Vitamin D resistant hypophosphataemic osteomalacia: treatment with 1alpha-hydroxyvitamin D3

Ten patients with vitamin D resistant hypophosphataemic osteomalacia are described. They had hypophosphataemia with a decreased tubular reabsorption of phosphate, malabsorption of calcium and phosphorus, proximal myopathy and extensive osteomalacic changes on iliac crest bone biopsy. The plasma alkaline phosphatase and urine hydroxyproline, however, were raised in only some of the patients. Treatment with 1alpha-hydroxyvitamin D3 in high doses rapidly cured the myopathy, increased calcium and phosphorus absorption and retention and healed the osteomalacia. Phosphorus supplements were not required.