title: The importance of circulating 1,25-dihydroxyvitamin D in the pathogenesis of hypercalciuria and renal-stone formation in primary hyperparathyroidism.
abstract: Fifty patients with primary hyperparathyroidism were studied with an oral calcium-tolerance test, measurements of plasma levels of vitamin D metabolites, and determination of calcium excretion on both a low-normal (400 mg) and high-normal (1000 mg) calcium intake. There were strong positive correlations between plasma levels of 1,25-dihydroxyvitamin D (1,25(OH)2D) and both the calciuric response to the calcium-tolerance test (r = +0.75, P less than 0.001) and calcium excretion on the 1000-mg calcium diet (r = +0.65, P less than 0.001). The patients were classified into two subpopulations: 30 patients showed hyperabsorption with the calcium-tolerance test, striking hypercalciuria, marked elevations in plasma 1,25(OH)2D, and a high incidence (19 of 30 patients) of renal stones; 20 patients had a normal response to the tolerance test, normocalciuria, normal or high-normal plasma 1,25(OH)2D, and a low incidence of stones (three of 20 patients). The findings emphasize the importance of circulating 1,25(OH)2D in the pathogenesis of hypercalciuria and stone formation in primary hyperparathyroidism.
mesh_terms: D002118:Calcium / Q000652:urine*; D004100:Dihydroxycholecalciferols / Q000097:blood*; D005260:Female; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood*; D006961:Hyperparathyroidism / Q000097:blood* / Q000150:complications / Q000378:metabolism; D007669:Kidney Calculi / Q000209:etiology*; D008297:Male; D008875:Middle Aged
chemical_list: D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D002118:Calcium