Vitamin B12 (Serum) with Antibody Screening

What This Test Measures

This test detects the presence of antibodies against vitamin B12 (also called cobalamin). Normally, your immune system doesn’t produce these antibodies, but certain conditions can trigger their formation. These antibodies may interfere with vitamin B12 absorption in your gut, potentially leading to deficiency symptoms.

Why It Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms of vitamin B12 deficiency (like fatigue, numbness, or weakness) or if you have conditions such as autoimmune disorders, chronic gastritis, or a history of stomach surgery that could affect vitamin B12 absorption.

Sample Collection and Preparation

A blood sample is drawn from a vein in your arm. The sample is sent to a lab where it is processed to separate serum (the liquid part of blood without clotting factors). The test measures antibodies against vitamin B12 using immunoassay methods.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if instructed by your provider. Avoid taking vitamin B12 supplements or certain medications that affect vitamin B12 levels for a few days before testing.