Also known as: Antimicrosomal Antibody, Antithyroid Microsomal Antibody, Thyroid Peroxidase Autoantibodies, TPO Antibodies.

Antibodies to thyroid microsomes (thyroid peroxidase) are present in 70% to 90% of patients with chronic thyroiditis. They are present in smaller percentages of patients of other thyroid diseases as well. Antibody production might be confined to lymphocytes within the thyroid, and serum might be negative. A small percentage of people with no evidence of disease may have antibody. This is more frequent in women and increases with age.