Immunoglobulin M (IgM) Antibody to Mycoplasma pneumoniae

What This Test Measures

IgM antibodies are part of your immune system’s immediate response to infection. This test detects these antibodies to help identify if you’ve recently been exposed to *Mycoplasma pneumoniae*. IgM levels rise quickly after infection but decline over weeks to months, making this test useful for recent exposures.

Why It’s Ordered

Your healthcare provider may order this test if you have symptoms like cough, fever, or chest pain that suggest a respiratory infection, especially if other tests (like a throat culture or chest X-ray) are inconclusive. It’s often used alongside other tests to confirm or support a diagnosis.

When Results Might Be Positive

Results may be positive shortly after infection (within days to weeks) and can remain elevated for months. It’s less likely to be positive if the infection is very recent or if you’ve already recovered.

What to Expect Before the Test

No special preparation is needed. A blood sample is typically drawn from a vein in your arm. If you’re on blood-thinning medication or have a history of bleeding, let your provider know before the test.