Effect of Sample Collection Tubes on Cerebrospinal Fluid Concentrations of Tau Proteins and Amyloid β Peptides

Abstract

Tau protein and its phosphorylated forms, and amyloid β peptides ending at amino acid 42 (Aβ42) are used as cerebrospinal fluid (CSF) biomarkers of Alzheimer disease (AD) (1)(2)(3)(4)(5)(6)(7)(8). Because preanalytical factors may affect results (4)(9)(10), we measured these biomarkers in CSF samples in collection tubes made of different materials. After approval by the Ethics Committee of the University of Erlangen-Nuremberg, patients and/or their closest relatives gave written informed consent. CSF was obtained from patients (n = 20; mean age, 66 years; 9 women and 11 men) with various neuropsychiatric diseases, including dementias (n = 9), mild cognitive impairment (n = 8), recurrent depression (n = 1), bipolar disorder (n = 1), and emotionally unstable personality (n = 1). We included only CSF samples showing no or only minor contamination with erythrocytes (<150/μL), no intrathecal humoral or cellular immune response, and normal or only slightly disturbed blood–CSF barrier as measured by albumin quotient. After collecting 4–5 mL of CSF for routine …