Anti-TPO antibodies
What it measures, and what changes the number.
Anti-TPO antibodies are antibodies directed against thyroid peroxidase, an enzyme the thyroid uses to make its hormones. The test measures how much of these autoantibodies is present in serum. Older methods detected them as antimicrosomal antibodies, which is why some reports still use that name.
The test is usually read with TSH and Free T4 to show how the thyroid is functioning, and often with anti-thyroglobulin antibodies, another thyroid autoantibody.
No fasting or particular time of day is needed. Results depend heavily on the assay, and different kits use different units and cut offs, so values from different labs or methods cannot be compared directly. Labs may print it as Ac. anti Peroxidasa (TPO)/Microsomales.
Often read alongside: TSH, Free T4, Free T3, Anti-thyroglobulin antibodies