Crosswalk study on blood collection‐tube types for Alzheimer's disease biomarkers

INTRODUCTION: Blood‐based Alzheimer's disease (AD) biomarkers show promise, but pre‐analytical protocol differences may pose problems. We examined seven AD blood biomarkers (amyloid beta [[Formula: see text] , [Formula: see text] , [Formula: see text] , total tau [t‐tau], neurofilament light chain [NfL], [Formula: see text] and [Formula: see text]) in three collection tube types (ethylenediaminetetraacetic acid [EDTA] plasma, heparin plasma, serum). METHODS: Plasma and serum were obtained from cerebrospinal fluid or amyloid positron emission tomography‐positive and ‐negative participants (N = 38) in the Wisconsin Registry for Alzheimer's Prevention. We modeled AD biomarker values observed in EDTA plasma versus heparin plasma and serum, and assessed correspondence with brain amyloidosis. RESULTS: Results suggested bias due to tube type, but crosswalks are possible for some analytes, with excellent model fit for NfL ([Formula: see text] = 0.94), adequate for amyloid ([Formula: see text] = 0.40‐0.69), and weaker for t‐tau ([Formula: see text] = 0.04‐0.42) and [Formula: see text] ( [Formula: see text] = 0.22‐0.29). Brain amyloidosis differentiated several measures, especially EDTA plasma [Formula: see text] ([Formula: see text] = 1.29). DISCUSSION: AD biomarker concentrations vary by tube type. However, correlations for some biomarkers support harmonization across types, suggesting cautious optimism for use in banked blood.