Laboratory test · Cholesterol and heart health
Homocysteine
- Sample: venous blood
- Preparation: morning fasting
Test price
- Sample
- venous blood
- Preparation
- morning fasting
Paymentcash, cards and instalments
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Homocysteine is an amino acid formed in the body during breakdown of methionine, an amino acid from dietary proteins. Testing measures its blood level and most often helps when a doctor investigates vitamin B12 or folate deficiency, less commonly in thrombosis or rare inherited disorder investigations. Elevated homocysteine is associated with cardiovascular disease, but has not been proven to cause it.
Who is this test for
- people who are tired, anaemic, have tingling in their hands and feet or an unsteady gait, when vitamin B12 or folic acid are borderline;
- people following a vegan diet without supplements and older people, in whom vitamin deficiency is more likely;
- people taking metformin or acid-reducing medicines long term;
- people who had thrombosis or unexplained vascular disease at a younger age, as assessed by a specialist;
- people with suspected homocystinuria, a rare inherited disease usually detected in childhood.
What homocysteine shows
The body needs folate (vitamin B9), vitamin B12 and vitamin B6 to break down homocysteine. If one is deficient, blood homocysteine rises. It also rises with reduced kidney function. Elevated homocysteine is therefore a sensitive but non-specific sign: it suggests possible vitamin deficiency, while the cause is confirmed with other tests.
In studies, people with higher homocysteine more often have heart attacks, strokes and venous thrombosis. Large studies investigated whether lowering homocysteine with B vitamins helps. According to a Cochrane systematic review B vitamins did not reduce heart attacks or mortality, while strokes were only slightly less frequent. Associations with Alzheimer’s disease and osteoporosis have also been described, but causation has not been proven and homocysteine is not used to diagnose these diseases.
Homocysteine is therefore not a routine test for assessing heart disease risk in healthy people. The doctor assesses this risk according to age, blood pressure, smoking, sugar and blood fats; a basic test is the Lipid profile panel.
Panels including this test
Test Homocysteine is also included in this panel.
Preparation and sample
Homocysteine is measured in blood from a vein. Attend in the morning after an overnight fast, because a protein-rich meal may temporarily raise the value. You may drink water.
Mention at collection if you take B vitamins (B12, folic acid or B complex) or medicines such as methotrexate, metformin or epilepsy medicines, because these may alter results.
How results are interpreted
Homocysteine is expressed in µmol/L. In adults, values up to around 15 µmol/L are most often considered normal, but the threshold depends on method, age and sex, so use that printed on your report. Values are generally slightly higher in men and older people.
Slightly elevated homocysteine
A slight elevation is common and usually has an identifiable cause:
- vitamin B12 or folate deficiency, less commonly vitamin B6;
- reduced kidney function and an underactive thyroid;
- medicines such as methotrexate and certain epilepsy medicines;
- smoking and larger amounts of alcohol and coffee;
- common MTHFR gene variants, which raise homocysteine only slightly, mainly with folate deficiency.
The doctor then checks vitamin B12, folate and kidney function and treats the cause, replacing confirmed deficiencies with vitamins.
Very high homocysteine
Values several times above the upper limit are rare. They may indicate marked vitamin B12 or folate deficiency, severe kidney damage or an inherited homocysteine breakdown disorder and require specialist investigation.
A doctor always interprets results with vitamins, kidney function, medicines and your symptoms. Read more about homocysteine and blood pressure in the article Homocysteine and high blood pressure.
How to arrange testing
You can come for blood collection without an appointment or referral at one of our branches throughout Croatia (listed on the Contactpage). Prices for all tests and panels are listed in the service price list. Homocysteine is also part of the Cardiovascular health panel, alongside lipids, apolipoproteins, lipoprotein(a) and proBNP.
Frequently asked questions
What is a normal homocysteine value?
In adults, values up to around 15 µmol/L are most often considered normal. The exact threshold depends on the laboratory and is printed on the report.
Does elevated homocysteine mean I will have a heart attack?
No. Elevated homocysteine is associated with a somewhat greater risk, but does not predict a heart attack by itself and has not been proven to cause one. It is more important to treat the cause, such as vitamin deficiency, and check blood pressure, blood fats, sugar and smoking.
How can elevated homocysteine be lowered?
If the cause is vitamin B12 or folate deficiency, the doctor prescribes replacement. A diet rich in vegetables, pulses and whole grains, stopping smoking and reducing alcohol also help. Do not take high-dose folic acid yourself, because it may mask vitamin B12 deficiency, which then continues damaging nerves.
Do I need to fast for homocysteine?
Yes, morning fasting is recommended because a protein-rich meal may temporarily raise the result. Do not stop prescribed medicines for blood collection. If you take B vitamins, mention this at collection because they lower the result. Agree with your doctor whether to omit them temporarily before testing.