Subject thyrotropin

The time-course of the prolactin increase has been examined in 17 subjects whose prolactin concentrations rose during the first 6-9 days of treatment with haloperidol (473). The increase was followed by a plateau that persisted, with minor fluctuations, throughout the 18 days of observation. Patients whose prolactin concentrations increased above 77 ng/ml (n = 2) had hypothyroidism, and it is known that TRH (thyrotropin) stimulates the release of prolactin (474). 

The metabolism of GSLs has been studied in cultured human fibroblasts from normal subjects, patients with lipid storage diseases, and those with FH. The content of the GSLs, as well as activities of the biosynthetic enzymes, the glycosyltransferases and the lysosomal GSL hydrolases,have been studied. Complex gangliosides, such as M1, GDla, have been found in this cell system to serve as receptors for cholera toxin and thyrotropin, respectively (24-26). More recently, GT1 and GDla have been postulated to be receptors for fibronectin in cultured fibroblasts... 

Waritz RS, Steinberg M, Kinoshita FK, Kelly CM, Richter WR (1996) Thyroid function and thyroid tumors in toxaphene-treated rats. Regul Toxicol Pharmacol 24 184-192 Weeke J (1973) Circadian variation of the serum thyrotropin level in normal subjects. Scand J Clin Lab Invest 32 337... 

Erfurth EM, Schutz A, Nilsson A, et al. 1990. Normal pituitary hormone response to thyrotropin and gonadotropin releasing hormones in subjects exposed to elemental mercury vapour. Brit J Ind Med 47 639-644. 

J. Lekakis, C. Papamichael, M. Alevizaki, G. Piperingos, P. Marafelia, J. Mantzos, S. Stamatelopoulos, D. A. Koutras, Flow-mediated, endothelium-dependent vasodilation is impaired in subjects with hypothyroidism, borderline hypothyroidism, and high-normal serum thyrotropin (TSH) values, Thyroid 7, 411-4 (1997). 

Effects on the Pituitary. Somatostatin inhibits GH and thyrotropin releasing hormone (TRH)-induced thyroid stimulating hormone (TSH) release from the pituitary. No effects on other pituitary hormones were observed in normal subjects. The inhibition of GH release by somatostatin suggests a use in the treatment of acromegaly. The value of GH release inhibition as long-term therpay cannot be predicted. 

Winokur et al.82 infused L-tryptophan intravenously into 11 healthy male subjects and studied plasma hormone levels. Significant increases were observed in plasma growth hormone and prolactin concentrations after L-tryptophan was given compared to saline-infused controls. No alterations in cortisol or thyrotropin levels were noted. Also, in experimental animals,... 

Figure 71.12 Thyroid hormone concentrations after iodine and seienium suppiementation. Mean ( SE) serum thyroxine (T4), triiodothyronine (T3) and thyrotropin (TSH) concentrations in the piacebo-iodine suppiemented subjects (O circies), and in the seienium-iodine-suppiemented subjects ( circies). The reference range for serum TSH concentrations is within the dotted iine. For serum TSH, bars indicate the vaiues 1 SE beiow and 1 SE above the mean on the iogarithmic scaie. A significant main effect of time was observed for serum T4 (P < 0.001), T3 (P < 0.001), and TSH (P = 0.011). Significantly different from all subsequent values, P < 0.001 (Heimert contrast). For serum T3, there was a significant main effect of group (P = 0.03). Reproduced with permission from Moreno-Reyes et al., (2003). The American Society for Nutrition.

Among the subjects with positive TPO antibody and normal thyrotropin at baseline, the 5-year cumulative incidence of hypothyroidism was 6.5 and 9.8 times in MAI and El compared with that in MDI. Among the subjects with positive thyroglobufin antibody and normal thyrotropin at basehne, the five-year cumulative incidence of hypothyroidism was 4.3 and 10.3 times in MAI and El, compared with that in MDI (Figure 125.2). Reinhardt et al. (1998) reported that after supplementing iodine at 250 j,g/ day to patients with Hashimotos thyroiditis (MUI, from 70p,g/g of creatinine, rose to 268p,g/g of creatinine), 20% of the patients were found to have hypothyroidism after 4 months, but only 2% of the patients with Hashimotos... 

Figure 125.2 The cumulative incidence of supranormai thyrotropin levels among subjects with euthyroidism and high levels of TPO antibody or thyrogiobuiin antibody iodine intake was mildly deficient in Panshan, more than adequate in Zhangwu, and excessive in Huanghua. The cumulative incidence increased with increasing iodine intake.

Figure 125.5 Levels of thyrotropin in euthyroid subjects from three communities with different levels of iodine intake. In the baseline study, we separated out 228 persons (6.1% of 3761 participants) who reported a family history of thyroid diseases, 126 persons (3.4%) who reported a personal history of thyroid disorders, 511 persons (13.6%) with high serum autoantibody values, and 1155 persons (30.7%) who had goiter and/or nodules and/or abnormal echo patterns in thyroid ultrasonography, leaving a sample group of 2237 individuals (636 in Panshan, 855 in Zhangwu, 743 in Huanghua) who composed the reference population. It was clearly shown that there was a urinary iodine-related increment of serum TSH levels (r = 0.21, P = 0.000). The median levels of TSH in the reference populations from Panshan (mild iodine deficiency), Zhangwu (more than iodine adequacy) and Huanghua (iodine excess) were 1.22, 1.41, and 1.99mlU/l, respectively (P = 0.000).

Figure 125.6 The cumulative incidence of abnormal levels of serum thyrotropin at 5 years among 2727 subjects who had normal levels of serum thyrotropin at baseline. The relationship between the baseline thyrotropin levels in 1999 and the cumulative incidence in 2004 of supranormal serum thyrotropin levels (above 4.8mlU/l) (panel a) or subnormal serum thyrotropin levels (below 0.3mlU/l) (panel b) is shown. A serum thyrotropin level above 1.9mlU/l (filled circle in panel a) was associated with an increased incidence of a supranormal thyrotropin level a drop in serum thyrotropin level below 1. OmIU/l (filled circle in panel b) was associated with an increased incidence of a subnormal thyrotropin level.

PiG. 4. Mean response to thyrotropin-releasing hormone (200 ng i.v.) in males (---, 20 subjects) and in females (—, 25 subjects). TSH, thyroid-stimulating hormone. 

Fig. 7. Serum thyroid-stimulating hormone (TSH) response to thyrotropin-releasing hormone (TRH) in normal subjects and in patients with hyperthyroidism and primary hypothyroidism. Ordinate serum immunoreactive TSH ( iU/ml). S, Normal controls (n = 45) primary hypothyroidism (n " 26), serum TSH > 21 20 minutes after TRH E3, thyrotoxicosis (n = 35), serum TSH < 1.8...

Prolactin secretion by pituitary cell cultures is inhibited by GH-RIH, but to a lesser extent than GH (VI). GH-RIH does not appear to affect basal PRL levels in normal subjects, but it has been reported to lower PRL release by otherwise normal pituitary cells when its secretion has been elevated by hypothyroidism or by chronic administration of estrogens. It does not affect the fall in PRL produced by i-dopa (S8) nor the rise in PRL resulting from insulin-induced hypoglycemia (H3) or thyrotropin-releasing hormone (Cl). Further critical studies of the effect of GH-RIH on basal circulating PRL levels are required. 

Wl. Weeke, J., The influence of the circadian rhythm on the thyrotropin response to thyrotropin releasing hormone in normal subjects. Scand. J. Clin. Lab. Incest. 33, 17-20 (1974). 

Uses Treatment with the thionamides thia-mazole (carbimazole), its active metabolite methimazole, or propylthiouracil remains one of the main therapeutic methods in hyperthyroidism. Unlike treatment with or surgery, thionamides are not ablative and permanent remission rates are low, even after prolonged administration. Suppression of serum thyrotropin (TSH) when antithyroid drugs are discontinued is a poor prognostic indicator of cure [13 ]. In a retrospective study there were higher remission rates at 6,12, and 24 months after withdrawal of antithyroid drugs in 40 subjects who had mild hypothyroidism (serum TSH over 10 pIU/l) compared with 37 sex- and age-matched patients who remained euthyroid during treatment with... 

Chopra K, Hershman J, Hornabrook R. 1975. Serum thyroid hormone and thyrotropin levels in subjects from endemic goiter regions of New Guinea. J.Clin.Endocrinol.Metab. 40 326. 

Thyrotropin-releasing factor (TRF) has been the subject of numerous H and NMR studies. The small size of the peptide renders it amenable... 

Thyroid dysfunction continues to be an infrequent and unpredictable complication found in only 3% of patients according to one review (47 ) and occurring more often in women. A study of the mechanism of action (50 ) in 17 patients on lithium maintenance therapy involved exploration of the hypothalamic-pituitary-thyroid axis. Fourteen subjects showed an exaggerated thyrotropin response to intravenous thyrotropinreleasing hormone that persisted during lithium therapy. However, only 2 of these patients showed any clinical or biochemical evidence of hypothyroidism both showed a delayed recovery of normal TRH response after discontinuing lithium. 

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