Stability of plasma pTau217/Aβ42 ratio with delayed blood processing.

Authors

Hana Mayfield, Casey S John, Jenae Pennington, Riley E Kemna, Maggie Kroeger, Amitava Dasgupta, Jeffrey M Burns, Fanny M Elahi, Melody Nelson, Jill K Morris

Published in

Alzheimer's & dementia (Amsterdam, Netherlands). Volume 18. Issue 4. Pages e70517. Epub Oct 20, 2026.

Abstract

Blood-based biomarkers may improve access to Alzheimer's disease diagnosis, but use may be limited in clinics without on-site processing capability. We evaluated the stability of the plasma phosphorylated tau 217 (pTau217)/amyloid beta 42 (Aβ42) ratio after delayed whole-blood processing.
We compared blood processed within 2 h or held at 4°C for approximately 24 or 48 h before centrifugation and analysis using the Fujirebio Lumipulse G1200. Stability was assessed using ordinary least squares regression, error index, Bland-Altman analysis, and Deming regression.
Correlations with the 2-h condition were high at both 24 and 48 h (R = 0.998). Both delayed conditions met prespecified regression and error-index criteria. Mean absolute percent error was 5.6% at 24 h and 9.8% at 48 h. Deming regression showed no constant bias, although proportional bias was observed at 48 h. No bias was observed for individual analytes for up to 48 h.
The pTau217/Aβ42 ratio in refrigerated whole blood remained stable for 24 h, with possible utility up to 48 h, supporting more flexible specimen-transport workflows.

PMID:
42908786
Bibliographic data and abstract were imported from PubMed on 23 Oct 2026.

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