What Is Homocysteine in a Blood Test?

Q: What Is Homocysteine in a Blood Test?

Homocysteine explained: normal range 5-15 µmol/L, what high homocysteine means for cardiovascular risk, B12/folate status, and how to lower it with supplementation.

Homocysteine is an amino acid produced during methionine metabolism. Normally converted back to methionine with B vitamins (B6, B12, folate).

Normal Range

5–15 µmol/L
Above 15 = hyperhomocysteinemia
Optimal: below 10 µmol/L

High Homocysteine Causes

Vitamin B12 deficiency
Folate deficiency
Vitamin B6 deficiency
MTHFR genetic mutations
Kidney disease
Medications — methotrexate, metformin, PPIs

Health Risks

Cardiovascular disease
Dementia and cognitive decline
Osteoporosis
Pregnancy complications
Venous thrombosis

Lowering Homocysteine

Folic acid — most effective
Vitamin B12 (methylcobalamin)
Vitamin B6
Dietary: leafy greens, animal products, bananas

Source: NLM MedlinePlus, American Association for Clinical Chemistry.

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