Osteitis fibrosa cystica with renal parathyroid hormone resistance: a review of pseudohypoparathyroidism with insight into calcium homeostasis.

Pseudohypoparathyroidism is a group of diseases characterized by renal resistance to parathyroid hormone. The patients typically have the bony manifestations of hyperparathyroidism, while being hypocalcemic. Pseudohypoparathyroidism has further been subdivided into types Ia, Ib, Ic, and II. Mutations involving any number of domains of the parathyroid hormone receptor, adenylate cyclase, or G proteins may alter the cellular response to parathyroid hormone. This wide range of possible sites of mutation may explain the heterogeneous biochemical, skeletal, and physical phenotypes associated with the various types of pseudohypoparathyroidism. We describe a patient with pseudohypoparathyroidism who was successfully treated with total parathyroidectomy and gland autotransplantation. The complexities of parathyroid hormone cellular interactions and calcium homeostasis are discussed. Pseudohypoparathroidism is an unusual disease; however, it provides an elegant model for studying problems of calcium balance.