Preferred Specimen(s) 1.0 mL Serum
Transport Container Plastic screw cap vial
Transport Temperature Refrigerated 2 days
Reject Criteria Grossly hemolyzed specimen
Methodology Chemiluminescence
Clinical Significance Thyroid peroxidase (TPO) is an enzyme that catalyzes the iodination and coupling steps in thyroid hormone biosynthesis. It is now known to be the principal microsomal antigen against which antibodies are directed in autoimmune thyroid diseases. The main use of this test is to confirm that a patient diffuse goiter and/or hypothyroidism is due to autoimmune thyroiditis. The test may also help distinguish Graves’s disease from toxic nodular goiter. The TPO antibody measurement has replaced the thyroid antimicrosomal antibody (AMA) measurement. TPO antibodies may be detected in individuals without clinically significant thyroid disease. They do not define the patient’s thyroid functional status.