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 […]
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 […]
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 […]
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 […]
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 […]
Many persons have at least one sign or symptom that could suggest thyroid disease. Unfortunately, most of these signs and symptoms are not specific for thyroid dysfunction. Enumeration of the classic signs and symptoms of thyroid disease is the best way to emphasize these facts. Hyperthyroidism Thyrotoxicosis from excess secretion of thyroid hormone is usually […]
Thyroid hormone production and utilization involve several steps (Fig. 29-1). Thyroid gland activity is under the control of thyroid-stimulating hormone (TSH, space or thyrotropin), produced by the anterior pituitary. Pituitary TSH secretion is regulated by space thyrotropin-releasing hormone (TRH, thyroliberin, protirelin) from the hypothalamus. The main space raw material of thyroid hormone is inorganic iodide […]
