Hypocalciuric hypercalcemia, familial

Familial Hypocalciuric Hypercalcemia (FHH) is a rare, inherited disorder characterized by elevated levels of calcium in the blood (hypercalcemia) but with normal or low levels of calcium in the urine (hypocalciuria). This condition is often asymptomatic and is usually discovered incidentally through routine blood tests. FHH is caused by mutations in genes that are involved in the regulation of calcium metabolism in the body.

Causes and Genetics

FHH is most commonly caused by mutations in the CASR gene, which encodes the calcium-sensing receptor (CaSR). The CaSR plays a crucial role in maintaining calcium homeostasis in the body by regulating the release of parathyroid hormone (PTH). Mutations in the CASR gene lead to a decreased sensitivity of the calcium-sensing receptor to calcium levels in the blood, resulting in inappropriate secretion of PTH and subsequent hypercalcemia. Less commonly, mutations in the GNA11 or AP2S1 genes can also cause FHH.

Symptoms

Most individuals with FHH are asymptomatic, meaning they do not exhibit symptoms. When symptoms do occur, they are usually mild and can include fatigue, muscle weakness, and excessive thirst and urination. Severe symptoms are rare but can include kidney stones and calcification of soft tissues.

Diagnosis

Diagnosis of FHH is based on the findings of hypercalcemia with hypocalciuria. A detailed family history is also important for diagnosis, as FHH is inherited in an autosomal dominant manner, meaning that only one copy of the affected gene is needed for the disorder to be passed on. Genetic testing can confirm the diagnosis by identifying mutations in the CASR, GNA11, or AP2S1 genes.

Treatment

Treatment for FHH is usually not necessary due to the mild nature of the condition. It is important, however, to differentiate FHH from primary hyperparathyroidism, a more common condition that can present with similar symptoms but requires different management. In cases where treatment is considered, it is usually aimed at managing symptoms rather than the underlying genetic condition.

Prognosis

The prognosis for individuals with FHH is generally excellent, as the condition tends to be mild and does not typically result in serious health problems. However, individuals with FHH should be monitored for potential complications, such as kidney stones or calcification of soft tissues.

Hypocalciuric hypercalcemia, familial Resources
Latest articles Most recent articles Ongoing trials	Wikipedia