tetracycline and Hyperthyroidism

Topics: Adolescent; Adult; Aged; Biopsy; Bone and Bones; Bone Development; Bone Diseases, Metabolic; Bone Resorption; Child; Child, Preschool; Female; Humans; Hyperparathyroidism; Hyperthyroidism; Infant; Male; Middle Aged; Osteogenesis; Osteoporosis; Tetracycline

Clinical studies in thyrotoxicosis reveal a state of high bone turnover leading, eventually, to osteoporosis. Recently there has been concern that thyroxine (T4) treatment may have a similar effect on bone. Rat models have been used to study the effects of T4 on bone, but the majority of studies have looked at the effects of T4 after only 3 weeks of treatment. The aim of this study was to evaluate histomorphometric changes in rats after 12 weeks of thyroxine overtreatment or 12 weeks of hypothyroidism compared with untreated control animals. Animals received either T4 200 micrograms/kg per day, 0.1% propylthiouracil, or vehicle for 12 weeks. Tetracycline was administered 1 week and 3 weeks prior to killing. Iliac crest bone was used for histomorphometry. Serum T4 measurements (taken at killing) confirmed hyper- and hypothyroidism in the appropriate animal groups (between group difference p < 0.001 by ANOVA). In hyperthyroid animals there was an increase in mineral apposition rate (MAR; 0.94 vs. 0.59 microns/day, p < 0.001) and mineral formation rate (MFR/BS; 0.24 vs. 0.12 x 10(-2) micron3/micron2 per day, p < 0.001) and a slight increase in eroded surfaces (ES/BS%; 1.54 vs. 1.36, p < 0.05) compared with controls, consistent with previous in vitro and in vivo observations. In hypothyroid rats there was a marked reduction in osteoid surfaces (OS/BS%; 1.7 vs. 24.8, p < 0.001) and MAR (0.3 vs. 0.59 micrograms/day, p < 0.001), a reduction in ES/BS% (0.51 vs. 1.36, p < 0.05), and an increase in cancellous bone volume (BV/TV%; 30.29 vs. 19.6, p < 0.05), suggesting that thyroid hormones are a requirement for normal bone turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Analysis of Variance; Animals; Body Weight; Calcinosis; Disease Models, Animal; Drug Overdose; Hyperthyroidism; Hypothyroidism; Ilium; Male; Propylthiouracil; Radioimmunoassay; Rats; Rats, Wistar; Tetracycline; Thyroid Function Tests; Thyroxine

Quantitative histomorphometric analyses of iliac crest biopsy specimens were performed after tetracycline double-labeling in 41 normal individuals, 20 hyper- and 10 hypothyroid patients, 18 patients with primary hyperparathyroidism, 20 epileptic patients receiving long-term anticonvulsant therapy, and 17 patients after jejunoileal bypass for morbid obesity. The mineralization lag time in trabecular bone or the period of time between apposition and subsequent mineralization of osteoid was calculated from the bone formation rate at BMU level (Basic Multicellular Unit) and the mean width of osteoid seams. The mineralization lag time was 8-52 days (median 21 days) in normal individuals and showed no variation with sex or age. The mineralization lag time was shortened in hyperthyroidism, normal in anticonvulsant bone disease and in primary hyperparathyroidism, and markedly prolonged in hypothyroidism and following jejunoileal bypass. Among all individuals an inverse hyperbolic relation (r = 0.94, p less than 0.001) was found between the mineralization lag time and the average cellular activity of the osteoblasts.

Topics: Adult; Aged; Biopsy; Bone and Bones; Bone Diseases; Female; Humans; Hyperparathyroidism; Hyperthyroidism; Hypothyroidism; Ileum; Ilium; Male; Middle Aged; Minerals; Obesity; Osteoblasts; Osteomalacia; Phenytoin; Postoperative Complications; Tetracycline; Time Factors

Increased bone, resorption previously found in hyperthyroidism might be caused by a direct stimulating effect of thyroid hormone(s) on bone cells or by an increased sensitivity to circulating parathyroid hormone. In order to disclose qualitative differences in the response of bone resorbing cells to excess parathyroid hormone and excess thyroid hormone(s), histomorphometric analysis of iliac crest biopsies was performed in 25 hyperparathyroid and 40 hyperthyroid patients after tetracycline double-labelling. The main target cells for parathyroid and thyroid hormones were different. Parathyroid hormone stimulated osteocytic osteolysis and increased osteoclastic resorption surfaces equally in trabecular and cortical bone. The osteoclastic resorption was inactive. Thyroid hormone(s) had no effect on osteocytes but increased the osteoclastic resorption surfaces in trabecular and cortical bone, with a pronounced preponderance in cortical bone. The osteoclastic resorption was active and followed by a significant loss of both cortical and trabecular bone. The findings support the assumption that increased bone resorption in hyperthyroidism is caused by a direct stimulating effect of thyroid hormone(s).

Topics: Adult; Aged; Bone and Bones; Bone Resorption; Calcium; Female; Humans; Hyperparathyroidism; Hyperthyroidism; Ilium; Male; Middle Aged; Parathyroid Hormone; Phosphorus; Tetracycline; Thyroid Hormones

Bone biopsies were performed after tetracycline double-labelling by transfixing the right iliac crest in forty hyperthyroid patients. The bone changes in cortical and trabecular bone were determined by simple measurement and point counting on decalcified and undecalcified stained sections. A slight decrease in the amount of cancellous bone was found. The mean cortical width was normal. The amount of osteoid and the length of the osteoid seams were increased, whereas the mean width of osteoid seams was decreased. The cortical osteoclastic activity and porosity were markedly increased. The trabecular osteoclasic activity was moderately increased and the mean size of periosteocytic lacunae was slightly increased. The calcification rate in cancellous bone was increased as were the active calcification surfaces (tetracycline-labelled). The osteoclastic activity in cortical bone was positively correlated to the free thyroxine index and to the urinary calcium and phosphorus excretion. The findings indicate that the bone changes in hyperthyroidism are specific and that thyroid hormone(s) stimulates both bone formation and resorption followed by increased porosity in cortical bone and by mobilization of bone mineral.

Topics: Adolescent; Adult; Age Factors; Aged; Biopsy; Bone and Bones; Bone Resorption; Calcinosis; Calcium; Female; Humans; Hyperthyroidism; Male; Middle Aged; Phosphorus; Tetracycline

Topics: Carbimazole; Chlorpromazine; Diabetes Mellitus; Diazepam; Drug Prescriptions; Epilepsy; Female; Fetus; Heparin; Humans; Hyperthyroidism; Infant, Newborn; Insulin; Maternal-Fetal Exchange; Pregnancy; Pregnancy Complications; Pregnancy Trimester, First; Smoking; Streptomycin; Tetracycline; Warfarin

Topics: Adolescent; Digoxin; Female; Humans; Hyperthyroidism; Infant; Infant, Newborn; Infant, Newborn, Diseases; Long-Acting Thyroid Stimulator; Phenobarbital; Prednisolone; Tetracycline; Thyroiditis