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Vitamin B12

Cobalamin Serum B12 Cyanocobalamin
Serum (SST) ng/L (pmol/L)

About this test

Essential cofactor for DNA synthesis and myelin production. Deficiency causes macrocytic anaemia, subacute combined degeneration of the cord, and peripheral neuropathy. Serum B12 does not capture intracellular deficiency well; holotranscobalamin (active B12) and methylmalonic acid are more sensitive.

Reference Ranges

Sex Age Range Notes
All ≥ 18 yrs 197 – 771 Adult (varies by assay); <200 ng/L suggests deficiency; 200–300 borderline

Clinical Interpretation

Low / Decreased
Deficiency — strict vegan diet, pernicious anaemia (anti-IF antibody positive), atrophic gastritis, gastric surgery, metformin, IBD (terminal ileum resection), malabsorption.
High / Increased
Elevated — liver disease, myeloproliferative disorders, solid tumours (ectopic B12 production).
Specimen
Serum (SST)
Reporting Unit
ng/L (pmol/L)
Category
💊 Vitamins

⚠ Clinical Note
Reference ranges are indicative. Always interpret results in the context of the individual patient and local laboratory reference intervals, which may vary.