Parathyroid function in vitamin D deficiency rickets. I. Phosphorus excretion index in vitamin D deficiency rickets in South African Bantu infants.

Abstract

A study of South African Bantu infants with vitamin D deficiency rickets revealed marked elevation of the phosphorus excretion index (PEI) as measured by the method of Nordin and Fraser. This finding is interpreted as evidence of secondary hyperparathyroidism, since the PEI was depressed by intravenous calcium infusion. In view of the inverse relationship demonstrated between phosphorus excretion and the plasma phosphorus levels in these children it is suggested that secondary hyperparathyroidism may play a fundamental role in the evolution of the biochemical findings in this disease. An hypothesis is put forward to explain the histologic differences between rickets and primary hyperparathyroidism on the basis of the double action of parathyroid hormone. The PEI is a suitable technique for investigation of problems of calcium-phosphorus metabolism in childhood.