BiomarkersHomocysteine

Heart & inflammation

Homocysteine

An amino acid that rises when B vitamins run low

On your report it may say: Hcy, Total homocysteine

Homocysteine is cleared with the help of B12, folate and B6. High levels are common in Indian vegetarians with low B12 and are linked to heart and blood vessel risk.

Updated 2026-10-26

Typical ranges · µmol/L

In range below 10
Upper normal 10–15
Raised 15–30
High 30+

Kidney function and some medicines also raise homocysteine.

Ranges vary by lab, age and sex. The range printed on your report applies.

If it's low

Your B-vitamin clearance is working well.

Common causes

  • Good B12, folate and B6 status

If it's high

Often a sign of low B12 or folate, and a heart risk factor in its own right.

Common causes

  • Low B12 (common in vegetarians)
  • Low folate or B6
  • Kidney disease
  • Genetic variants (such as MTHFR)
  • Smoking, coffee and alcohol

What you might notice

  • Usually none
  • Signs of low B12 if that's the cause

Testing

Who should test
Vegetarians, people with borderline B12, or a family history of early heart disease or clots.
How to prepare
Fasting sample is usually preferred.
When to retest
8–12 weeks after starting B vitamins.

What can help

Food sources

Dairy and eggs (B12)Leafy greens and pulses (folate)Bananas and chickpeas (B6)

See a doctor if it's above 30, or if you've had clots or early heart disease in the family.

Common questions

Does MTHFR mean I need methylfolate?

Not necessarily; homocysteine level is a better guide.

Why is it high in vegetarians?

Mainly because of low B12.

Explore further

Sources

  1. MedlinePlus (US National Library of Medicine): Homocysteine test
  2. NIH Office of Dietary Supplements: Folate fact sheet for health professionals
  3. NIH Office of Dietary Supplements: Vitamin B12 fact sheet for health professionals

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For general education only, not medical advice. Ranges shown are typical for adults; the range printed on your lab report applies. Talk to a qualified doctor about your results.