Serum 1,25-dihydroxyvitamin D concentration in hypophosphatemic vitamin D-resistant rickets
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Fasting serum 1α,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.
Calcitriol (1α,25-(OH)2D3) as RocaltrolR in capsules of 0.25 and 0.50 µg was kindly supplied by Dr. Patrick Le Morvan (Hoffmann-La Roche Ltd, Vaudreuil, Que., Canada).
Key wordsVitamin D-resistant rickets hypophosphatemia 1,25-dihydroxyvitamin D 1,25-(OH)2D calcitriol
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- 2.Chan, J.C.M., Bartter, F.C.: Hypophosphatemic rickets: Effects of 1α,25-dihydroxyvitamin D on growth and mineral metabolism, Pediatr.64:488–495, 1979Google Scholar
- 4.Haussler, M., Hughes, M., Baylink, D., Littledike, E.T., Cork, D., Pitt, M.: Influence of phosphate depletion on the biosynthesis and circulating level of 1α,25-dihydroxyvitamin D, Adv. Expt. Med. Biol.81:233–250Google Scholar
- 9.Tanaka, Y., DeLuca, H.F.: The control of 25-hydroxyvitamin D metabolism by inorganic phosphorus, Arch. Biochem. Biophys.154:566–574Google Scholar
- 12.Trechsel, U., Eisman, J.A., Fischer, J.A., Bonjour, J.-P., Fleisch, H.: Calcium-dependent, parathyroid hormone-independent regulation of 1,25-dihydroxyvitamin D, Am. J. Physiol.2:119E-124E, 1980Google Scholar
- 13.Chesney, R.W., Mazess, R.B., Rose, P., Hamstra, A.J., DeLuca, H.F.: Supranormal 25-hydroxyvitamin D and subnormal 1,25-dihydroxyvitamin D: their role in X-linked hypophosphatemic rickets, Am. J. Dis. Child.134:140–143Google Scholar
- 15.Glorieux, F.H., Bordier, P.J., Marie, P., Travers, P., Delvin, E.E., Pettifor, J.M.: The response of bone to oral phosphate salts, ergocalciferol and/or 1α,25-dihydroxycholecalciferol in familial hypophosphatemia. In A.W. Norman, K. Schaefer, D. von Herrath (eds). Vitamin D: Basic Research and its Clinical Application, pp. 1163–1165. Walter de Gruyter, Berlin, 1979Google Scholar