Familial benign hypocalzuric hypercalcemia

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Classification according to ICD-10
E83.5 Disorders of calcium metabolism
Familial hypocalciuric hypercalcaemia
ICD-10 online (WHO version 2019)

The familial benign hypokalzurische hypercalcemia (FBHH) is a rare, autosomal dominant inherited disorder of the calcium -Haushalts caused by an inactivating mutation of the calcium-sensing receptor in parathyroid and kidney caused. Characteristic are increased calcium levels in the blood ( hypercalcaemia ) with reduced calcium excretion in the urine ( hypocalciuria ). The disorder is harmless and does not require treatment; its importance lies in differentiating it from forms of hypercalcemia that require treatment .

It is characterized by a family history with elevated calcium levels ( hypercalcaemia ), especially in young children, and the absence of symptoms that normally accompany elevated calcium levels (such as loss of appetite, dysfunction of nerves and muscles, or increased urine production ).

Elevated parathyroid hormone concentrations are found in around 15–20% of those affected , which can sometimes make it difficult to differentiate from primary hyperparathyroidism . The distinction is important insofar as primary hyperparathyroidism can be cured by surgical removal of the enlarged parathyroid body (s), while in familial hypocaluric hypercalcemia an operation is neither necessary nor promising.

Patients with familial hypocalcuric hypercalcaemia usually have low urinary calcium excretion ( hypocalzuria ), whereas most patients with primary hyperparathyroidism have normal or increased calcium excretion.

In contrast to primary hyperparathyroidism, those affected have no symptoms. Life expectancy is normal. Complications of the skeleton ( fractures , demineralization) or the kidneys ( calcification , kidney stones ) do not occur in familial hypocalzuric hypercalcemia.

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