Articles on Medical Diseases and Conditions

Entries Tagged ‘Thyroid Tests’

Thyroid Function Tests: Free thyroxine index

The American Thyroid Association has recommended that the entity most commonly known as the free thyroxine index (TI, or T-7, T-12, Clark and Horn index) be renamed the free T4 index (FT4I). The FT4I was developed to correct the T4 assay for effects of thyroxine-binding protein alterations. It consists basically of the serum T4 result […]

Thyroid Function Tests: Total serum thyroxine

T4 can be measured directly by radioassay (or, more recently, by enzyme-linked assay). Radioassay involves competition of patient hormone and radioactive hormone for a hormone binder. In T4by radioimmunoassay (T4-RIA) the binder is anti-T4antibody; in T4 competitive binding (T4-CPB) or T4 displacement methods (T4-D) the binder is T4-binding serum protein. After patient T4 and radioactive […]

Thyroid Function Tests: Thyroid hormone-binding ratio (THBR; T3 uptake)

The THBR is a variant of what is commonly known as the T3 uptake, or T3U. T3U does not measure T3, as its name might imply, but instead estimates the amount of non occupier (unsaturated) thyroid hormone-binding sites on serum protein. Therefore, the American Thyroid Association has recommended that the name thyroid hormone-binding ratio replace […]

Thyroid Function Tests: Radioactive iodine uptake

Radioactive iodine uptake is an indirect estimate of thyroid hormone production based on the need of the thyroid for iodine to make thyroid hormone, which, in turn, depends on the rate of thyroid hormone synthesis. A small dose of radioactive iodine is given, and a radiation detector measures the amount present in the gland at […]

Thyroid Function Tests

The classic picture of hyperthyroidism or hypothyroidism is frequently not complete and may be totally absent. There may be only one noticeable symptom or sign, and even that may be vague or misleading or suggestive of some other disease. The physician must turn to the laboratory to confirm or exclude the diagnosis. There is a […]