CSF IgG Index

CSF is a clear, colorless fluid that flows in and around your brain and spinal cord. Your brain and spinal cord make up your central nervous system. Cerebrospinal fluid cushions your central nervous system from impact or injury. It also removes waste products from the brain and helps your central nervous system work right.

Normally you have a tiny amount of IgG in your cerebrospinal fluid. High levels of IgG may mean you have an infection or an inflammatory or autoimmune disease that involves your central nervous system. An autoimmune disorder causes your immune system to attack your own healthy cells by mistake, which can lead to serious health problems.

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. You may need more tests before your provider can diagnose your condition.

A CSF IgG index that's normal or lower than normal usually means there is no extra IgG being produced inside your central nervous system, which is a reassuring result that argues against active inflammation in the brain or spinal cord. A low CSF IgG index does not mean your body is unable to make enough IgG overall; problems with overall (systemic) IgG production are checked using a blood test for IgG, not a CSF test.

If you have questions about your results, talk with your provider.