Effect of parathyroid hormone on vitamin D metabolism in osteopetrosis.
Indices of vitamin D metabolism were studied before and after infusion of bovine parathyroid hormone extract in three children with osteopetrosis. Basal serum concentrations of calcium, alkaline phosphatase, and 25-hydroxyvitamin D tended to be low. Serum immunoreactive parathyroid hormone levels were in the upper normal range in two patients. A marked increase in urinary cyclic adenosine 3':5'-monophosphate (cAMP) in all patients was solely due to an increase in the nephrogenous cAMP. The basal concentration of 1,25-dihydroxyvitamin D was clearly more than the upper limit of normal range in all three patients and increased after parathyroid extract infusion in one patient. The basal serum levels of 24,25-dihydroxyvitamin D were within normal limits and tended to decrease after parathyroid extract infusion in two of the patients. Parathyroid hormone and 1,25-dihydroxyvitamin D act in concert to increase calcium resorption from bone, and the increased serum levels of both these factors may reflect lack, or unresponsiveness, of target cells in bone.
D002648:Child; D002675:Child, Preschool; D000242:Cyclic AMP / Q000378:metabolism; D004100:Dihydroxycholecalciferols / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D010022:Osteopetrosis / Q000378:metabolism* / Q000503:physiopathology; D010281:Parathyroid Hormone / Q000494:pharmacology*; D014807:Vitamin D / Q000378:metabolism*
D004100:Dihydroxycholecalciferols; D010281:Parathyroid Hormone; D014807:Vitamin D; D000242:Cyclic AMP