Familial hypocalciuric hypercalcemia: grey zones of the differential diagnosis from primary hyperparathyroidism: a case report

Abstract

Familial hypocalciuric hypercalcemia (FHH) is an autosomal dominant inherited disorder due to inactivating mutations in the calcium-sensing receptor (CaSR), less commonly in the G-protein subunit α11 (GNA11) or the adaptor-related protein complex 2, sigma 1 subunit (AP2S1) genes. It is characterized by mild to moderate hypercalcemia, hypocalciuria, and inappropriately normal or high PTH levels. The disorder is usually asymptomatic, and bone or renal involvement is rare. Adequate differential diagnosis between primary hyperparathyroidism and FHH is important to avoid unnecessary surgery. We report the case of a male patient with FHH showing biochemical heterogeneity to highlight the difficulties of differential diagnosis

Keywords

• hypercalcemia
• familial hypocalciuric hypercalcemia
• primary hyperparathyroidism
• calcium-sensing receptor (casr)
• parathyroid