A Case of Pseudohypoparathyroidism in a Premature Infant

ABSTRACT

In pseudohypoparathyroidism as reported by Albright in 1942, the parathyroid gland can normally synthesize and secrete parathyroid hormone(PTH). Pseudohypoparathyroidism has a similar biochemical finding with hypoparathyroidisms like hypocalcemia and hyperphosphatemia due to target tissue resistance to PTH. Administered PTH does not raise the serum levels of calcium and urinary phosphate. PTH activates G-protein in peripheral tissue and adenylate cyclase through a second messenger, cAMP. Pseudohypoparathyroidism produces hyperphosphatemia and hypocalcemia because of the resistance to PTH in peripheral tissue due to a defect of G-protein, although it releases PTH normally. According to the mechanism of resistance, pseudohypoparathyroidism is classified into types Ia, Ib, Ic and psedopseudohypoparathyroism. Type Ia is accompanied by congenital growth retardation and abnormal bony development that shows mental retardation, obesity, low height, round face, short metacarpal bone and metatarsal bone, ectopic calcification, etc. We report a case of pseudohypoparathyroidism in a premature who shows hypocalcemia, hyperphosphatemia, elevation of serum PTH and 24 hr urinary basal c-AMP in biochemical tests without Albright's hereditary osteodystrophy at physical examination, accompanied by a spontaneous fracture in the femur.