A Case of Pseudohypoparathyroidism Type I

Abstract

Pseudohypoparathyroidism (PHP) is a rare clinical type of hypoparathyroidism. The patients with PHP show classic clinical and biochemical features of hypoparathyroidism, but elevated serum level of parathyroid hormone (PTH) and characteristic physical appearances termed ‘Albright's hereditary osteodystrophy’ (AHO). PHP is classified into types Ia, Ib, Ic and II according to the presence of AHO phenotype and the mechanism of PTH resistance. We experienced a case of PHP in a 12 year-old girl with carpopedal spasm, syncope and partial AHO. She showed very low serum calcium level (1.4 mmol/L), high phosphorus level (3.62 mmol/L) and high immunoreactive PTH level (186.6 ng/L). In the Ellsworth-Howard test, urinary cyclic adenosine monophosphate and phosphorus levels after an exogenous PTH injection remained unchanged. Therefore, we were able to classify the patient as either PHP type Ia or Ic. After the patient had been treated with daily calcium carbonate (1 g), cholecalciferol (250 IU) and calcitriol (0.5 μg), her neurological signs and symptoms as well as her biochemical abnormalities of hypocalcemia and hyperphosphatemia were improved. (J Kor Soc Endocrinol 21:338~344, 2006)