Immunoglobulin M (IgM) to IgG ratio in cerebrospinal fluid (CSF)

Why This Test Is Done

Your doctor may order this test if you have symptoms like headaches, neck stiffness, confusion, or neurological issues that suggest conditions such as meningitis, encephalitis, or other infections affecting the brain or spinal cord. It can also help diagnose or monitor conditions like multiple sclerosis or certain autoimmune diseases.

What to Expect Before the Test

No special preparation is needed. A healthcare provider will collect a small amount of cerebrospinal fluid through a procedure called a lumbar puncture (spinal tap). You may feel mild pressure or discomfort, but it’s generally quick and well-tolerated.

How the Test Results Are Interpreted

The ratio of IgM to IgG in CSF can differ based on the presence of infections (e.g., viral or bacterial), immune responses, or other neurological conditions. Elevated IgM levels relative to IgG may indicate recent infection or inflammation, while normal or low ratios could suggest other underlying issues.

Common Conditions Monitored

This test is often used to diagnose or evaluate conditions like meningitis, encephalitis, Guillain-Barré syndrome, or certain demyelinating diseases. It helps differentiate between infections, immune disorders, and other neurological conditions affecting the central nervous system.