Reference Values

Reference Range:

IgG:      <0.90

IgM:      <0.80

INTERPRETIVE CRITERIA:

IgG:

            <0.90                Antibody not detected

            0.9 – 1.09          Equivocal

            ≥ 1.10        Antibody detected

            IgM:

            <0.80                Antibody not detected

            0.80 – 0.99        Equivocal

            ≥ 1.00        Antibody detected

Diagnosis of central nervous system infections can be accomplished by demonstrating the presence of intrathecally-produced specific antibody. Interpreting results may be complicated by low antibody levels found in CSF, passive transfer of antibody form blood, and contamination via bloody taps.  The interpretation of CSF results must consider CSF-serum antibody ratios to the infectious agent.