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Unit Code 8271:
IgG/Albumin Ratio, Spinal Fluid

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Useful For

The CSF index is useful in the diagnosis of individuals with multiple

sclerosis.  In the absence of a paired CSF and serum specimes, the

CSF IgG/albumin ratio can be assessed.

 

The index is independent of the activity of the demyelinating process.

Clinical Information

Elevation of IgG levels in the cerebral spinal fluid of  patients with

inflammatory diseases of the central nervous system (multiple

sclerosis, neurosyphilis, acute inflammatory polyradiculoneuropathy,

subacute sclerosing panencephalitis) is due to local (CNS) synthesis

of IgG.

 

The two most commonly used diagnostic laboratory tests for multiple

sclerosis are CSF index and oligoclonal banding.  The CSF index is

the CSF IgG to CSF albumin ratio compared to the serum IgG to serum

albumin ratio.  The CSF index is therefore an indicator of the relative

amount of CSF IgG compared to serum and any increase in the index

is a reflection of IgG production in the central nervous system.  The

IgG synthesis rate is a mathematical manipulation of the CSF index

data and can also be used as a marker for CNS inflammatory

diseases.

Reference Values

CSF IgG:  < or = 8.1 mg/dL

CSF albumin:  < or = 27.0 mg/dL

CSF IgG/albumin:  < or = 0.21

Interpretation

CSF IgG index is positive (elevated) in approximately 80% of

patients with MS.

 

Cautions

The CSF index can be elevated in other inflammatory demyelinating

diseases such as neurosyphillis, acute inflammatory polyradiculoneuropathy,

and subacute sclerosing panencephalitis.  Oligoclonal banding in

CSF is slightly more sensitive (85%) than the CSF index.  The use of

CSF index plus oligoclonal banding has been reported to increase

the sensitivity to over 90%.

Clinical Reference

Tourtellotte WW, Walsh MJ, Baumhefner RW, Staugaitis SM,

Shapshak P:  The current status of multiple sclerosis intra-blood-

brain-barrier IgG synthesis.  Ann NY Acad Sci 436:52-67,1984.

 

Bloomer LC, Bray PF:  Relative value of three laboratory methods

in the diagnosis of multiple sclerosis.  Clin Chem 27(12):2011-2013,1981.

 

Hische EAH, vander Helm HJ:  Rate of synthesis of IgG within the

blood-brain barrier and the IgG index compared in the diagnosis

of multiple sclerosis.  Clin Chem 33(1):113-114,1987.

 

Swanson JW:  Multiple Sclerosis:  Update in diagnosis and review of

prognastic factors.  Mayo Clin Proc 64:577-585,1989.

 

Markowitz H, Kokmen E:  Neurologic diseases and the cerebrospinal

fluid immunoglobulin profile.  Mayo Clin Proc 58:273-274,1983.

 

Key