Thyroid Function Tests

Programs that conduct any of a variety of tests for evidence of increased or decreased thyroid function including clinical physical examinations, x-ray scans of the thyroid following an injection or an oral dose of a radioisotope substance, thyroid uptake tests which measure the rate of absorption of radioactive iodine or other radionuclides per unit of time, and a variety of lab tests, some of which are based on the direct or indirect determination of the two thyroid hormones, triiodothyronine and tetraiodothyronine.