CSF Immunoglobulin G (IgG) Index
Reviewed
Also called: Cerebrospinal fluid IgG level, Cerebrospinal fluid IgG measurement, CSF IgG level, IgG (Immunoglobulin G) spinal fluid, IgG synthesis rate
A CSF IgG index measures the levels of IgG in your cerebrospinal fluid. Normally you have a tiny amount of IgG in your cerebrospinal fluid.
Specimen: Cerebrospinal fluid
Why this test may be ordered
- To check for diseases of the central nervous system
- To help diagnose multiple sclerosis (MS)
- If you have symptoms such as blurred or double vision, tingling, numbness, pain, muscle spasms, weakness, dizziness, balance problems, bladder control issues, fatigue, or problems with thinking or memory
Preparation and collection
You don't need any special preparations for a CSF IgG index, but you may be asked to empty your bladder (pee) and bowels (poop) before the test.
To get a sample of cerebrospinal fluid, a provider will do a procedure called a spinal tap, also known as a lumbar puncture. A spinal tap is usually done in a hospital. Your provider will withdraw a small amount of cerebrospinal fluid for testing. You'll need to stay very still while the fluid is being withdrawn. Your provider may ask you to lie on your back for an hour or two after the procedure.
There is very little risk to having a spinal tap. You may feel a little pinch or pressure when the needle is inserted. After the test, you may feel some pain or tenderness in your back at the site where the needle was inserted. You may also have some bleeding at the site or get a headache. The headache may last for several hours or up to a week or more. Your provider may suggest treatment to help relieve the pain.
Understanding results
High levels of IgG may mean you have an infection or an inflammatory or autoimmune disease that involves your central nervous system.
- Higher than normal: A CSF IgG index that's higher than normal may be a sign of an infection or an inflammatory or autoimmune condition that affects your central nervous system, such as: Multiple sclerosis, Transverse myelitis (TM), Syphilis that infects your nervous system (neurosyphilis), Connective tissue disorders, Guillain-Barre syndrome, Encephalitis caused by herpes simplex. Limitation: The CSF IgG index is often used to help diagnose multiple sclerosis (MS), but there is no specific test for MS. Next step: You may need more tests before your provider can diagnose your condition.
- Lower than normal: A CSF IgG index that's lower than normal may be a sign that your body is unable to make enough IgG antibodies, and you are likely to get sick with infections. Limitation: Experts don't know what causes this problem. Next step: Normally, a test of IgG levels in blood is used to check whether you may lack IgG antibodies.
- A CSF IgG test alone cannot diagnose multiple sclerosis or any other condition.
- There is no specific test for multiple sclerosis.
- Results must be interpreted by a healthcare professional in the context of your symptoms and other tests.
- The test does not provide a definitive diagnosis; additional testing is often needed.
What to do next
If you have questions about your results, talk with your provider.
- What do my CSF IgG index results mean in my specific situation?
- What other tests might I need to help diagnose my condition?
- What are the next steps if my results suggest multiple sclerosis?
- Can my symptoms be explained by something other than a central nervous system disorder?
- How should I prepare for any follow-up tests or appointments?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: CSF Immunoglobulin G (IgG) Index