IgG (Immunoglobulin G) is a vital part of your immune defense system. Abnormal levels—either too high or too low—can be a sign of chronic infection, autoimmune activity, immune deficiency, or other systemic conditions. Whether you're experiencing frequent infections or unexplained inflammation, this test offers critical insight into how your immune system is functioning and what steps may be needed next.

IgG, Quant, CSF stands for Immunoglobulin G, Quantitative, Cerebrospinal Fluid. This test measures the concentration of IgG, a type of antibody, in your cerebrospinal fluid (CSF)—the clear fluid that surrounds your brain and spinal cord.

What is IgG?

Immunoglobulin G (IgG) is the most abundant antibody in the body. It plays a critical role in immune defense by identifying and neutralizing viruses, bacteria, and other foreign substances. IgG is normally found in the blood but can also be present in small amounts in the CSF.

IgG is a combination of four slightly different types of IgG called IgG subclasses: IgG1, IgG2, IgG3 and IgG4. When one or more of these subclasses is persistently low and total IgG is normal, a subclass deficiency is present.

IgG is a combination of four slightly different types of IgG called IgG subclasses: IgG1, IgG2, IgG3 and IgG4. When one or more of these subclasses is persistently low and total IgG is normal, a subclass deficiency is present.

IgG is a combination of four slightly different types of IgG called IgG subclasses: IgG1, IgG2, IgG3 and IgG4. When one or more of these subclasses is persistently low and total IgG is normal, a subclass deficiency is present.

IgG is a combination of four slightly different types of IgG called IgG subclasses: IgG1, IgG2, IgG3 and IgG4. When one or more of these subclasses is persistently low and total IgG is normal, a subclass deficiency is present.

The IgG Synthesis Rate (CSF) measures how much immunoglobulin G (IgG) is being actively produced within the central nervous system (CNS)—specifically the brain and spinal cord. It helps determine whether the immune system is generating antibodies inside the CNS, which can signal inflammation, infection, or autoimmune activity affecting the brain or spinal cord.

Why it matters:
While some IgG naturally crosses from the blood into the cerebrospinal fluid (CSF), an elevated IgG synthesis rate means the immune system is producing extra IgG locally within the CNS. This is a hallmark of conditions like multiple sclerosis (MS), chronic CNS infections, or autoimmune neuroinflammatory diseases.

The IgG/Alb Ratio, CSF helps distinguish whether elevated IgG in the cerebrospinal fluid is due to local immune activity or simply leakage through a damaged blood-brain barrier. A high ratio often points to neurological conditions like multiple sclerosis or chronic CNS infections. A normal or low ratio suggests stable immune activity and barrier integrity.

IL-1 beta refers to Interleukin-1 beta. Interleukin-1 beta is one of the cytokines assessed in the CytoDx Cytokine Response Profile offered by Diagnostic Solutions Laboratory. Cytokines are critical mediators of immune responses, and their imbalances have been linked to chronic inflammation and autoimmune diseases.