Cerebrospinal Fluid Collection Tubes: A Critical Issue for Alzheimer Disease Diagnosis

Abstract

To the Editor: Total tau protein (hTau),1 its phosphorylated isoform (p-Tau181P), and Aβ1–42 peptides are the currently accepted cerebrospinal fluid (CSF) biomarkers used as aids in the diagnosis of Alzheimer disease (1). Although polypropylene (PP) was previously reported as the best material for CSF collection tubes (2), heterogeneity in CSF Aβ1–42 values was observed with different PP sampling tubes (3). Because the recommendation to use PP tubes did not lead to standardization of clinical cutoff values (4), we decided to fully address this issue by comparing various types of tubes within an actual clinical work flow and by analyzing the material of different commercially available PP tubes. In the framework of an ethically approved study, we collected CSF samples from 12 patients directly (from the lumbar puncture needle) into 2 PP tubes [BD catalog no. 352096 (BD-PP); Sarstedt catalog no. 62.610.201 (ST-PP)], 1 hemolysis polyethylene tube [Fisher Scientific catalog no. ref.W1773X (HE-PE)], and 1 polystyrene tube [BD catalog no. 352095 (BD-PS)]. CSF biomarker concentrations were measured in parallel in these 4 types of tubes with Innogenetics INNOTEST® kits. We extended this analysis by comparing the results obtained with 11 different commercially available collection tubes labeled as “PP” for a series of fresh (unfrozen) …