Chapter 61 - Familial Benign Hypocalciuric Hypercalcemia and Neonatal Primary Hyperparathyroidism

Abstract

This chapter deals with the familial benign hypocalciuric hypercalcemia (FBHH) disorder and neonatal primary hyperparatyroidism. Study of the FBHH syndrome has led to fascinating, important advances in the understanding of the regulation of systemic calcium metabolism. FBHH, though uncommon, is globally distributed hypercalcemic syndrome is inherited in an autosomal dominant fashion and is usually characterized by lifelong asymptomatic hypercalcemia, relative hypocalciuria, and absence of classical complications of hypercalcemia, including bone disease and renal stone disease. Neonatal primary hyperparathyroidism can be a mild syndrome representing the neonatal expression of FBHH, or it can present as a much more dramatic disease with high morbidity and even mortality if untreated, a syndrome known as neonatal severe primary hyperparathyroidism (NSHPT). Furthermore, it is possible that in some cases the gestation of an FBHH fetus in an unaffected mother induces secondary hyperparathyroidism in the former because of exposure of the fetal parathyroid gland to the relative hypocalcemia of the maternal-fetal circulation. When the physician suspects FBHH in an individual patient, current knowledge permits only presumptive nongenetic diagnosis of the syndrome, but continuing research may soon lead to DNA based screening studies not only for diagnosis of the FBHH syndrome, but also for determining the specific molecular basis, in individual patients. The goal of avoiding needless surgery in FBHH would then be achievable.