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Living with Primary hypomagnesemia

An inherited kidney condition in which the kidneys lose magnesium, leading to urinary infections, kidney stones and calcium deposits in the kidneys.

Understanding Primary hypomagnesemia

Primary hypomagnesemia (FHHN) is an inherited condition in which the kidneys waste magnesium and calcium and calcium collects in the kidneys.

It features repeated urinary tract infections, kidney stones, calcium deposits in both kidneys (nephrocalcinosis), too much calcium in the urine and kidney failure. It usually starts in childhood. Other signs can include slow growth, short stature and weak tooth enamel.

Signs & symptoms

Symptoms vary from person to person. GARD lists these among the most common:

  • Repeated urinary tract infections
  • Calcium deposits in the kidneys
  • Increased urine and extreme thirst
  • Stomach pain and vomiting
  • Short stature and poor weight gain
  • Weak tooth enamel

Not everyone has every symptom. GARD's list comes from the Human Phenotype Ontology.

Diagnosis

  1. Talk with your doctor

    Share the symptoms you've noticed, when they started and your family health history. Notes and photos can help.

  2. See a specialist

    Specialists who may be involved include genetic specialists and kidney specialists.

  3. Consider genetic testing

    Changes in CLDN16 are linked to this condition. Genetic testing and counseling can help confirm a diagnosis and explain what it means for your family.

Care & treatment

Care team
Genetic specialists (geneticists); Kidney specialists (nephrologists)
Expert care
Ask about multidisciplinary care centers for rare conditions
Treatment
GARD doesn't list specific treatments for this condition. Your care team will tailor care to your symptoms.
Research
Clinical trials and observational studies may be options. See the research section below.

General information, not medical advice. Your care team makes the decisions.

Everyday life

Living with a rare condition is easier with support.

  • Connect with National Kidney Foundation and other patient organizations
  • Keep notes on symptoms, changes and questions for appointments
  • Ask about patient registries that help research
  • Look into financial aid and travel resources for care visits
Bring these questions to your next doctor visit
Should we have genetic testing for CLDN16, and should siblings be tested?
How often should magnesium, calcium and kidney function be checked?
Which specialists, such as a kidney doctor and dentist, should be involved?

Quick facts

Symptoms usually startChild
InheritanceAutosomal Recessive
GenesCLDN16

Changes in the CLDN16 gene cause this condition. It is autosomal recessive, meaning a child inherits a changed copy of the gene from each parent.

GeneticKidneyInherited Metabolic

Also known as: cldn16 familial primary hypomagnesemia; cldn16 primary hypomagnesemia; familial primary hypomagnesemia caused by mutation in cldn16; familial primary hypomagnesemia with hypercalciuria and nephrocalcinosis without severe ocular involvement; fhhnc without severe ocular involvement; homg3

Patient organizations

Source: NIH GARD · Primary hypomagnesemiaGARD ID 2906 · GARD page updated September 2026 · Plain-language summary by Know Rare; editorial review pending. General information, not medical advice.

You are more than your diagnosis

Perspectives from people navigating life with Primary hypomagnesemia.

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Explore actively recruiting Primary hypomagnesemia studies with HealthSpark.

HealthSpark

Find actively recruiting studies for Primary hypomagnesemia with HealthSpark. Share your city to explore research near you.

  • Recruiting studies from ClinicalTrials.gov
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  • Eligibility is confirmed by the study team

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Powered by HealthSpark, our AI chat helper · Study information from ClinicalTrials.gov · Eligibility is confirmed by the study team.

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