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PubMed This is a summary of 54 peer-reviewed journal articles Updated
Endocrinology

Understanding Autosomal Dominant Hypocalcemia (ADH)

At a Glance

Autosomal Dominant Hypocalcemia (ADH) is a rare genetic disorder causing low blood calcium due to an overly sensitive calcium-sensing receptor. It requires genetic testing to confirm, as standard low-calcium treatments can cause severe kidney damage in people with ADH.

Navigating a diagnosis of Autosomal Dominant Hypocalcemia (ADH) can feel overwhelming, especially because it is a rare condition that even some medical professionals may not encounter frequently [1][2]. If you have spent years feeling like something was wrong or have been misdiagnosed with other conditions, your experience is valid. ADH is a genetic disorder that changes how your body “senses” and regulates calcium, leading to lower-than-normal levels in the blood [3][4].

The Role of the Calcium-Sensing Receptor

To understand ADH, it helps to think of your body’s Calcium-Sensing Receptor (CaSR) as a thermostat. In a typical body, this “thermostat” is set to maintain calcium at a specific level. When it detects that calcium is too low, it signals the parathyroid glands (four small glands in the neck) to release Parathyroid Hormone (PTH) [5][6]. This hormone then tells the body to pull calcium from the bones and stop the kidneys from flushing it out in urine.

In patients with ADH, the “thermostat” is broken. Because of a genetic mutation (a change in the DNA), the CaSR is overly sensitive or “hyper-active” [3][7]. It incorrectly senses that there is plenty of calcium in the blood, even when levels are actually dangerously low [8][9].

Why PTH Levels Drop

Because the sensor is constantly telling the body it has enough calcium, two things happen:

  1. Suppressed PTH: The parathyroid glands stop producing enough PTH because they think it isn’t needed [3][10].
  2. Renal Wasting: The kidneys, also sensing “high” calcium, work overtime to flush calcium out of the body through urine [11][10]. This is known as hypercalciuria (high calcium in the urine) [12][13].

Understanding the Two Types of ADH

Researchers have identified two primary ways this genetic “short circuit” happens:

  • ADH Type 1 (ADH1): This is caused by a mutation directly in the CASR gene, which provides the instructions for the calcium sensor itself [14][15].
  • ADH Type 2 (ADH2): This is caused by a mutation in the GNA11 gene. This gene helps send the signal from the sensor to the rest of the cell. If it is overactive, the body receives a “too much calcium” signal even if the sensor is working normally [8][16].

The Challenge of Misdiagnosis

ADH is frequently misdiagnosed as idiopathic hypoparathyroidism (low parathyroid function of unknown cause) [17][12]. This distinction is critical because the standard treatment for hypoparathyroidism—high doses of calcium and vitamin D—can actually be harmful for someone with ADH. Because the ADH “sensor” in the kidney is already trying to flush calcium, adding more calcium can lead to nephrocalcinosis (calcium deposits in the kidneys) or kidney stones [17][18].

Moving Toward a Correct Diagnosis

Current clinical standards emphasize genetic testing as the most reliable way to confirm ADH [19][20]. A diagnosis is usually suspected when a patient has:

  • Low blood calcium (hypocalcemia) [8][2].
  • Low or “inappropriately normal” PTH levels [3][1].
  • High levels of calcium in the urine relative to the low levels in the blood [12][13].

Identifying the specific genetic cause through testing allows your care team to tailor your treatment to protect your kidney health and improve your quality of life [20][21].
Diagnosis and Genetics | Symptoms and Complications | Treatment Strategy | Long-Term Monitoring

In this guide

4 chapters

01

The Genetics and Lab Markers of ADH1 and ADH2

Understand Autosomal Dominant Hypocalcemia (ADH) lab results and genetics. Learn the difference between ADH1 and ADH2, CASR vs GNA11 genes, and hypercalciuria.

02

Symptoms and Long-Term Risks of ADH

Learn about the immediate symptoms of Autosomal Dominant Hypocalcemia (ADH) and the long-term risks of treatment, including kidney and brain calcifications.

03

The Treatment Strategy: Balancing Calcium and Kidney Health

Learn about Autosomal Dominant Hypocalcemia (ADH) treatment. Discover why low-normal calcium goals protect your kidneys and explore new calcilytic therapies.

04

Your Long-Term Care and Monitoring Plan

Learn how to manage Autosomal Dominant Hypocalcemia (ADH) long-term. Discover the specialists you need, routine monitoring tests, and sick day protocols.

Common questions in this guide

What is Autosomal Dominant Hypocalcemia (ADH)?
Autosomal Dominant Hypocalcemia is a rare genetic disorder where the body's calcium-sensing receptor is overly sensitive. It mistakenly tells the body there is too much calcium, leading to low blood calcium levels and high calcium in the urine.
Why shouldn't I just take high doses of calcium and vitamin D?
Standard high-dose calcium and vitamin D treatments can be dangerous for people with ADH. Because your kidneys are already working overtime to flush out calcium, taking more can lead to kidney stones or calcium deposits in the kidneys.
How is Autosomal Dominant Hypocalcemia diagnosed?
Doctors suspect ADH when blood calcium is low, parathyroid hormone is low or normal, and urine calcium is abnormally high. A definitive diagnosis is made using genetic testing to look for mutations in the CASR or GNA11 genes.
What are the main types of ADH?
There are two primary types of ADH based on the affected gene. ADH Type 1 is caused by a genetic mutation in the CASR gene, while ADH Type 2 is caused by a mutation in the GNA11 gene. Both cause similar symptoms and issues with calcium regulation.
Why is genetic testing important for low calcium conditions?
Genetic testing confirms whether your low calcium is caused by ADH or another condition like idiopathic hypoparathyroidism. Knowing your exact genetic diagnosis helps your doctor create a safe treatment plan that protects your long-term kidney health.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Was my diagnosis confirmed through genetic testing for the CASR or GNA11 genes?
  2. 2.How do my current PTH levels and urine calcium levels compare to what you would expect in ADH?
  3. 3.Should my immediate family members (parents, siblings, children) be screened for low calcium?
  4. 4.Could a vitamin D deficiency be masking the typical 'high urine calcium' finding in my labs?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

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This page provides educational information about Autosomal Dominant Hypocalcemia (ADH) and its genetic causes. It is not intended to replace professional medical advice or personalized treatment plans from your endocrinologist or geneticist.

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