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Lab test

IgM (Immunoglobulin M) Test

This test measures the level of immunoglobulin M (IgM) in a blood sample. IgM is a class of antibody, and its level can run higher or lower depending on a range of conditions a clinician may be evaluating.

Blood drawQuest patient service center

About this test

Immunoglobulin M, or IgM, is one of the antibody classes the immune system produces, and this test uses an immunoturbidimetric method on a serum sample to quantify it. Quest associates higher IgM levels with conditions including Waldenstrom's macroglobulinemia, infectious mononucleosis, other viral infections, nephrotic syndrome, and estrogen therapy.

Quest associates lower IgM levels with a different set of conditions, including selective IgM deficiency, Bruton's Disease, and acquired immune deficiency. Because both higher and lower results are associated with distinct conditions, a clinician reads an IgM result together with symptoms and other findings rather than on its own.

Who might consider this test?

  • It is frequently ordered alongside other immunoglobulin measurements rather than by itself.

Test details

Quest code545
MethodologyImmunoturbidimetric
Sample type1 mL serum
CollectionQuest patient service center

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Quest resources

Additional details

What this test looks at

The test reports one value: the concentration of IgM in a serum sample. Quest lists a range of conditions associated with both higher and lower IgM levels, which is why the result is interpreted in the context of the reason it was ordered.

Order online and a physician order is included — no doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.

Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.

Frequently asked questions

What does this test measure?

It measures the concentration of immunoglobulin M (IgM) in a serum sample, using an immunoturbidimetric method.

How is the sample collected?

The test uses a serum sample from a routine blood draw.

Do I need to prepare for this test?

No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.

What is a higher IgM level associated with?

Quest associates higher IgM levels with conditions including Waldenstrom's macroglobulinemia, infectious mononucleosis, other viral infections, nephrotic syndrome, and estrogen therapy.

What is a lower IgM level associated with?

Quest associates lower IgM levels with conditions including selective IgM deficiency, Bruton's Disease, and acquired immune deficiency.

How much is a IgM test?

$55, paid once at checkout. The price includes the physician's order this test requires and sample collection at a Quest patient service center.

Last updated 2026-09-18 · How we write about lab testing

Educational content

This page is for general educational purposes only. It is not medical advice, and it is not a substitute for consultation with a qualified healthcare professional. Laboratory results should always be interpreted by a licensed clinician who knows your health history. If you have questions about your health or your results, talk with your doctor. If you think you may be experiencing a medical emergency, call 911.