Overview
Primary hypomagnesemia with secondary hypocalcemia (HSH) is a rare inherited condition where the body cannot properly absorb magnesium from food in the intestines. Magnesium is a mineral that every cell in your body needs to work correctly. When magnesium levels drop too low, calcium levels also fall — this is why the condition is called 'with secondary hypocalcemia.' The disease is also sometimes called familial hypomagnesemia with secondary hypocalcemia, or simply HSH. This condition usually appears in the first weeks or months of life. Babies with HSH often have seizures, muscle spasms, and irritability because their nervous system and muscles depend heavily on magnesium and calcium to function. Without treatment, the low magnesium and calcium can cause serious and permanent brain damage. The good news is that this condition can be managed with lifelong magnesium supplements taken by mouth. When treatment is started early and maintained consistently, many children can live relatively normal lives. However, treatment must continue for life because the intestines never gain the ability to absorb magnesium normally. Regular monitoring of magnesium levels in the blood is essential to make sure the dose stays correct as the child grows.
Also known as:
Key symptoms:
Seizures in early infancyMuscle spasms or cramps (tetany)Tremors or shakingIrritability and excessive cryingFeeding difficulties in newbornsMuscle weaknessDevelopmental delay if untreatedIntellectual disability if diagnosis is delayedLow magnesium levels in the bloodLow calcium levels in the bloodAbnormal heart rhythms in severe cases
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
1 availableIMPAVIDO
treatment of visceral leishmaniasis caused by Leishmania donovani
Clinical Trials
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Specialists
View all specialists →No specialists are currently listed for Primary hypomagnesemia with secondary hypocalcemia.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Financial Resources
1 resourcesTravel Grants
No travel grants are currently matched to Primary hypomagnesemia with secondary hypocalcemia.
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Caregiver Resources
NORD Caregiver Resources
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Mental Health Support
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Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.What is the right dose of magnesium for my child right now, and how often should we adjust it as they grow?,How often do we need blood tests to check magnesium and calcium levels?,What are the warning signs that magnesium is dropping too low, and what should I do at home before going to the emergency room?,Are there any foods or medications that can interfere with magnesium absorption?,Should other family members be tested for this condition, including siblings?,What long-term effects should we watch for, and how can we protect my child's brain development?,Is there a patient registry or research study we could join to help advance understanding of this disease?
Common questions about Primary hypomagnesemia with secondary hypocalcemia
What is Primary hypomagnesemia with secondary hypocalcemia?
Primary hypomagnesemia with secondary hypocalcemia (HSH) is a rare inherited condition where the body cannot properly absorb magnesium from food in the intestines. Magnesium is a mineral that every cell in your body needs to work correctly. When magnesium levels drop too low, calcium levels also fall — this is why the condition is called 'with secondary hypocalcemia.' The disease is also sometimes called familial hypomagnesemia with secondary hypocalcemia, or simply HSH. This condition usually appears in the first weeks or months of life. Babies with HSH often have seizures, muscle spasms, an
How is Primary hypomagnesemia with secondary hypocalcemia inherited?
Primary hypomagnesemia with secondary hypocalcemia follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Primary hypomagnesemia with secondary hypocalcemia typically begin?
Typical onset of Primary hypomagnesemia with secondary hypocalcemia is neonatal. Age of onset can vary across affected individuals.