KAPPA INDEX IN CEREBROSPINAL FLUID SAMPLES OF PATIENTS WITH SUSPECTED MULTIPLE SCLEROSIS (MS)

Introduction: The evaluation of the intrathecal production of IgG is useful in the evaluation of MS suspected cases. The most precise test is the qualitative detection of oligoclonal bands (OCBs) in cerebrospinal fluid (CSF) and serum. Recent studies have reported that measuring CSF IgG free light chains (FLC), especially the Kappa Index, is comparable with OCBs as markers of IgG synthesis. It is still unknown if diagnostic sensitivity be increased by performing these two methods in parallel. Objective: The aim of this study was to evaluate the results of the Kappa index and the oligoclonal bands (BOCs) in samples from patients with suspected multiple sclerosis (MS). Method: Patients with suspected MS underwent cerebrospinal fluid (CSF) analysis. CSF samples were submitted to the detection of BOCs and kappa index. Results: One hundred and seventy-one serum and CSF samples were included, 76 of them had positive CSF BOCs. Among the BOC+ cases, 74 (97.4%) were also positive with the kappa index. Among the patients without BOCs, eight (8.4%) had a positive kappa index. Conclusion: The Kappa index showed to be at least almost as sensitive as the detection of BOCs. Positive kappa results found among cases without BOCs may be false positives but may also indicate false negative results with BOC. Therefore, it is possible that kappa index can help to diagnose cases of MS without detection of BOCs by increasing the sensitivity of intrathecal production of IgG.