Fasting Required: No Specimen: Blood Results: 3-5 Business Days Description: The TPO gene provides instructions for making an enzyme called thyroid peroxidase. This enzyme plays a central role in the function of the thyroid gland. Thyroid peroxidase assists the chemical reaction that adds iodine to a protein called thyroglobulin, a critical step in generating thyroid hormones. Thyroid hormones play an important role in regulating growth, brain development, and the rate of chemical reactions in the body (metabolism). Methodology: Immunoassay (IA) Reference Range(s): <9 IU/mL Clinical Significance: Assists in the diagnosis of thyroid diseases such as endemic goiter, Graves Disease, autoimmune thyroiditis, Addison's Disease, insulin-dependent diabetes mellitus, Hashimoto's Disease and polyendocrine auto-immunopathies.