PTH and hypercalcemia disease: FHH3 has an estimated prevalence of 7.8 per 100,000,(154) and is associated with more severe hypercalcemia than FHH1.(155, 156) FHH3 patients may also have low bone mineral density (BMD), osteomalacia, or neurodevelopmental disorders.(155, 157) Because the underlying genetic abnormality in FHH directly causes alteration in the calcium‐PTH setpoint in all parathyroid cells, surgical excision of parathyroid glands is generally inadvisable and will typically result in persistent hypercalcemia or, if total parathyroidectomy is performed, in the adverse outcome of hypoparathyroidism.