IMMUNOGLOBULIN-M IN CEREBROSPINAL-FLUID - REFERENCE VALUES DERIVED FROM 111 HEALTHY-INDIVIDUALS 18-88 YEARS OF AGE

The importance of immunoglobulin M (IgM) determination in cerebrospina l fluid (CSF) has increased parallel to the need for early diagnosis o f infectious and inflammatory disorders of the central nervous system. Current reference values are based on analysis of CSF from 'reference groups' consisting of patients with psychiatric and/or neurological s ymptoms but without positive clinical findings. Therefore, accurate re ference values for CSF IgM are of utmost importance. The present study presents reference values for IgM in CSF in a large sample (n = 111) of healthy individuals with an age span of 18-88 years. The upper refe rence limit, calculated as the 0.95 fractile, was 0.36 mg/l for CSF Ig M, 0.40 for CSF/serum IgM ratio, and 0.045 for the IgM index. These pa rameters showed no significant difference between sexes nor any signif icant correlations with age. The correlations between CSF/serum albumi n ratio and CSF/S IgM ratio were linear and statistically highly signi ficant, suggesting that the IgM index values do not depend on the bloo d-CSF barrier function within the normal range of the CSF/serum albumi n ratio.