Subclinical pseudohypoparathyroidism type II: evidence for failure of physiologic adjustment in calcium metabolism during pregnancy.

Patients with latent disorders of hormone response mechanism are rarely found. This paper reports a case of subclinical pseudohypoparathyroidism type II in which physiological adjustment of calcium (Ca) metabolism became insufficient only in the second half of pregnancy. A 34-year-old woman examined for a slight bruise on the head was incidentally found to have marked intracranial calcification and a full set of false teeth. From her history of past pregnancy, it was revealed that she suffered from symptoms of hypocalcemia during late gestation (serum total Ca level, 4.8-6.4 mg/dl), which disappeared spontaneously after delivery. When the woman was not pregnant, although only the total Ca level was slightly below the normal range (7.7-8.4 mg/dl), the serum ionized Ca, phosphorus (P), magnesium, 1,25-dihydroxycholecalciferol and 24,25-hydroxycholecalciferol levels, plasma parathyroid hormone (PTH) level and urinary excretion of Ca were all normal without treatment. Intravenous infusion of 30 mg/kg EDTA-2Na resulted in marked elevation of plasma PTH associated with significant reduction of serum ionized Ca. In contrast, although her urinary excretion of phosphorous per hour was within the normal range in the basal state, she showed no proportional change in urinary phosphorous excretion with increase in urine cyclic AMP induced by administration of PTH(1-34). From these findings, she was diagnosed as having an incomplete form of pseudohypoparathyroidism Type II. This abnormality seems to be rare, but we consider that the present observations provide important information for preventive care of pregnant women and fetuses during gestation.