Re: Familial Hypocalciuric Hypercalcemia
mtniharika - 09-18-09 14:46

Familial hypocalciuria hypercalcemia (FHH) is an autossomal dominant condition caused by mutations in the calcium sensing receptor gene-mutation in R648X of CASR gene (located in the long arm of chromossome 3).
It is characterized by moderate hypercalcemia,
hypocalciuria secondary to the increased calcium reabsorption at DCT,
normal or slightly elevated PTH levels, and
variable hypermagnesemia.

Diagnosis of FHH:
•Hypercalcemia
•Calcium/creatinine clearance ratio <0.01
•Hypercalcemic infant/child in family
•Genetic testing for mutations in CASR

Differential diagnosis:
primary hyperthyroidism
Differentiation from primary HPT can often be achieved by measuring the renal calcium/creatinine clearance ratio, which generally is less than 0.01 in patients with FHH and higher in patients with primary HPT .Genetic testing for FHH-associated mutations in CASR can allow a diagnosis of FHH in cases where biochemical tests remain inconclusive.

treatment:
FHH does not require any treatment