triiodothyronine--reverse and Adenoma

The secretion rates of T4, T3, and rT3 were studied in experiments of short duration by a new method based on determinations of the hormone difference across the thyroid combined with simultaneous electromagnetic thyroid blood flowmetry during surgery in 70 euthyroid patients. The secretion rate of T3 was similar in normal thyroid tissue and nodular goitre, but those of T4 and rT3 were lower in nodular goitre and solitary adenoma (P less than 0.05). In 61 patients with normal thyroid tissue or nodular goitre the secretion rates during surgery (mean +/- SEM) were for T4 222 +/- 28 nmol/day, for T3 27.4 +/- 3.1 nmol/day, and for rT3 3.5 +/- 0.5 nmol/day. In relation to the individual T4 secretion rate, the secretion rate of T3 was 12.5 +/- 3.0% and that of rT3 1.2 +/- 0.9%. In these short-term experiments we found a secretion rate for T4 during operation about 50% greater than in earlier long-term kinetic studies, but which tallied with a recent report using a 4-compartment model. For T3 and rT3 it was 2-3 times greater than earlier estimates. The secretion was estimated to be 50% of the total production rate for T3 and 6% for rT3. If proportional adjustment were performed to yield a T4 secretion of about 130 nmol/day. T3 and rT3 secretion rates would still be greater than earlier reported.

Topics: Adenoma; Adult; Aged; Carcinoma; Electromagnetic Phenomena; Female; Goiter; Goiter, Nodular; Humans; Hyperparathyroidism; Intraoperative Period; Male; Middle Aged; Rheology; Surgical Procedures, Operative; Thyroid Gland; Thyroid Neoplasms; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Morphological and functional properties of dispersed cells of human adenomatous goiter and those of the thyroid tissue adjacent to and distant from the nodular lesion (normal control) were investigated. In the presence of TSH, reconstructive arrangement of adenomatous goiter cells into a three-dimensional follicular structure occurred in a similar manner to that of normal controls. An addition of thyrotropin (TSH) to culture resulted in the secretion of thyroid hormones in control cells, but adenomatous goiter cells showed no response to TSH. It was found that the ratio of rT3, T3, the ratio of an inactive to an active form, was about three times higher in adenomatous goiter than in normal control. These findings suggested that conversion from T4 to rT3 is increased in adenomatous goiter.

Topics: Adenoma; Cells, Cultured; Goiter; Humans; Thyroid Hormones; Thyroid Neoplasms; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Serum concentrations of TSH, TT4, TT3 and rT3 were monitored for one month after excision of ten autonomous thyroid adenomas which had suppressed TSH secretion. Basal serum TSH levels start to increase between 30 hr and 20 days after surgery reaching normal and steady levels by the 24 day. Serum TT3 concentrations rapidly decrease in the first 20 hr to values near the lower limit of the normal range. Thereafter TT3 levels change little until pituitary TSH secretion recovers. Serum TT4 levels also fall, but much more slowly than TT3. Rising TSH levels stimulate residual extranodular thyroid tissue secretion of both TT3 and TT4. However, serum TT3 levels rise more rapidly than TT4 levels. Preoperative serum concentrations of both TT4 and TT3 are related directly to the time required until the beginning of the postoperative rise in TSH levels, and inversely with the maximal postoperative serum TSH concentration achieved. Throughout the study period, for all patients, serum TSH concentrations were inversely related to serum TT4 concentrations. These data suggest that, although the time required until the onset of recovery of TSH secretion is directly related to preoperative levels of TT4 and TT3, the regulation of postoperative TSH levels is dependent upon serum TT4 levels. Also, the serum TT3 levels constant at the lower limit of the normal range before recovery of TSH secretion, and the preferential rise in serum TT3 concentrations associated with rising TSH secretion, may prevent or abbreviate temporary postoperative hypothyroidism.

Topics: Adenoma; Adult; Aged; Female; Humans; Middle Aged; Pituitary Gland, Anterior; Thyroid Gland; Thyroid Hormones; Thyroid Neoplasms; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

The thyroid hormone concentrations of T2, T3 (and the inactive R-T3) were determined in thyroid tissue of 20 patients with autonomous adenomas. High concentrations were found in scintigrafically decompensated adenomas without preoperative thyrostatic treatment. Decompensated adenomas after thyrostatic treatment, compersated adenomas and a group of 9 euthyroid goiters showed no difference in tissue-concentrations of T4 and T3. The amount of tissue-R-T3 seems to be lowered in autonomy. The plasma-concentration of T3, which was intraoperatively elevated in the venous effluent from decompensated adenomas without thyrostatic treatment, was significantly lower in the blood draining decompensated adenomas after thyrostatic treatment as well as compensated adenomas.

Topics: Adenoma; Antithyroid Agents; Humans; Thyroid Gland; Thyroid Hormones; Thyroid Neoplasms; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse