What is this test?
This test measures the total amount of immunoglobulin M in the blood. IgM is often among the first antibodies that the immune system forms upon new contact with a pathogen.
Why might it be ordered?
- For recurrent or unusual infections when an immune deficiency is being considered.
- To evaluate increased antibody formation in inflammatory, liver or certain blood diseases.
What sample is needed?
A healthcare professional collects a venous blood sample. Depending on the method, the laboratory uses serum or plasma.
How should you prepare?
Tell the laboratory about all medicines, hormone treatments, vitamins and supplements you take. Do not stop or change treatment unless your clinician tells you to. Follow any instructions about fasting and the time of collection.
How should you understand the result?
The total amount does not show which specific pathogen any antibodies target. An abnormal result is considered with the other immunoglobulins, protein electrophoresis and clinical findings. Your result is interpreted using the reference interval on the laboratory report and in the context of your symptoms, medical history and other test findings.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.