Clinical Characteristics of Hypoparathyroidism and Pseudohypoparathyroidism

Lee, Jung Hun; Chae, Hyun Wook; Kwon, Ah Reum; Kim, Duk Hee; Kim, Ho Seong

Abstract

PURPOSE
Insufficient production of the parathyroid hormone (PTH) by the parathyroid glands known as hypoparathyroidism, or a resistance against its action on target organs known as pseudohypoparathyroidism, cause PTH-related hypocalcemia associated with hyperphosphatemia. Signs and symptoms are caused by hypocalcemia. This study aimed to assess clinical characteristics, treatment, severity, onset time, and therapeutic responses of hypoparathyroidism and pseudohypoparathyroidism.
METHODS
From January 2000 to February 2010, 21 hypoparathyroid and 10 pseudohypoparathyroid children were selected from Severance Hospital. Clinical manifestations and laboratory data were analyzed retrospectively.
RESULTS
In hypoparathyroid patients, there were 14 with idiopathic hypothyroidism (66%) and 7 with 22q11.2 deletion syndrome (33%). Patients with hypoparathyroidism had more frequent neurologic symptoms compared to those with pseudohypoparathyroidism (2.89 +/- 1.75 vs. 1.25 +/- 1.67, P = 0.01). Required amounts of calcium to control hypocalcemia were larger in hypoparathyroidism than in pseudohypoparathyroidism (37.98 +/- 26.64 vs. 15.64 +/- 7.87 mg/day/kg, P = 0.034). After treatment, neurologic symptoms decreased significantly in hypoparathyroidism (P < 0.05) from 2.01 +/- 1.68 to 0.89 +/- 0.96.
CONCLUSION
Hypoparathyroidism presented more severe symptoms than pseudohypoparathyroidism. Larger amounts of calcium were required to correct hypocalcemia in hypoparathyroidism than in pseudophypoparathyroidsm. These differences may be explained by the findings that distal tubules respond to PTH, in contrast to proximal tubules, in pseudohypoparathyroidism, because the GNAS gene coding is not imprinted at the distal tubular cells responsible for calcium reabsorption.