Familial Hypocalciuric Hypercalcemia and Neonatal Severe Hyperparathyroidism.

Familial hypocalciuric hypercalcemia (FHH) and neonatal severe hyperparathyroidism (NSHPT) are genetically determined variants of primary hyperparathyroidism. FHH usually has a benign course, and patients do not require treatment, whereas NSHPT is a severe disorder often requiring early parathyroidectomy for young patients to survive. Recent discoveries in the genetic basis and new findings in therapeutic approaches have led to a great interest in these rare diseases.