A radioimmunoassay procedure for thyroxine (14) is described, for which only 25 il of serum is required. The antibody, commercially available, is produced in rabbits in response to injections of a T4-albumin conjugate. Native T4-binding proteins are denatured by heating 25 .tl of serum in 0.2 ml of a glutamate buffer in a boiling water bath. After a 1-h incubation of heat-treated serum with l12...

THYROID PHYSIOLOGY The thyroid gland lies inferior to the thyroid cartilage and is composed of 2 lobes that lie on either side of the trachea (Figure 1). The lobes are joined by a small band of tissue called the isthmus. Normally not visible on inspection, the thyroid gland can be palpated during swallowing when it is upwardly displaced. Thyroid tissue is highly vascular and is composed of foll...

Endogenously radioiodinated thyroglobulin (tg) and thyroxine (T4), in the circulation following, therapeutic doses of radioiodine were studied in five patients with differentiated thyroid carcinoma. Radioactive serum was fractionated on a Sephadex G-200 and the various radioactive peaks thus obtained were analyzed for their biochemical and immunologic characteristics using precipitation with tr...

The purpose of the study was to observe changes in the skeletal system of rats with subclinical hypothyroidism (SCH) and to determine whether L-thyroxine (L-T4) administration suppresses those changes. Sixty male Wistar rats were randomly divided into control, SCH, and SCH+T4 groups. SCH was induced in rats by administration of methimazole (MMI), and rats in the SCH+T4 group were treated with L...

Thyroid hormones physiologically regulate the semen quality, by altering testosterone concentrations, and different seminal parameters, as well sperm motility, viability volume. Serum thyroxine (T4), free (fT4), thyroid-stimulating hormone (TSH) (T) concentrations were measured in 26 adult Labrador Retriever dogs (n. 20 normospermic n. 6 azoospermic groups), aged 3 ± 0.5 years old, to determine...

background: to investigate thyroid function in preeclamptic patients in comparison with normal pregnant women. methods: in this analytical cross-sectional study free thyroxine (t4), and thyroid stimulating hormone (tsh) levels were measured in 100 preeclamptic patients and were compared with free t4 and tsh levels in 101 normal pregnant women in their third trimester of pregnancy. patients with...

There are many alternative ways of estimating free thyroxine (T4) when thyrotropin screening results are abnormal. In addition to free T4 immunoassays, the menu of most automated immunoassay instruments includes a nonisotopic version of the original triiodothyronine (T3)-uptake assay called "T-uptake." We evaluated the ability of five such assays (Access, ES-300, IMx, Magnum Opus, and Stratus) ...

Pregnancy has a variety of effects on maternal thyroid function. Thyroid gland enlargement is common particularly in areas of relative iodine deficiency. The renal clearance of iodine is increased in pregnancy and together with an increased volume of iodine distribution, leads to a low plasma inorganic iodine and thus increases the thyroidal iodine clearance. However, the absolute iodine uptake...

Thyroid hormones are extremely important for development of the fetal central nervous system. Thyroidectomy results in severe hypothyroidism. In this study two levels of maternal hypothyroidism were reached by administration of different amounts of thyroxine (T4) and 3,5,3'-tri-iodothyronine (T3) to thyroidectomized pregnant rats. We examined the production, distribution and transport of T4 and...

Thyroid gland explant cultures from prometamorphic Xenopus laevis tadpoles were evaluated for their utility in assessing chemicals for thyroid hormone (TH) synthesis disruption. The response of cultured thyroid glands to bovine thyroid stimulating hormone (bTSH) and the TH synthesis inhibitors methimazole, 6-propylthiouracil, and perchlorate was determined. Thyroid glands continuously exposed f...