Importance of the preanalytical phase: Elevation of protein levels in cerebrospinal fluid samples due to inappropriate containers

<b>Background:</b> Biomarkers in cerebrospinal fluid (CSF) are crucial for diagnosing, monitoring, and prognosing neurological disorders.<b>Purpose:</b> This study evaluates the impact of preanalytical variables, particularly container choice, on CSF protein measurements.<b>Analysis:</b> Using 30 CSF samples, we compared sterile, additive-free tubes and lithium heparin tubes without separator gel.<b>Results:</b> Protein levels were significantly elevated higher in heparin tubes (mean difference: 230.71 mg/dL, <i>P</i> < .001).<b>Conclusions:</b> This overestimation underscores the necessity of adhering to preanalytical protocols to avoid erroneous clinical interpretations and ensure accurate diagnostic outcomes.