Vitamin B12 – laboratory test

Opis produktu

Why vitamin B12 is tested

Vitamin B12 (cobalamin) is essential for red blood cell production, DNA synthesis and the formation of nerve sheaths. Deficiency develops slowly because liver stores last for years, but once depleted, it causes megaloblastic anaemia and nerve damage: numbness, balance problems, memory difficulties and low mood. Neurological symptoms can occur without anaemia and may be partly irreversible, so it is advisable not to wait for an abnormal full blood count.

When to consider this test

• a vegetarian or vegan diet (B12 is found only in animal products and fortified foods),
• anaemia, especially with large red blood cells (raised MCV), or an abnormal full blood count,
• numbness and tingling in the hands and feet, impaired sensation and balance, worsening memory or depression,
• long-term treatment with metformin or heartburn medicines (proton pump inhibitors), stomach and intestinal disorders (coeliac disease, Crohn’s disease, SIBO, or following bariatric surgery),
• age over 50, alcohol misuse, pregnancy or breastfeeding,
• monitoring treatment for deficiency.

How to prepare

• Fast for 8–12 hours, drinking only water in the morning. Have the sample collected in the morning.
• Avoid testing within 2 weeks of a B12 injection. Oral supplements raise the result; discuss whether to stop them with your doctor.
• Tell your doctor about metformin, heartburn medicines, contraception and alcohol consumption. Stop high-dose biotin for one day before sample collection.

Understanding your result

Results are reported in pg/ml (equivalent to ng/l) or pmol/l (1 pg/ml = 0,738 pmol/l). Laboratory reference ranges are broad (Mayo: 180–914 ng/l), but clinical decision thresholds are important in practice:

Investigating anaemia requires B12 and folate to be measured together, as folate treatment alone masks B12 deficiency and allows nerve damage to progress.

Other tests to consider alongside vitamin B12

Usually: full blood count, folate, ferritin; for a borderline result, homocysteine or methylmalonic acid; if an autoimmune cause is suspected, parietal cell antibodies and intrinsic factor antibodies. Symptoms and diet: Badania-Medyczne.pl.

Sources: ALAB laboratoria, Vitamin B12 (preparation, thresholds of 200/400 pg/ml, indications); Mayo Clinic Laboratories, Vitamin B12 Assay, Serum (reference range 180–914 ng/l, borderline range 150–400 ng/l, MMA, B12 injections). For information only; does not replace medical advice.