When Unexplained Hypoparathyroidism Has an Answer

What Unexplained Hypoparathyroidism Really Means

Most hypoparathyroidism follows neck surgery, when the parathyroid glands are damaged or removed. If there's no surgical cause, doctors call hypoparathyroidism non-surgical. They might also use the term "idiopathic". Idiopathic hypoparathyroidism accounts for roughly 1 in 10 hypoparathyroidism cases. Idiopathic does not mean there isn't a cause, it just means that your doctors may not have figured it out yet.

Why the Label Can Stick for Years

With surgical hypoparathyroidism, symptoms usually start suddenly. Idiopathic hypoparathyroidism symptoms often start out mild and come on gradually. People can live with these symptoms for years before getting a firm diagnosis. Autosomal Dominant Hypocalcemia Type 1 (ADH1) is the most common genetic form of nonsurgical hypoparathyroidism, and a recent survey showed that 93% of individuals diagnosed with ADH1 had first been diagnosed with idiopathic hypoparathyroidism or hypocalcemia. Many people with ADH1 are not diagnosed until their mid or late 20s – decades after symptoms may have started.

The Genetic Explanation Behind Many "Idiopathic" Cases

ADH1 is caused by a variant in the CASR gene. The CASR gene contains instructions for your body to make a calcium-sensing protein that tells your parathyroid glands and kidneys how to respond to the amount of calcium in your blood. In ADH1, the variant CASR gene tells the body how to build a protein that always tells the body there is too much calcium – even when calcium is normal or low. ADH1 is usually inherited, so first-degree relatives (parents, siblings, and children) may be worth testing too, even if they aren’t experiencing symptoms.

Why Getting Past "Idiopathic" Can Matter

If ADH1 is behind your idiopathic hypoparathyroidism, genetic testing can confirm the diagnosis. This matters because the conventional treatments for hypoparathyroidism, calcium and active vitamin D, don’t address the root cause and can lead to kidney complications over time.

Questions Worth Bringing to Your Doctor

• Has my hypoparathyroidism ever been genetically tested, or is it still labeled "idiopathic"?
• Could a genetic diagnosis change how I'm monitored or treated?
• If my hypoparathyroidism is genetic, what are the next steps for me and my family?

You're Not Alone in This

An "idiopathic" label can feel like a dead end, but it's really an open question. If your hypoparathyroidism has never been fully explained, AmbitCare may be able to help. Fill out our short questionnaire to be matched with an Ambit Guide — a real person who can connect you with no-cost genetic counseling and support as you continue to explore your diagnosis with your care team.

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.

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.