title: Effect of vitamin D3 loading and thyroid hormone replacement therapy on the decreased serum 25-hydroxyvitamin D level in patients with hypothyroidism.
abstract: Twelve hypothyroid subjects, 13 healthy and 12 healthy women with a slight deficiency of vitamin D were studied to distinguish seasonal changes from the thyroxine-dependent ones. Serum 25-hydroxyvitamin D levels of hypothyroid patients were lower than those of healthy individuals when the sera were obtained in the autumn. In hypothyroid patients a single oral dose of 100,000 IU vitamin D3 resulted in a smaller increase in 25-hydroxyvitamin D concentration than in controls having subclinical exogenous vitamin D deficiency. Substitution therapy with thyroid hormone, started in our study always in autumn, increased the 25-hydroxyvitamin D concentration in hypothyroid patients, which was opposite to the autumn-to-spring variation of this hormone observed in healthy controls. The increase of 25-hydroxyvitamin D, dehydroepiandrosterone and its sulphate values following substitution therapy in the hypothyroid patients may indicate that thyroid hormone(s) is (are) involved in the regulation of steroid hormone synthesis.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002112:Calcifediol / Q000097:blood*; D002762:Cholecalciferol / Q000494:pharmacology*; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives / Q000097:blood; D019314:Dehydroepiandrosterone Sulfate; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D012621:Seasons; D013963:Thyroid Hormones / Q000627:therapeutic use*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood
chemical_list: D013963:Thyroid Hormones; D002762:Cholecalciferol; D003687:Dehydroepiandrosterone; D019314:Dehydroepiandrosterone Sulfate; D013972:Thyrotropin; D002112:Calcifediol; D013974:Thyroxine