FHH is often diagnosed in asymptomatic hypercalcemic patients with a family history of hypercalcemia, normal serum PTH levels, and very low urinary calcium excretion (<100 mg/24 hours), with a calcium-to-creatinine clearance ratio (Ca/Cr) typically less than 0.01. Here, PTH is linked to familial hypocalciuric hypercalcemia.