FHH

autosomal dominant inactivating mutation in the CaSR gene → decreased sensitivity of G-coupled calcium-sensing receptors in parathyroid glands and kidneys → higher levels of Ca2+ required to suppress PTH and higher reabsorption of Ca2+ in the kidney → hypocalciuria with mild hypercalcemia and normal or increased PTH levels

Usually asymptomatic (incidental finding)

Neonatal hypocalcemia in children of mothers with FHH (e.g., paresthesias, muscle spasms, seizures)

Hypercalcemia and inappropriately normal or increased PTH

Hypocalciuria

• ↓ 24-hour urinary calcium excretion (< 200 mg/ day)

• ↓ Urine Ca/Cr clearance ratio (< 0.02)

• See also “Assessment of urinary calcium excretion.”

Confirmatory genetic testing for CaSR gene mutations

No treatment necessary

Cinacalcet may be considered in patients with symptomatic FHH