The development of pseudohypoparathyroidism. Involvement of progressively increasing serum parathyroid hormone concentrations, increased 1,25-dihydroxyvitamin D concentrations, and 'migratory' subcutaneous calcifications.

The hormonal changes in the development of pseudohypoparathyroidism ( PSH ) have not, to our knowledge, been previously reported. The male sibling of a child with PSH was studied for 2 1/2 years. At 1 year of age he had generalized subcutaneous calcifications that subsequently migrated over his body. At 3 years of age and over a six-month period, serum calcium levels fell; serum phosphorus, parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D (1,25-[OH]2D) concentrations increased. There was no calcemic, phosphaturic, or urinary cyclic adenosine monophosphate response to PTH. The concentration of serum PTH was suppressed by infusion of calcium and doubled with edetic acid infusion, indicating that the parathyroids were sensitive to changes in calcium levels. Thus, increasing PTH and increased 1,25-(OH)2D concentrations occur in the development of PSH . Migratory skin calcifications may occur. We speculate that increasing the serum PTH level reflects increasing compensatory parathyroid production to overcome a progressive PTH receptor defect and serves, with increased 1,25-(OH)2D concentrations, to prevent severe falls in serum calcium concentrations in the early stage of the disease.