Head-to-Head Comparison of Different Blood Collecting Tubes for Quantification of Alzheimer's Disease Biomarkers in Plasma

To examine whether the type of blood collection tubes affects the quantification of plasma biomarkers for Alzheimer's disease analyzed with a single-molecule array (Simoa), we recruited a healthy cohort (n = 34, 11 males, mean age = 28.7 +/- 7.55) and collected plasma in the following tubes: dipotassium ethylenediaminetetraacetic acid (K2-EDTA), heparin lithium (Li-Hep), and heparin sodium (Na-Hep). Plasma tau, phosphorylated tau 181 (p-tau181), amyloid beta (1-40) (A beta 40), and amyloid beta (1-42) (A beta 42) were quantified using Simoa. We compared the value of plasma analytes, as well as the effects of sex on the measurements. We found that plasma collected in Li-Hep and Na-Hep tubes yielded significantly higher tau and p-tau181 levels compared to plasma collected in K2-EDTA tubes from the same person, but there was no difference in the measured values of the A beta 40, A beta 42, and A beta 42/40 ratio. Therefore, the type of blood collecting tubes should be considered when planning studies that measure plasma tau.