: Measles Virus IgG Antibody, Serum

: What This Test Measures

: The test detects immunoglobulin G (IgG) antibodies directed against the measles virus in a sample of serum, the clear liquid part of your blood. IgG antibodies typically appear after infection or vaccination and can stay in your body for many years, which is why this test is used to assess immunity.

: Why It Is Ordered

: Your healthcare provider may order this test to confirm whether you are immune to measles, to check immunity before travel or certain jobs, or as part of an evaluation after exposure or during an outbreak. It may also be used to help investigate a suspected measles illness, though other tests are usually needed for diagnosis.

: How the Sample Is Collected

: A small blood sample is drawn from a vein in your arm. No special preparation is usually required, but follow any instructions your provider gives you.

: How Results Are Interpreted

: Results are generally reported as positive, negative, or sometimes equivocal (unclear), along with the measured level. A positive result suggests measurable antibodies, while a negative result means they were not detected. Equivocal results may need to be repeated. The result is interpreted together with your vaccination and infection history, symptoms, and other findings, so a single result does not tell the whole story.