Decrease In Thyroid-stimulating Hormone Levels Research Articles

Effects of levonorgestrel implant upon TSH and LH levels in male infants during lactation

Objectives: The objective of the study is to evaluate the effects of levonorgestrel transferred through breast milk on thyroid stimulating hormone (TSH) and luteinizing hormone (LH) levels in full breast-fed infants. Methods: Forty healthy postpartum women and their male newborns were recruited for the study. Women were randomly allocated to two study groups: Group 1, IUD users and group 2, Norplant ® users. Blood and milk samples were collected on the day of IUD or Norplant ® insertion and 3 and 6 months later for TSH and levonorgestrel measurements. Results: The results disclosed a significant decrease in TSH levels, and a negative relationship between LNG levels and TSH concentration in breast feeding infants at 3 months after implant insertion. The lowest TSH levels were observed at 6 months in the women from group 2. Conclusions: The overall data indicate that the LNG levels transferred to fully breast-fed infants through breast milk from Norplant ® users significantly modified their TSH levels.

Inhibition of experimentally induced cirrhosis in rats by hypothyroidism

The coexistence of hyperkinetic circulation, hypermetabolism, and hyperactivity of the sympathetic nervous system is encountered in both cirrhosis and hyperthyroidism. Several drugs, such as propylthiouracil and propranolol, that are beneficial for treating some patients with chronic liver diseases are also prescribed for the treatment of thyrotoxicosis. We investigated the effects of experimentally induced hypo- and hyperthyroidism on the development of cirrhosis induced in rats by thioacetamide (TAA). We specifically examined whether hypothyroidism could prevent and hyperthyroidism could aggravate liver damage. Hypothyroidism induced by methimazole (MMI, 0.04%), propylthiouracil (PTU 0.05%), and by thyroidectomy was confirmed by a significant elevation of thyroid-stimulating hormone (TSH) levels. Hyperthyroidism (decreased TSH levels) was induced by eltroxin (ELT: 50 micrograms/kg). Thirteen groups of 10 rats each were studied: euthyroid controls (3 groups: water, TAA 1.5 months, and TAA 3 months), hypothyroid (6 groups: MMI, PTU, surgical, MMI-TAA, PTU-TAA, surgical-TAA), and hyperthyroid (4 groups:ELT 1.5 months and 3 months, and ELT-TAA for 1.5 months and 3 months). Hepatic fibrosis (scored from 0 to 3) was significantly reduced (P < .0001) in hypothyroid rats as compared with euthyroid controls, and was aggravated in TAA-treated hyperthyroid rats (P < .0001). Quantitative microscopic analysis of liver biopsy specimens from all groups confirmed the semiquantitative histopathological scores (P < .001). Direct intrasplenic pressure measurement revealed a significant portal pressure elevation in the TAA and the ELT-treated rats (from 4.7 +/- 0.1 in the euthyroid group to 8.1 +/- 2.3 and 10.2 +/- 2.1 and 12.5 +/- 1.6 in the TAA, ELT and ELT- TAA groups, respectively). However, in the hypothyroid-TAA groups, the portal pressure was found to be within the euthyroid normal range (4.6 +/- 1.2 and 5.8 +/- 0.6 in the PTU-TAA and surgical-TAA, respectively). After 12 weeks, the mean spleen weight of rats receiving only TAA was significantly higher than the TAA-treated hypothyroid rats (P < .0001), indicating that the hypothyroid TAA-treated rats were less portal hypertensive. These results suggest that induced hypothyroidism can inhibit, whereas hyperthyroidism can aggravate, the development of cirrhosis in a rat model. (Hepatology 1996 Aug;24(2):419-23)

Inhibition of Experimentally Induced Cirrhosis in Rats by Hypothyroidism

The coexistence of hyperkinetic circulation, hypermetabolism, and hyperactivity of the sympathetic nervous system is encountered in both cirrhosis and hyperthyroidism. Several drugs, such as propylthiouracil and propranolol, that are beneficial for treating some patients with chronic liver diseases are also prescribed for the treatment of thyrotoxicosis. We investigated the effects of experimentally induced hypo– and hyperthyroidism on the development of cirrhosis induced in rats by thioacetamide (TAA). We specifically examined whether hypothyroidism could prevent and hyperthyroidism could aggravate liver damage. Hypothyroidism induced by methimazole (MMI, 0.04%), propylthiouracil (PTU 0.05%), and by thyroidectomy was confirmed by a significant elevation of thyroid–stimulating hormone (TSH) levels. Hyperthyroidism (decreased TSH levels) was induced by eltroxin (ELT: 50 micrograms/kg). Thirteen groups of 10 rats each were studied: euthyroid controls (3 groups: water, TAA 1.5 months, and TAA 3 months), hypothyroid (6 groups: MMI, PTU, surgical, MMI–TAA, PTU–TAA, surgical–TAA), and hyperthyroid (4 groups:ELT 1.5 months and 3 months, and ELT–TAA for 1.5 months and 3 months). Hepatic fibrosis (scored from 0 to 3) was significantly reduced ( P &lt; .0001) in hypothyroid rats as compared with euthyroid controls, and was aggravated in TAA–treated hyperthyroid rats ( P &lt; .0001). Quantitative microscopic analysis of liver biopsy specimens from all groups confirmed the semiquantitative histopathological scores ( P &lt; .001). Direct intrasplenic pressure measurement revealed a significant portal pressure elevation in the TAA and the ELT–treated rats (from 4.7 ± 0.1 in the euthyroid group to 8.1 ± 2.3 and 10.2 ± 2.1 and 12.5 ± 1.6 in the TAA, ELT and ELT– TAA groups, respectively). However, in the hypothyroid–TAA groups, the portal pressure was found to be within the euthyroid normal range (4.6 ± 1.2 and 5.8 ± 0.6 in the PTU–TAA and surgical–TAA, respectively). After 12 weeks, the mean spleen weight of rats receiving only TAA was significantly higher than the TAA–treated hypothyroid rats ( P &lt; .0001), indicating that the hypothyroid TAA–treated rats were less portal hypertensive. These results suggest that induced hypothyroidism can inhibit, whereas hyperthyroidism can aggravate, the development of cirrhosis in a rat model.

832 Acute radiation-induced thyroiditis—A prospective study

Purpose We prospectively studied acute radiation-induced thyroid dysfunction by performing thyroid function tests. Materials and methods The subjects were 28 patients who underwent neck irradiation incidentally including the thyroid for various malignancies. The total dose absorbed by the thyroid was 4500–5000 cGy. Thyroid function tests included serum thyroid stimulating hormone (TSH), free triiodothyronine (T3), and free thyroxine (T4). These data were obtained before irradiation, at 40 Gy irradiation, and 3 and 6 months thereafter. Results Mean TSH levels were 1.57,0.66, 1.34, and 6.23 μU/ml at preirradiation, 40 Gy irradiation, and 3 and 6 months after irradiation, respectively. The decrease in TSH levels at 40 Gy was significant (P = 0.0001, Wilcoxon signed-rank test). TSH levels significantly increased thereafter until 6 months (40 Gy vs 3 months:P = 0.001,3 months vs 6 months:P = 0.028). Mean T4 levels increased from 1.13 to 1.21 ng/ml during 40 Gy irradiation (P = 0.02). Conclusion The elevation of T4 and decrease in TSH observed at the time of irradiation was attributed to acute thyroid follicular cell destruction by irradiation.

Treatment of thyroid-stimulating hormone-secreting adenomas with octreotide

From data collected in the literature, the effects of octreotide therapy in 37 patients with thyroid-stimulating hormone (TSH)-secreting adenomas who received short-term (1 to 2 weeks, n = 23) and long-term treatment (3 to 36 months) are reviewed. In 20 of 21 patients studied, short-term administration of octreotide (50 or 100 μg subcutaneously [SC] produced a 25% to 100% (mean ± SD, 55.3% ± 29%) decrease in TSH levels, with the nadir being obtained between the third and sixth hour following injection. After 1 to 2 weeks therapy with 50 to 100 μg twice or three times a day, 21 of 23 patients studied demonstrated a 66% (±30%) decrease in TSH levels and 14 of 16 showed a 64% (±27%) decrease in α-subunit levels. In approximately two thirds of the patients, the response was better than after short-term administration. The effect of octreotide on clinical and biological thyroid status was significant in all patients studied. After 1 week or 1 month of treatment, thyroid hormone levels were reduced in all patients and were normalized in 78%. Response to therapy was similar whether TSH secretion was pure or mixed (growth hormone [GH]-TSH adenomas). Fourteen patients received long-term treatment (3 to 36 months; mean, 12 ± 10) with daily doses ranging from 200 to 1,500 μg. The response was better than or similar to that with short-term treatment. An escape occurred in TSH levels in two patients and in thyroid hormone levels in three patients, leading to an adjustment of dose or frequency of injection. A partial shrinkage of the adenoma was demonstrated by a computerized tomography (CT) scan and/or magnetic resonance imaging (MRI) in six patients, with a 30% to 50% reduction occurring in three of these patients. In conclusion, octreotide may currently be considered the treatment of choice in TSH-secreting adenomas when surgery and/or radiotherapy have been unsuccessful. Octreotide reduced TSH secretion in almost all the patients, leading to normalization of thyroid hormone levels in three quarters; partial tumor shrinkage was observed in one third of the patients on long-term treatment.

Clinical and Subclinical Thyroid Disorders Associated With Pernicious Anemia

of 162 patients with pernicious anemia whom we studies, 24.1% had clinical thyroid disease; 11.7% were hypothyroid and 8.6% were hyperthyroid. When abnormal serum thyroid-stimulating hormone (TSH) levels were also considered, thyroid disorders existed in 48.3% of 143 patients. Increased or decreased TSH levels as the sole dysfunction occurred in 14.7% and 6.3% of cases, respectively, and were often associated with thyroid antibodies. The high TSH group fits the picture of subclinical hypothyroidism. The nature of the low TSH group remains to be defined. We conclude that TSH screening in patients with pernicious anemia uncovers frequent abnormalities, which are superimposed on a higher coincidence of overt thyroid disease than previously described. Interestingly, also, eight of nine hyperthyroid patients and all seven patients with low TSH levels had blood type O, contrasting significantly with hypothyroid subjects, who more often had blood type A, and with patients without thyroid disorders.