Histidinemia: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 2, 2026.
What kind of doctor treats Histidinemia?
A primary care doctor, such as a family doctor or pediatrician, usually manages histidinemia by ordering follow-up tests and monitoring growth and development. If a child has developmental concerns, the doctor may refer the family to a developmental pediatrician or geneticist. A metabolic specialist may be involved in unusual cases.
What is histidinemia?
Histidinemia is a rare inherited condition in which the body has trouble breaking down an amino acid called histidine. Histidine builds up in the blood, urine, and spinal fluid. Many people with histidinemia stay healthy, and doctors often find it only during newborn screening tests.
Histidinemia is a metabolic disorder, meaning the body's chemical processes do not work properly. The enzyme histidase, which normally converts histidine into another substance the body can use, is missing or does not work well, so histidine collects in the body. Larger studies showed most people with the condition develop normally, and many researchers now consider it mostly harmless.
Symptoms
Most people with histidinemia have no symptoms at all. The condition is usually discovered by chance on a newborn blood test. When symptoms do appear, they can include speech delays or mild learning difficulties.
Causes and who gets it
Histidinemia is genetic and follows an autosomal recessive pattern, meaning a child must receive one changed copy of the HAL gene from each parent. Parents who carry only one changed copy usually have no symptoms. It is rare, affecting roughly one in several thousand babies in some regions, with higher rates reported in Japan.
How doctors diagnose it
Many babies are tested shortly after birth through newborn screening. If the test shows high histidine, doctors may measure histidine levels in blood and urine, and genetic testing can confirm the diagnosis. Doctors also rule out other causes of high histidine, such as liver problems.
Treatment
Most people with histidinemia do not need any treatment. Doctors often simply monitor the person over time. Low histidine diets are generally not advised today, and children with speech delays may be referred for speech therapy or other support services.
When to see a doctor
If a newborn screening test shows high histidine levels, follow up with the baby's doctor promptly to confirm the finding. Parents should also talk to a doctor if a child has unexplained speech delays or developmental concerns. Anyone planning a pregnancy with a family history of the condition may want to ask about genetic counseling.
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 be a good fit for this kind of ongoing monitoring, offering longer appointments and easier access between visits. They can manage routine follow-up and refer to specialists when needed.
Common questions
Is histidinemia dangerous?
For most people, histidinemia does not cause any health problems. Many doctors now view it as a harmless difference in body chemistry. A small number of people may have speech or learning issues, so regular checkups are helpful.
Can histidinemia go away?
Histidinemia is a genetic condition, so it does not go away. However, it usually does not need treatment, and people with it typically live normal, healthy lives.
Do I need a special diet if I have histidinemia?
Most doctors no longer recommend special diets for histidinemia. Current practice usually involves simple monitoring. Always ask a doctor before changing a diet.
Sources
- NIH Genetic and Rare Diseases Information Center - Histidinemia
- MedlinePlus Genetics - Histidinemia
- MedlinePlus - Newborn Screening
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.
