Serum or Plasma Immunoassay for Vitamin B12 (Cobalamin) Concentration

Why This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms like fatigue, weakness, numbness, or tingling in your hands and feet. It could also be done to check for vitamin deficiencies, especially if you have conditions like pernicious anemia, celiac disease, or poor diet. Additionally, it may be part of routine blood work for certain health monitoring needs.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if your doctor specifies it. Bring any medications you’re currently taking, as some may affect results. If you’re pregnant, have recent surgery, or have a bleeding disorder, let your doctor know.

What Happens During the Test

A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a quick pinch, but it usually doesn’t cause significant discomfort. The blood sample is then sent to a lab for analysis using an immunoassay method to detect vitamin B12 levels.

What the Results Mean

Low vitamin B12 levels may indicate deficiencies caused by poor absorption (e.g., due to stomach issues, diet, or certain medications). High levels might suggest overconsumption or rare genetic conditions. Your doctor will interpret results in the context of your symptoms and overall health.