Vitamin B12 (Cobalamin) Blood Test
Vitamin B12, also known as cobalamin, is involved in the metabolism of every cell in the human body. Because B12 must be obtained from the diet, people who eat little or no animal products, those with intestinal conditions, and older adults are at elevated risk of deficiency. Up to 20 % of the elderly population may have insufficient B12 levels. Early detection through blood testing allows timely supplementation before irreversible neurological damage occurs.
Why Test Vitamin B12?
A B12 test is recommended if you experience unexplained fatigue, brain fog, mood changes, numbness or tingling in your hands and feet. It is especially important for vegans, vegetarians, people with celiac disease or inflammatory bowel conditions, those on long-term proton-pump inhibitors or metformin, and women who are pregnant or breastfeeding. Regular monitoring helps ensure adequate intake and absorption.
What Do High Vitamin B12 Levels Mean?
Elevated serum B12 is most often caused by excessive supplementation. In rare cases, high levels may indicate liver disease, certain blood cancers (such as polycythaemia vera) or kidney dysfunction. Symptoms can include skin rashes, nausea, dizziness and anxiety. Discuss persistently high values with your healthcare provider to rule out underlying conditions.
What Do Low Vitamin B12 Levels Mean?
Low B12 suggests inadequate intake or impaired absorption and can lead to megaloblastic anaemia and progressive nerve damage. The serum test alone may miss mild deficiency, so a follow-up methylmalonic acid (MMA) or homocysteine test is recommended when results fall in the lower half of the reference range. Common causes include vegan diets, pernicious anaemia, celiac disease, SIBO and gastric bypass surgery.
Symptoms to Watch For
- Persistent fatigue and weakness
- Numbness or tingling in hands and feet
- Difficulty walking or balance problems
- Brain fog, memory loss and poor concentration
- Mood changes including depression, irritability and anxiety
- Swollen tongue and mouth ulcers
- Pale or yellowish skin
- Headaches and dizziness
Who Should Get Tested?
- Vegans and vegetarians not supplementing B12
- Adults aged 50 and over
- Pregnant or breastfeeding women
- People with celiac disease, Crohn's or other malabsorption conditions
- Those on long-term proton-pump inhibitors, metformin or antacids
- Anyone experiencing unexplained fatigue, brain fog or neurological symptoms
How to Prepare for Your Test
No fasting is required. If you take high-dose folic acid supplements, inform us before testing as they can mask B12 deficiency. Bring valid ID to the lab. If you take a supplement containing biotin (often sold for hair and nails), pause it for two days before the test, as high doses can distort the result.
Order Your Blood Test
Test your Vitamin B12 levels with an accredited Swedish laboratory. Results within days, reviewed by Wellth.
Frequently Asked Questions
What is a normal vitamin B12 level?
Can I have B12 deficiency even if my blood test is normal?
How is B12 deficiency treated?
How often should I test my B12?
Reviewed by
Wellth Team
Wellth
Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.
Learn more about our team →Medical Disclaimer
The information on this page is provided for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Wellth provides health information and testing services but is not a substitute for clinical care. Always consult a qualified healthcare provider if you have questions about a medical condition. If you are experiencing severe or urgent symptoms, contact your doctor or call 1177 Vårdguiden. Blood test results should be interpreted by a qualified healthcare professional in the context of your complete medical history.