This document addresses laboratory testing of thyroid function. Thyroid function tests include serum testing for thyroid stimulating hormone (TSH) and levels of specific thyroid hormones; including total and free thyroxine, thyroid hormone (T3 or T4) uptake, and thyroid hormone binding ratio (THBR). Thyroid gland hormones regulate the metabolic rate, affecting all body functions.

Clinical Indications

Medically Necessary:

Thyroid function testing is considered medically necessary for individuals who meet any of the following indications:

• For evaluation of signs or symptoms consistent with thyroid disease; or
• To evaluate, assess, or monitor confirmed or suspected thyroid disease; or
• To evaluate thyroid function when there are risk factors for thyroid disease.

Not Medically Necessary:

The use of thyroid function tests are considered not medically necessary when the criteria listed above are not met, including as a screening test in the absence of risk factors.