title: The importance of phosphate in regulating plasma 1,25-(OH)2-vitamin D levels in humans: studies in healthy subjects in calcium-stone formers and in patients with primary hyperparathyroidism.
abstract: We observed that plasma 1,25-(OH)2-D concentrations average 87 +/- 30 SD pmol/l in 48 healthy adults without a personal or family history of kidney stones. Plasma 1,25-(OH)2-D concentrations were significantly elevated among 26 patients with recurrent calcium-containing renal stones and hypophosphatemia: 150 +/- 74 pmol/l; P less than 0.001, and among 9 patients with proven parathyroid adenoma and hypophosphatemia: 200 +/- 54 pmol/l; P less than 0.001. Plasma 1,25-(OH)2-D levels in these 3 groups were inversely correlated with serum phosphate concentration: plasma 1,25-(OH)2-D, pmol/l = 282 - 141 X serum PO4, mmol/l; r = 0.51; P less than 0.001. During dietary PO4 deprivation lasting 11 to 16 days in 10 healthy women, serum PO4 fell and plasma 1,25-(OH)2-D concentrations rose whereas in 8 healthy men neither serum PO4 nor 1,25-(OH)2-D concentrations changed. The change from control in plasma 1,25-(OH)2-D levels were correlated with the change from control in serum PO4 concentrations: delta1,25-(OH)2-D, pmol/l = 1 - 82 X delta serum PO4 mmol/l; r = 0.59; P less than 0.01. We conclude that reductions in serum PO4 concentrations, either directly or indirectly, stimulate renal synthesis of 1,25-(OH)2-D in humans.
mesh_terms: D000328:Adult; D002118:Calcium / Q000378:metabolism*; D004100:Dihydroxycholecalciferols / Q000097:blood*; D005260:Female; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood*; D006961:Hyperparathyroidism / Q000097:blood*; D007669:Kidney Calculi / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000378:metabolism*; D006435:Renal Dialysis
chemical_list: D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D010710:Phosphates; D008274:Magnesium; D002118:Calcium