Hereditary Hypomagnesemia
Hereditary Hypomagnesemia
Also known as:Familial hypomagnesemia, Primary hypomagnesemia, Hereditary magnesium metabolism disorder
Hereditary hypomagnesemia is a group of genetic disorders affecting magnesium absorption in the intestines or retention in the kidneys, which can lead to various presentations including low magnesium, low calcium, seizures, heart rhythm risks, or kidney calcification.
Start Here
A quick guide to the next step: which department to start with, what to prepare, and what to ask.
For recurrent low magnesium, low calcium seizures, tetany, heart rhythm abnormalities, kidney stones/kidney calcification, or unexplained low potassium and magnesium, evaluation by nephrology, pediatric nephrology, genetics/metabolism, or emergency department is appropriate.
This is not a single disease but a group of inherited magnesium transport disorders. The problem may occur in intestinal absorption, renal tubule reabsorption, or may simultaneously affect calcium, potassium, kidneys, and the nervous system.
Long-term magnesium supplementation, management of related electrolyte abnormalities, and kidney/heart rhythm follow-up plans exist, but specific goals and medication forms need to be individualized based on type and kidney function.
Yes, inheritance varies by type and may be autosomal recessive or dominant. TRPM6, CLDN16, CLDN19, CNNM2 and others may be involved.
Seizures may first be treated as epilepsy or calcium deficiency, with low magnesium only briefly corrected; if urine magnesium, kidney calcification, and family history are not checked, the hereditary cause is easily missed.
This page helps patients and families organize care leads. It does not replace a clinician’s diagnosis or treatment plan. For testing, medication, referrals, emergency care, and support applications, follow qualified clinicians, medical institutions, support organizations, and official sources.
Diagnosis Path
Organized around the practical patient journey: identify clues, avoid common delays, then prepare for care.
When to Suspect It
- Infants or young children with low magnesium accompanied by low calcium, seizures, tetany, or feeding/growth problems.
- Recurrent low magnesium, low potassium, palpitations, abnormal QT interval, or muscle cramps.
- Children or young adults with kidney stones, kidney calcification, or abnormal kidney function accompanied by low magnesium.
- Persistently low blood magnesium that repeatedly drops despite supplementation, especially if urine magnesium excretion is inappropriately elevated.
- Family history of low magnesium, seizures, kidney calcification, early-onset kidney disease, or consanguinity.
Common Wrong Turns
- Only treating with calcium or antiepileptic drugs without recognizing that low magnesium is the upstream problem.
- Attributing low magnesium to poor diet without distinguishing between gastrointestinal losses and kidney-related losses.
- Not performing kidney ultrasound or urine calcium/magnesium assessment, missing types associated with kidney calcification.
- Long-term self-supplementation without monitoring kidney function, electrolytes, or ECG.
Departments to Start With
- Nephrology
- Pediatric Nephrology
- Genetics/Medical Genetics
- Emergency (for seizures or heart rhythm risk)
- Cardiology (for ECG abnormalities)
Before the Visit
- Document results of multiple blood magnesium, calcium, potassium, creatinine, parathyroid hormone, and urine electrolyte tests.
- Record seizures, tetany, palpitations, kidney stones, kidney calcification, and family history.
- Ask whether 24-hour urine magnesium or fractional magnesium excretion assessment is needed.
- Ask whether a low magnesium-related gene panel or exome testing is needed.
- Confirm long-term supplementation, follow-up, and acute low magnesium management pathways.
Tests to Ask About
- Blood magnesium, calcium, potassium, phosphorus, creatinine, and acid-base status.
- Urine magnesium, calcium, potassium, and assessment of kidney-related losses.
- Parathyroid hormone and vitamin D-related tests.
- ECG and Holter monitoring if needed.
- Kidney ultrasound and relevant genetic testing.
Questions for the Doctor
- Is the low magnesium more likely from intestinal absorption problems or kidney wasting?
- Should I be tested for specific types of hereditary hypomagnesemia?
- How should my magnesium supplementation goals, follow-up frequency, and kidney function monitoring be arranged?
- Which symptoms indicate seizure or heart rhythm risk and require emergency care?
- Should family members be screened for blood magnesium, urine magnesium, or genetic testing?
Basic Information
Medical Notes
More complete medical explanations are kept here for discussion with clinicians.
Symptoms
Hereditary hypomagnesemia can present as low calcium seizures, tetany, muscle cramps, fatigue, palpitations, or ECG abnormalities in infancy. It may also include low potassium, kidney stones, kidney calcification, impaired kidney function, growth and developmental problems, or neurological involvement. Presentations and risks vary by genetic type.
Diagnosis
Diagnosis requires confirming persistent low magnesium and distinguishing between inadequate intestinal absorption and kidney-related magnesium loss. Evaluation typically includes blood and urine electrolytes, kidney function, urine calcium and magnesium, ECG, kidney imaging, and genetic testing. Doctors will also rule out medication effects, diarrhea, malnutrition, diabetes, and other acquired causes of low magnesium.
Treatment
Management includes correcting low magnesium and related low calcium/low potassium, monitoring heart rhythm and kidney function, managing kidney calcification or kidney stone risk, and developing a long-term supplementation plan based on the specific type. Supplementation method and dose should be adjusted by a doctor based on age, symptoms, kidney function, and tolerance.
Long-term Care
Long-term care focuses on stabilizing electrolytes, protecting kidney function, preventing seizures and heart rhythm risks, and keeping gene and emergency information on hand. Children also need monitoring of growth and development, neurodevelopment, and school care plans.
Fertility and Family
Inheritance patterns vary by gene. After identifying the disease-causing gene, families can learn about carrier testing, relative screening, prenatal diagnosis, or preimplantation genetic testing options through genetic counseling.
When to Seek Urgent Care
Seizures, altered consciousness, severe tetany, obvious palpitations or fainting, persistent vomiting or diarrhea, or rapid worsening of low magnesium and calcium require emergency care. Inform them of the hereditary hypomagnesemia risk.
Prognosis
Prognosis depends on the specific genetic type, magnesium control, kidney involvement, and early recognition of acute risks.