title: Reversible hypocalciuric hypercalcemia associated with hypothyroidism.
abstract: Hypothyroidism is known to affect calcium homeostasis by decreasing bone turnover and serum calcium level, and by increasing parathyroid hormone and 1,25-dihydroxyvitamin D concentrations. A 52-year-old hypothyroid woman is described who had hypercalcemia associated with elevated parathyroid hormone and 1,25-dihydroxyvitamin D levels, but decreased 24-hour urinary calcium excretion and ratio of calcium to creatinine clearance. These parameters normalized following thyroid hormone replacement therapy. Hypercalcemia appeared to result from a combination of reduced renal calcium excretion and a change in the "set point" for calcium feedback inhibition of the parathyroid glands. These data suggest that thyroid hormone has a direct effect on the parathyroid glands, regulating parathyroid hormone secretion, and on the kidney's ability to excrete calcium. It is recommended that parathyroid hormone, 1,25-dihydroxyvitamin D, and urinary calcium excretion values be interpreted in light of thyroid hormone status.
mesh_terms: D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood / Q000652:urine*; D003404:Creatinine / Q000652:urine; D005215:Fasting; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000209:etiology* / Q000652:urine; D006961:Hyperparathyroidism / Q000150:complications; D007037:Hypothyroidism / Q000150:complications* / Q000188:drug therapy / Q000652:urine; D008875:Middle Aged; D010280:Parathyroid Glands / Q000502:physiology; D010281:Parathyroid Hormone / Q000097:blood; D013974:Thyroxine / Q000502:physiology / Q000627:therapeutic use*
chemical_list: D010281:Parathyroid Hormone; D003404:Creatinine; D002117:Calcitriol; D013974:Thyroxine; D002118:Calcium