Vitamin B12 (Serum) – Mass Concentration

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like fatigue, numbness, tingling in the hands/feet, weakness, or unexplained anemia. It may also be checked during routine blood work, especially if you have conditions like pernicious anemia, celiac disease, or chronic gastritis, or if you’re on certain medications that interfere with vitamin B12 absorption.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on long-term vitamin B12 supplements or medications, let your provider know—this may affect results.

What the Results Mean

Results are compared to a reference range for healthy adults. Low levels may suggest vitamin B12 deficiency, which can be caused by poor diet, malabsorption issues, or certain medical conditions. High levels are less common but may indicate over-supplementation or rare genetic disorders.

Common Causes of Low Vitamin B12

Deficiencies often stem from dietary lack (e.g., vegan diets), impaired absorption (e.g., stomach disorders, strict diets without B12), or conditions like pernicious anemia. Chronic conditions like Crohn’s disease or kidney disease may also contribute.