Pseudohypoparathyroidism: a difficult diagnosis in early childhood.

We have studied one adult and three children with pseudohypoparathyroidism and observed that the physical character of short metacarpal bones is not evident in the first 4-5 years of life, that hypocalcaemia and hyperphosphataemia may be absent in the first years of life, but that the renal unresponsiveness to parathyroid hormone can still be demonstrated. Our data confirm earlier observation that in evaluating the renal responsiveness to parathyroid hormone, urinary cyclic AMP is a better parameter than urinary phosphorus. Thus in early childhood, it may be difficult to differentiate between a normal child, a child with pseudohypoparathyroidism and a child with pseudo-pseudohypoparathyroidism unless the renal parathyroid hormone responsiveness is studied.