AUTHOR=Seeliger Tabea , Gingele Stefan , Güzeloglu Yunus Emre , Heitmann Lena , Lüling Benjamin , Kohle Felix , Preßler Hannah , Stascheit Frauke , Motte Jeremias , Fisse Anna Lena , Grüter Thomas , Pitarokoili Kalliopi , Skripuletz Thomas 

TITLE=Comparative analysis of albumin quotient and total CSF protein in immune-mediated neuropathies: a multicenter study on diagnostic implications

JOURNAL=Frontiers in Neurology

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1330484

DOI=10.3389/fneur.2023.1330484

ISSN=1664-2295

ABSTRACT=<sec id="sec1"><title>Introduction</title><p>Blood-cerebrospinal fluid (CSF) barrier dysfunction is pivotal for diagnosing immune-mediated neuropathies, especially in spinal nerve root inflammation. Typically, either total CSF protein or the CSF to serum albumin ratio (Q<sub>Alb</sub>) is measured. Total CSF protein measurements have limitations, notably its fixed reference value regardless of age, in contrast to the age-dependent reference for Q<sub>Alb</sub>. Our goal was to evaluate both markers in patients with immune-mediated neuropathies.</p></sec><sec id="sec2"><title>Methods</title><p>In our multicenter research, we collected retrospective CSF data from patients suffering from immune-mediated neuropathies across four German research centers. These parameters were analyzed in relation to their clinical characteristics.</p></sec><sec id="sec3"><title>Results</title><p>Out of 419 samples, 36 (8.6%) displayed a notable variation between total CSF protein and Q<sub>Alb</sub> values. A detailed analysis revealed that patients displaying elevated Q<sub>Alb</sub> but normal total CSF protein levels were significantly younger at disease onset (<italic>p</italic> = 0.01), at the time of diagnosis (<italic>p</italic> = 0.005), and when undergoing lumbar puncture (<italic>p</italic> = 0.001) compared to patients with elevated CSF protein and normal Q<sub>Alb</sub> levels. These effects were especially evident for the subgroup of samples derived by female patients.</p></sec><sec id="sec4"><title>Discussion</title><p>Our work confirms the crucial role of Q<sub>Alb</sub> in diagnosing immune-mediated neuropathies and particularly its efficacy as a marker for evaluating the blood-CSF barrier in patients with an earlier disease onset. Considering the significance of the albumin quotient, its assessment is especially advisable in younger patients of female sex to avoid missing a potential barrier dysfunction that might be falsely negative when using total protein.</p></sec>