Thyroid Peroxidase (TPO) Antibodies

This test is used for differential diagnosis of hypothyroidism and thyroiditis.

This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.

This test should be used in conjunction with an antithyroglobulin test, since autoimmune thyroiditis may demonstrate a response to antigens other than thyroid microsomes. To order both antithyroglobulin and antimicrosomal tests, use Test No. 006684. Other autoimmune disorders such as Sjögren's syndrome, lupus erythematosus, rheumatoid arthritis, pernicious anemia and others may be positive for antimicrosomal and antithyroglobulin. Patients with myxedema, granulomatous thyroiditis, nontoxic nodular goiter and thyroid carcinoma may occasionally produce thyroid antibodies.

Electrochemiluminescence immunoassay (ECLIA)

This assay is performed on the Roche cobas instrument in multiple laboratories throughout Labcorp.

Antibodies to thyroid microsomes (thyroid peroxidase) are present in 70% to 90% of patients with chronic thyroiditis. They are also present in smaller percentages of patients of other thyroid diseases. Antibody production may be confined to lymphocytes within the thyroid, and serum may be negative. Small numbers (3%) of people with no evidence of disease may have antibody. This is more frequent in females and increases with age.