Vitamin D metabolism in hypophosphatemic rickets
R. S. Mason, P. G. Rohl, D. Lissner and S. Posen
Vitamin D metabolites were measured in 21 patients with hypophosphatemic
osteomalacia of juvenile onset. In eight patients who had not received any
antirachitic treatment, serum 25-hydroxyvitamin D(25-OH-D) and
1,25-dihydroxyvitamin D (1,25-[OH]2D) values were normal, whereas serum
24,25-dihydroxyvitamin D (24,25-[OH]2D) values were lower than in normal
subjects. In 13 patients who were receiving ergocalciferol and oral
elemental phosphorus, serum 25-OH-D and 24,25-(OH)2D concentrations were
elevated and serum 1,25-(OH)2D values were low. The findings in untreated
patients supported the hypothesis that vitamin D metabolism is abnormal in
hypophosphatemic rickets/osteomalacia. The reduction of serum 1,25-(OH)2D
levels with ergocalciferol and phosphate therapy gives further support to a
therapeutic role for 1,25-(OH)2D in this disorder.
