Quantitative Assessment of the Effect of Chronic Kidney Disease on Plasma P-Tau217 Concentrations

BACKGROUND AND OBJECTIVES: Chronic kidney disease (CKD) is known to be associated with increased plasma phosphorylated tau217 (p-tau217) concentrations, potentially confounding the utility of plasma p-tau217 measurements as a marker of amyloid pathology in individuals with suspected Alzheimer disease (AD). In this study, we quantitatively investigate the relationship of plasma p-tau217 concentrations vs estimated glomerular filtration rate (eGFR) in individuals with CKD with and without amyloid pathology. METHODS: N Diagnostics). Amyloid positivity was defined by amyloid-PET and a centiloid of ≥25. Log-log linear regression fits were used to quantitatively predict increases in plasma p-tau217 associated with decreasing eGFR. RESULTS: N %p-tau217, respectively. For the A+ cohort, the corresponding calculated percentage changes were +17%, +15%, and -5%, respectively. DISCUSSION: N methodologies, but the effect was mitigated by the use of %p-tau217. These results indicate limitations for the utility of plasma p-tau217 measurements in individuals with significant renal impairment (eGFR <45 or CKD stage 3b or greater). Determination of eGFR should be considered to avoid inaccurate classification of the presence of AD-related pathology by plasma p-tau217 in individuals with CKD. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that in individuals with CKD stage 3 (especially stage 3b) or higher, p-tau217 concentrations are increased, with a greater increase in amyloid-PET-negative individuals.