Evaluation of Cobas 8000® for the quantification of albumin and IgG in serum and cerebrospinal fluid.

According to the 2017 revised McDonald criteria, the presence of oligoclonal bands (OCB) at isoelectric focusing (IEF) is useful for the diagnosis of Multiple Sclerosis (MS), including relapsing-remitting MS and primary progressive MS. In this context, the quantification of IgG in serum and CSF is required for IEF execution (to deposit the same amount of IgG in serum and CSF), while the quantification of albumin in serum and CSF allows the calculation of the albumin quotient. We have evaluated the analytical performances of Cobas 8000® analyzer for the quantification of albumin and IgG in serum and CSF. Coefficients of variation were below 3.3% for within-run precision and below 3.1% for between-run precision. Results were similar or better than those obtained on nephelometer Immage 800® and turbidimeter SPAPLUS®. The uncertainty of quantification of IgG in CSF was 9% and that of albumin in CSF was 12%. IgG and albumin measured on Cobas 8000® in serum and CSF showed good agreement with results obtained on the nephelometer Immage 800®, including for the classification of albumin quotient and CSF IgG index as normal or pathological. Therefore, Cobas 8000® is a valuable tool for the quantification of IgG and albumin in CSF, in the context of diagnosis of MS and other inflammatory disease affecting the central nervous system.