Other
Homocysteine
Also known as: Hcy
CONVERT & COMPARE
µmol/L
=
7.9
umol/L
=
7.9
mcmol/L
Reference ranges by source
Published adult intervals: 143, from 3 named sources, shown in µmol/L.
SOURCE
SEX
AGE
RANGE
VISUAL
CITE
Ages 0–17 (CALIPER)
34 age- and sex-stratified entries from the Canadian Laboratory Initiative on Pediatric Reference Intervals.
SOURCE
SEX
AGE
RANGE
VISUAL
CITE
About Homocysteine
A homocysteine test measures the amount of homocysteine in a sample of your blood. Homocysteine is an amino acid. Amino acids are molecules that your body uses to make proteins.
Normally, your homocysteine levels are low. That's because your body uses vitamin B12, vitamin B6, and folic acid (also called folate or vitamin B9) to quickly break down homocysteine and change it into other substances that your body needs. High levels of homocysteine in your blood may be a sign that this process isn't working right or that you're lacking certain B vitamins. Because of this link, homocysteine is sometimes checked alongside another marker called methylmalonic acid (MMA) to help diagnose vitamin B12 or folate deficiency, especially when red blood cells appear larger than usual on a blood count.
If homocysteine isn't broken down, it can build up in your blood and may damage the lining of your arteries (the blood vessels that carry oxygen-rich blood from your heart to the rest of your body). Higher homocysteine levels are linked to higher rates of heart and blood vessel disease in some studies, but large clinical trials have shown that lowering homocysteine with B-vitamin supplements does not reduce heart attacks, strokes, or deaths. Because of this, current heart disease guidelines do not recommend routine homocysteine testing to estimate cardiovascular risk in most people.
Main source: MedlinePlus ↗
Useful for
Help diagnose homocystinuria. Homocystinuria is a rare, genetic disease that prevents your body from making an enzyme that helps to break down homocysteine. An enzyme is a protein that speeds up certain chemical reactions in your body. Symptoms usually show up in the first year of life, but they may not appear until childhood or later. Common symptoms include problems with eyesight, blood clots, and weak bones. In the U.S., most newborns have a routine screening test to check for homocystinuria.
Better understand your risk for heart attack or stroke if you already have an increased risk. Your health care provider may order a homocysteine test if you have been diagnosed with heart or blood vessel disease or if you have conditions that increase your risk for heart and blood vessel disease, such as high blood pressure, high cholesterol, and diabetes. A high homocysteine level on its own can act as a separate risk factor for heart and blood vessel disease.
Investigate symptoms or conditions that may be linked to high homocysteine, including anemia (a condition where you don't have enough healthy red blood cells), nerve damage throughout your body, and cognitive decline (the loss of memory, reasoning, and thinking skills over time).
Help check for vitamin B12 or folate deficiency, often along with a methylmalonic acid (MMA) test, especially when red blood cells are larger than normal (a high MCV).
Main source: MedlinePlus ↗
Interpretation
Higher than normal homocysteine levels may happen with conditions such as osteoporosis, chronic kidney disease, hypothyroidism, schizophrenia, or Alzheimer's disease or other types of dementia.
If your homocysteine levels are high, it doesn't always mean you have a medical condition that needs treatment. If you have questions about your results, talk with your provider.
For general wellness information only. Talk to a clinician about your specific results.
Main source: MedlinePlus ↗
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Related biomarkers
More tests in the other category.
Sources
Last updated 2026-05-02
This page presents source-specific reference data and sourced explanations. For general wellness information only. This is not medical advice. For diagnosis or treatment of any condition, talk to a qualified clinician.