CSF IgG INDEX, CSF IgG

CLINICAL UTILITY:

The ratio of a patient’s IgG and albumin in cerebrospinal fluid (CSF) to the IgG and albumin in serum is of diagnostic value in a number of neurological disorders. In normal CSF, the albumin and IgG are derived from the serum, whereas in patients with active multiple sclerosis (MS), the increased CSF IgG is believed to be synthesized within the CSF. The CSF Index is a calculated value which expresses numerically the ratio of IgG to albumin in CSF, to the ratio of IgG to albumin in serum. An elevated ratio suggests local CNS synthesis of IgG. An increased CSF/IgG Index is found in diseases such as MS, neurosyphilis, subacute sclerosing panencephalitis (SSPE), chronic CNS infections and CNS lupus erythematosus.

METHOD DESCRIPTION:

The CSF IgG and the CSF/IgG Index are determined using a nephelometric technique. For the CSF IgG Index, the ratio of albumin and IgG in CSF is compared to the ratio of albumin and CSF in serum, and expressed as a single value.

REFERENCE RANGE:

CSF IgG: 0.5 - 6.1 mg/dl
CSF IgG Index: 0.34 - 0.66

SPECIMEN REQUIREMENTS:

1.0 ml CSF (0.5 ml min.) and 1.0 ml serum (0.5 ml min.) Freeze.