What causes familial Hypocalciuric hypercalcemia?
Familial hypocalciuric hypercalcemia (FHH) is a rare autosomal dominant condition. It occurs as a result of mutations in the calcium-sensing receptor gene (CASR) causing decreased receptor activity.
What is hypocalciuric hypercalcemia?
Familial hypocalciuric hypercalcemia (FHH) is an inherited disorder that causes abnormally high levels of calcium in the blood (hypercalcemia) and low to moderate levels of calcium in urine (hypocalciuric). People with FHH usually do not have any symptoms and are often diagnosed by chance during routine bloodwork.
How is familial Hypocalciuric hypercalcemia treated?
As FHH is usually asymptomatic, treatment is not necessary. The hypercalcemia seen in FHH does not respond to diuretics or bisphosphonates. For those with constantly elevated serum calcium concentrations >14mg/dL or in those with NSHPT or relapsing pancreatitis, a total parathyroidectomy can be beneficial.
Is FHH an autoimmune disease?
The autoimmune form of FHH is not known to be caused by changes in a specific gene. Diagnosis of FHH is suspected by high levels of calcium in the blood, especially when there are no other symptoms present. Further blood and urine tests may be used to rule out other possible causes.
What does hypocalciuric mean?
Hypocalciuria is a low level of calcium in the urine. It is a significant risk factor for predicting eclampsia in pregnancy. The most common causes for hypocalciuria is either thiazide diuretics or reduced dietary intake of calcium. The other cause is Familial hypocalciuric hypercalcemia (FHH).
Is FHH life threatening?
Purpose of review: Hypercalcaemia is a potentially life-threatening condition. Familial hypocalciuric hypercalcaemia (FHH) is a rare, lifelong, benign condition. It is important to separate this condition from other hypercalcaemic states such as hypercalcaemia of malignancy and primary hyperparathyroidism (PHPT).
How can you distinguish between primary hyperparathyroidism and FHH?
The parathyroid hormone level is usually within the reference range or is mildly elevated. It can be distinguished from primary hyperparathyroidism by low 24-hour urinary calcium excretion. Persons with FHH are asymptomatic. Parathyroidectomy is not indicated.
How common is FHH?
Familial hypocalciuric hypercalcemia (FHH) is a very rare genetic condition that causes high blood calcium levels. It likely does not cause symptoms, and does not need to be treated. But be careful! Most of the time, high blood calcium is due to parathyroid disease, not FHH.
Does FHH cause low vitamin D?
FHH, which is also a cause of hypercalcemia, occurs less commonly. It is important to differentiate FHH from mild PHPT with concomitant vitamin D deficiency as both conditions have elevated serum PTH and calcium levels as well as normal or low 24-hour urinary calcium excretion.