454 INCREASING SERUM PARATHORMONE (PTH) AND MIGRATORY SUBCUTANEOUS CALCIFICATION IN THE PROGRESSION OF PSEUDOPSEUDOHYPOPARATHYROIDISM TO PSEUDOHYPOHYPOPARATHYROIDISM

Abstract

Pseudopseudohypoparathyroidism progressing to pseudohypoparathyroidism has not been previously studied. A male sibling of a child with pseudohypoparathyroidism was studied for 2 yrs. At 1 yr he had generalized subcutaneous calcifications which were “migratory”, was round faced, slightly obese, with stubby fingers and dimples on the dorsa of his hands. Serum Ca was 9-9.5 mg/dl for the 1st 18 mos and then fell to 8.9, 8.6, 8.3 mgm/dl over 6 mos. Serum P was 5.7-6.2 mgm/dl for 18 mos and rose to 6.4, 6.8 and 7.6 mgm/dl over 6 mos. Serum PTH rose from 54μlEq/ml (N <57) to 89, 117, 312, 735 and 750μlEq/ml over 6 mos. 1,25 Dihydroxy Vit. D increased from 40 to 69 pg/ml (N=17-44 pg/ml). At 3 yrs there was no calcemic, phosphaturic or urinary cAMP response to PTH. Serum PTH was suppressed by Ca infusion and doubled with EDTA infusion indicating that the parathyroids were sensitive to Ca changes. On x-ray, enlarged cranium, thickened diploe, broad and short 1st and 4th metacarpals were seen. Auto immune antibodies were absent. Serum T4 was 7.2mg/dl (low N) and TSH was elevated 17.6μU/ml. Prolactin and cortisol were N. Thus, increasing PTH levels presage overt pseudohypoparathyroidism and may indicate preclinical disease. We speculate that increasing serum PTH reflects increasing compensatory parathyroid production to overcome the PTH receptor defect and serves in the early stage of the disease to maintain normocalcemia.