Normocalcemic Hyperparathyroidism

Abstract

Parathyroid hormone (PTH) disorders are characterized by a wide spectrum of clinical and biochemical presentations. The increasing use of serum PTH assay in the set of the diagnostic workout in patients with osteoporosis has identified patients with features of surgically confirmed primary hyperparathyroidism (PHPT) associated with persistent normal serum calcium levels, which has been recognized as a distinct entity from hypercalcemic PHPT (HPHPT) by the last international consensus. Normocalcemic PHPT (NPHPT) affects about 6-8% of PHPT patients. Although hypercalcemia is absent, patients with NPHPT experience kidney, bone, and cardiovascular impairments similar to those observed in HPHPT, suggesting that NPHPT may significantly affect the health of patients. Diagnosis of NPHPT requires an intensive diagnostic workup aimed to: (1) exclude all causes of secondary hyperparathyroidism, and (2) evaluate the occurrence of PTH-related diseases. The management of NPHPT is controversial in part due to lack of solid data about the natural history as well as the effects of surgical or medical treatments. Nonetheless, a clinical and biochemical follow-up is recommended in order to detect potential progression. When hypercalcemia and/or PTH-related disorders arise, parathyroidectomy can be considered. When surgery is not advisable, medical treatment aimed to increase bone mineral density may be a therapeutic option.