Nutrients
Vitamin B12 Cobalamin
Important for red blood cells and nervous-system function - deficiency is common and easy to miss early on.
In short
- What is measured
- Vitamin B12 (cobalamin) is a water-soluble vitamin essential for red blood cell formation, neurological function, and DNA synthesis.
- What the value shows
- A serum B12 level reflects current dietary intake and absorption.
- Reference range
- > 300pg/mL
What it is
The basics
Vitamin B12 (cobalamin) is a water-soluble vitamin essential for red blood cell formation, neurological function, and DNA synthesis. The body cannot produce it - it must be obtained from food, primarily animal sources, or from supplementation.
What it tells you
Why this marker matters
A serum B12 level reflects current dietary intake and absorption. Persistent low levels can cause megaloblastic anaemia and - more insidiously - slowly progressive neurological symptoms (tingling, balance problems, memory issues). Because liver stores are large, deficiency can take years to become symptomatic, which is exactly what makes screening useful.
Reference range
Where the typical ranges sit
Adequate typically > 300 pg/mL; values 200–300 pg/mL are borderline and may warrant follow-up testing.
Standard ranges classify > 300 pg/mL (> 220 pmol/L) as adequate, 200–300 pg/mL (148–220 pmol/L) as borderline, and < 200 pg/mL (< 148 pmol/L) as deficient. Because serum B12 has limitations, borderline values are sometimes confirmed with a methylmalonic acid (MMA) or holotranscobalamin test, which more directly reflects functional B12 status.
Reference ranges differ between laboratories and guidelines. Your CHIRAYOU report uses the range reported by the analysing laboratory, and your interpretation should be discussed with a physician.
What affects it
Common influencers
- Diet (strict vegan or vegetarian diets without supplementation)
- Age-related decline in stomach acid (reduces absorption)
- Long-term proton-pump inhibitor (PPI) or H2-blocker use
- Long-term metformin use
- Pernicious anaemia and other autoimmune gastric conditions
- Bariatric surgery and other conditions affecting the small intestine
When to follow up
If your value is outside the range
A clearly low B12 value should be discussed with a physician - the cause matters as much as the value itself. Dietary deficiency is treated differently from absorption-related deficiency, and the latter may need ongoing supplementation or injections rather than a short course of tablets.
