Hypermethioninemia: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 2, 2026.
What kind of doctor treats Hypermethioninemia?
A primary care doctor usually manages day to day care, and most patients also see a metabolic specialist. A dietitian can help plan meals. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is hypermethioninemia?
Hypermethioninemia is a condition in which the blood has too much of an amino acid called methionine. Amino acids are the building blocks of protein, and they come from the food you eat. Some people have a mild form and feel fine. Others have a more serious form that needs lifelong care.
Methionine comes from protein foods such as meat, fish, eggs, and dairy. When the body cannot break it down properly, it builds up in the blood. Doctors usually find it through newborn screening.
Symptoms
Many people with the mild form have no symptoms. Babies with a serious inherited form may have delays in milestones, unusual sleepiness, poor feeding, or a smell of boiled cabbage in sweat or urine. Some develop liver problems.
Causes and who gets it
The most common cause is a change in a gene called MAT1A, inherited from both parents. Other causes include liver disease, a very high protein diet, or homocystinuria, a related inherited condition.
How doctors diagnose it
Most cases are found through newborn screening, a heel prick blood test in the first days of life. If the result is high, the doctor orders more blood and urine tests to confirm the cause.
Treatment
Treatment depends on the cause and how high the level is. Mild cases often need only regular blood tests. Others may need less protein or a special medical formula. Treatment can usually keep levels in a safer range.
When to see a doctor
If a newborn screening test came back abnormal, contact your baby's doctor right away, even if the baby looks healthy. Call a doctor for poor feeding, extreme sleepiness, developmental delays, or a strong unusual smell. Adults with high methionine should follow up.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Either can order blood tests, track methionine levels, and coordinate care with a dietitian and specialist.
Common questions
Is hypermethioninemia the same as homocystinuria?
No. Homocystinuria is a related inherited condition where the body also builds up a substance called homocysteine. It tends to cause more serious problems. Hypermethioninemia can happen on its own or as part of homocystinuria, so doctors run extra tests to tell them apart.
Can adults find out they have this condition?
Yes, though it is less common. Some adults learn about it when a routine blood test shows a high methionine level. Others find out during testing for liver problems or after a relative is diagnosed.
Does my child need to stop eating protein?
Not always. Some people need a lower protein diet, while others with the mild form can eat normally. A doctor and dietitian will decide based on blood test results. Any diet change should be made with their guidance.
Will my other children have it too?
It depends on the cause and on whether both parents carry the changed gene. A genetic counselor can explain the chances and offer testing for family members. This is a common reason families meet with a counselor after a diagnosis.
Sources
- MedlinePlus Genetics - Hypermethioninemia
- NIH Genetic and Rare Diseases Information Center - Hypermethioninemia
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
