Abstract

Parathyroid hormone (PTH) in serum has been determined by a double antibody radioimmunoassay which is suitable for use in infants. The concentration in normal infants rose after birth from a mean level of 97 pg/ml in cord blood to 217 pg/ml at 6 days of age. It remained at this level in the older infants and children. In a group of infants with hypocalcaemia and many complicating factors, the PTH concentration was significantly lower than normal. All but one of the affected infants maintained a normal serum calcium without treatment 1 year after the episode of hypocalcaemia. It is suggested that prolonged immaturity of parathyroid function may contribute significantly to the aetiology of hypocalcaemia and may be related to immaturity of the mechanisms responsible for converting glandular PTH to secreted PTH.