Lab marker · High

High Homocysteine: what it means

A Homocysteine result above the normal range is considered high. Here is what a raised Homocysteine can point to, and when it is worth discussing with a doctor.

Reference range: 5–15 µmol/L; >15 mild, >30 moderate, >100 severe

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What a high Homocysteine can mean

  • B12 or folate deficiency — by far the commonest cause; corrects with supplementation.
  • Vitamin B6 deficiency — less common.
  • Chronic kidney disease — impaired clearance.
  • Hypothyroidism — slows the metabolism of homocysteine.
  • MTHFR genetic variants — modest elevation; clinical relevance debated.
  • Severe hyperhomocysteinaemia (>100 µmol/L) — classical homocystinuria; rare inherited condition with early thrombosis and skeletal abnormalities.

When to discuss with a doctor

Mild-moderate elevation usually responds to B12 + folate replacement. Severe elevation (>50–100 µmol/L) warrants specialist review for thrombosis risk and inherited homocystinuria. Mediora.AI flags the threshold; do not start B-vitamin therapy without confirming B12 and folate first — folate alone can mask undiagnosed B12 deficiency.

Conditions this can relate to

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Mediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.