function

The Anti-Mitochondrial Antibody (AMA) test is a serological marker primarily used to detect autoantibodies directed against the E2 subunit of the pyruvate dehydrogenase complex located on the inner mitochondrial membrane. In healthy individuals, the immune system distinguishes between self and non-self; however, in certain autoimmune conditions, the body produces AMA, which specifically targets highly metabolic cells, particularly those in the bile ducts of the liver.

Why it is Ordered

Physicians order this test when a patient presents with unexplained signs of liver dysfunction, such as elevated alkaline phosphatase (ALP) levels, jaundice, fatigue, or pruritus (intense itching). It is the hallmark diagnostic tool for Primary Biliary Cholangitis (PBC), an autoimmune disease where the small bile ducts in the liver become inflamed and eventually destroyed, leading to cholestasis and potential cirrhosis.

Associated Conditions

• Primary Biliary Cholangitis (PBC): AMA is present in approximately 90-95% of patients with PBC.
• Autoimmune Hepatitis: Occasionally seen in 'overlap syndromes'.
• Systemic Sclerosis: Some variants of scleroderma may show low-level AMA positivity.
• Idiopathic Liver Cirrhosis: In cases where the underlying cause of scarring is initially unknown.

While highly specific for PBC, a positive result must be correlated with liver function tests and sometimes a liver biopsy to determine the stage of the disease.