Serum Parathyroid Hormone Concentrations in Vitamin D Deficiency Rickets of Infancy: Effects of Intravenous Calcium and Vitamin D

Abstract

Immunoreactive parathyroid hormone concentration in the serum (IPTH) was elevated in three normocalcaemic and in seven hypocalcaemic children with vitamin D deficiency rickets. In two normocalcaemic children treated with moderate amounts of vitamin D₃ serum ionized and total calcium remained in the normal range, when IPTH was normalised. In three hypocalcaemic patients receiving I.V. calcium infusions during two days, serum calcium returned to the lower level of the normal range while IPTH remained abnormally high. In these patients IPTH became normal following treatment with vitamin D₃ while serum ionized and/or total calcium remained in the normal range. In view of the inverse relationship between the serum calcium and IPTH levels and the fact that hypocalcaemia (and possibly hypomagnesaemia) are the only recognized stimulators of IPTH secretion, the present study suggests that vitamin D may have a direct action on parathyroid hormone secretion, vitamin D deficiency having a stimulating effect, and vitamin D treatment an inhibiting effect.

Key words

Parathyroid Hormone - Vitamin D - Vitamin D Deficiency Rickets