Serum 1,25-dihydroxyvitamin D concentration in hypophosphatemic vitamin D-resistant rickets

Calcif Tissue Int. 1981;33(2):173-5. doi: 10.1007/BF02409431.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Alkaline Phosphatase / blood
  • Calcitriol
  • Child
  • Child, Preschool
  • Dihydroxycholecalciferols / blood*
  • Ergocalciferols / therapeutic use
  • Female
  • Humans
  • Hydroxycholecalciferols / blood*
  • Hypophosphatemia, Familial / blood*
  • Hypophosphatemia, Familial / drug therapy
  • Male
  • Parathyroid Hormone / blood
  • Phosphates / blood*
  • Phosphates / therapeutic use


  • Dihydroxycholecalciferols
  • Ergocalciferols
  • Hydroxycholecalciferols
  • Parathyroid Hormone
  • Phosphates
  • Alkaline Phosphatase
  • Calcitriol