Does Hypoparathyroidism Run in Families?

What Causes Hypoparathyroidism?

Hypoparathyroidism happens when your parathyroid glands don't make enough parathyroid hormone (PTH), leading to low blood calcium. Most cases come from damage to the parathyroid glands during neck surgery. Surgery explains roughly three out of every four cases; the rest are linked to genetic, autoimmune, or unexplained causes. When your hypoparathyroidism isn't tied to surgery, a genetic cause may be part of the picture.

Is Hypoparathyroidism Hereditary?

For some people, yes. The most common genetic cause of nonsurgical hypoparathyroidism is Autosomal Dominant Hypocalcemia Type 1 (ADH1), caused by a variant in the CASR gene — thought to explain more than one in five cases, with an estimated 13,000 people affected in the US. ADH1 is inherited in an autosomal dominant pattern: a parent who carries the variant has roughly a 50% chance of passing it to each child, and a diagnosis can be confirmed through genetic testing. That said, ADH1 doesn't always trace back to a parent — it can also appear for the first time with no family history at all.

Family Members May Be Affected Without Knowing It

Because this inheritance pattern shows up clearly across generations, roughly half of your first-degree relatives — parents, siblings, children — may also carry the same variant, often with mild, easy-to-miss signs like slightly low calcium or a lower-than-expected PTH level. A parent or sibling may only learn they've had unrecognized hypoparathyroidism for years after a child is diagnosed. Because symptoms can be so mild, a real gap can exist between how many people likely carry the variant and how many have been formally diagnosed.

When It's Worth Asking About Genetics

Genetic testing is generally worth discussing for nonsurgical hypoparathyroidism when there's a family history, other syndromic features, or a patient is younger than 40 years. Testing can guide your treatment and flag family members who may want to be tested — even without symptoms.

You Don't Have to Piece This Together Alone

Wondering whether hypoparathyroidism runs in your family can raise more questions than answers, especially if no one has explained the cause behind a diagnosis. A few things worth asking your doctor:

• Has a cause for my hypoparathyroidism ever been confirmed, or is it still labeled "idiopathic"?
• Could genetic testing help explain it, or identify family members who might also be affected?
• Has anyone else in my family had calcium problems, kidney stones, or unexplained seizures?

You don't have to sort through it alone. If you or a family member has hypoparathyroidism without a clear surgical cause, AmbitCare can help. Fill out our short questionnaire to connect with an Ambit Guide — a real person who can help you explore genetic counseling and next steps with your care team.

In Partnership with BridgeBio Ambit is offering support and educational resources on behalf of BridgeBio, a pharmaceutical company that researches and manufactures treatments for rare diseases like hypoparathyroidism and ADH1.

Please note that AmbitCare provides this information for the benefit of the rare disease community. AmbitCare is not a medical provider nor a health care facility. AmbitCare can neither diagnose any disease or disorder nor endorse or recommend any specific medical treatments. Individuals must rely on the personal and individualized medical advice of their qualified health care professionals before seeking any information related to their particular diagnosis, cure, or treatment of a condition or disorder.