Smooth Muscle Antibodies

Smooth muscle antibodies (SMA) are autoantibodies that target proteins in smooth muscle cells, which are found in many organs including blood vessels and the digestive tract. These antibodies are primarily associated with autoimmune hepatitis type 1, the most common form of autoimmune hepatitis, where the immune system attacks liver cells. SMA can also be found at low levels in other autoimmune conditions and sometimes in healthy individuals. Testing for smooth muscle antibodies, usually alongside other autoimmune markers, helps diagnose autoimmune hepatitis and guide treatment decisions to prevent liver damage.