Familial Hypocalciuric Hypercalcemia: What You Need To Know and Possible Treatments


Are you facing bone loss, kidney stones, and an increased risk of cardiovascular events? If you are, you could be suffering from Familial Hypocalciuric Hypercalcemia (FHH), also known as Familial Benign Hypocalcemia.

According to research, a person with FHH has a 50 percent risk of passing on the genetic change (pathogenic variant, also called a mutation) to each of their children.

The following guide will explain what FHH is and how it works. It will offer an insight into the treatments available for those suffering from this disorder.

1) What is  Familial Hypocalciuric Hypercalcemia?

FHH is a condition that causes too much calcium to be absorbed from the diet. Specific individuals who have this condition can lead to increased bone density and kidney stones. It may also cause an increase in cardiovascular risks even though one’s blood calcium level does not change; this is because the calcium in the blood is being deposited in bones and soft tissues.

2) What Are The Symptoms Of FHH?

FHH has some common symptoms. These are explained in detail here.

1) Bone Loss

Bone loss means the bones are becoming more brittle and fragile. Usually, those suffering from FHH notice an increase in bone fractures as they grow older. Some studies show that adults with FHH have twice as many recurrent fractures as those who do not have the disorder.

2) Kidney Stones

Kidney stones occur when minerals concentrate inside the kidneys to form a hard mass. In many cases, stones are too small to feel and do not cause pain. Larger kidney stones get stuck in the urinary tract and block urine from passing out the kidneys. It can be excruciating.

3) Increased Risk for Cardiovascular Disease

Familial hypocalciuric hypercalcemia has been associated with an increased risk for cardiovascular disease. The trouble is thought to be related to calcium deposits in the inner layers of artery walls.

4) Bone Pain due to Multiple Myeloma or Mastocytosis

Bone pain can result from multiple myeloma (a disease where plasma cells become abnormal and divide uncontrollably, leading to bone fractures). It can also occur because of mastocytosis (a rare condition in which specific white blood cells become malignant).

3) Why does FHH occur?

A change or mutation causes FHH to the calcium-sensing receptor gene. The receptor is located on chromosome 11p. This sensor sits in the cell wall that measures how much calcium is present outside the cell. Information from this receptor is transmitted to the cell’s nucleus then used to control normal calcium levels in the bloodstream.

FHH happens when a mutation makes the sensor unable to respond to calcium levels in the blood. As a result, people with FHH will absorb too much calcium – even while taking prescribed medication to lower their calcium levels.

4) Genetic Testing for FHH

To determine if someone has FHH, a calcium test would be conducted. The serum calcium test measures the amount of calcium in one’s blood at any given time. The ionized calcium test is similar, but it explicitly tests how much calcium binds to the protein albumin.

This protein carries calcium in the blood, so too much free (unbound) calcium could circulate in the bloodstream if the ionized calcium is too high.

If either of these tests shows that serum or ionized calcium levels are very high (above 10.0 mg/dL), then FHH may be the cause. Genetic testing for FHH is usually undertaken only if the cause of the hypercalcemia cannot be determined through serum or ionized calcium tests.

5) How do you treat FHH?

FHH can be easily treated with medication that increases how much calcium leaves the bloodstream. It does so by inhibiting parathyroid hormone (PTH) production, which blocks calcium release from the bones.

Different types of medication can be prescribed for FHH depending on how old someone is when they are diagnosed with the disorder. Here’s a helpful guide to how one might treat people who suffer from FHH:

1) People Who Are Younger Than 16 Years Old

People who are younger than 16 years old take the medication cinacalcet. The drug inhibits PTH production and is taken once a day with food. Additionally, doctors may prescribe phosphate supplements to prevent shadows on X-rays that indicate bone loss.

2) People Who Are Between 16 And 30 Years Old

If someone is between 16 and 30 when diagnosed with FHH, treatment is the same as for younger folk (cinacalcet and phosphate supplements). However, this person may also receive bisphosphonate medication. This drug inhibits osteoclast production, ensuring that more calcium is being removed from the bones.

3) People Who Are Older Than 30

If someone is older than 30, cinacalcet and phosphate supplements are still likely to be prescribed. However, this person would not receive bisphosphonate medication.

These are some of the treatment options for people suffering from FHH.


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