Use of Phosphate and Vitamin D to Prevent Dwarfism and Rickets in X-Linked Hypophosphatemia

Abstract

Eight children with X-linked hypophosphatemia (three girls and five boys between three and 15 years of age) were treated for a total of 11,297 patient days with an inorganic phosphate salt supplement by mouth (1 to 4 g of inorganic phosphate per day in five divided doses given at four-hour intervals) and vitamin D₂ (10–50 X 10³ U per day). On this regimen the mean value for serum phosphorus in the group was 4.0 mg per 100 ml, and 85 per cent of values were above 3.0 mg per 100 ml. Radiographic evidence of rickets completely resolved, and an accelerated growth rate was observed in all patients when phosphate supplements were provided continuously. Dwarfism was corrected in three female and two male subjects. The whole-blood oxygen pressure at 50 per cent oxygen saturation was low (24.5 mm Hg at pH 7.4) in untreated patients but was restored to normal during phosphate treatment. There were no serious episodes of hypercalcemia, and no ectopic calcification was found.