Serum 1,25-dihydroxyvitamin D concentration in hypophosphatemic vitamin D-resistant rickets.
Fasting serum 1 alpha, 25-dihydroxyvitamin D [1,25-(OH)2D] levels were measured in 3 groups of hypophosphatemic vitamin D-resistant rickets (VDRR) patients; those untreated; those treated with vitamin D and phosphate; and those treated with 1,25-(OH)2D3 and phosphate. In the untreated patients, the mean 1,25-(OH)2D level was higher than in our age-matched control group. Except for one at 66 pg/ml, individual values were however within normal limits. Long term vitamin D2 therapy was accompanied by a slight but significant decrease in 1,25-(OH)2D concentrations; nonetheless the levels remained within the normal range. In the third group of patients, the concentration of 1,25-(OH)2D rose to supranormal levels when sampling was done 1-3 hours after administration of the hormone, decreasing rapidly to levels below that of normal subjects when the specimens were collected 12-24 hours later. Our data show that an alteration of the vitamin D activation pathway is unlikely to be part of the pathogenic mechanism underlying the VDRR condition.
D000293:Adolescent; D000469:Alkaline Phosphatase / Q000097:blood; D002117:Calcitriol; D002648:Child; D002675:Child, Preschool; D004100:Dihydroxycholecalciferols / Q000097:blood*; D004872:Ergocalciferols / Q000627:therapeutic use; D005260:Female; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood*; D007015:Hypophosphatemia, Familial / Q000097:blood* / Q000188:drug therapy; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood* / Q000627:therapeutic use
D004100:Dihydroxycholecalciferols; D004872:Ergocalciferols; D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D010710:Phosphates; D000469:Alkaline Phosphatase; D002117:Calcitriol