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Biomarkers

p-tau217

p-tau217 is tau protein phosphorylated at threonine 217 and the most Alzheimer-specific plasma biomarker currently available. Concentrations rise early along the amyloid cascade, before cognitive symptoms emerge, and correlate tightly with amyloid-PET and tau-PET burden. In head-to-head comparisons plasma p-tau217 outperforms p-tau181, p-tau231 and several MRI-based markers for discriminating Alzheimer disease from other neurodegenerative disorders. Two-step workflows using plasma p-tau217 reduce the need for amyloid-PET or cerebrospinal fluid testing when triaging patients with cognitive impairment for anti-amyloid therapy. Pre-analytical handling, assay platform and reference ranges still vary across vendors. The first FDA-cleared blood test for Alzheimer disease (Fujirebio Lumipulse G pTau217/β-Amyloid 1-42 plasma ratio, May 2025) uses a plasma p-tau217 ratio; Roche received an EU CE mark for the Elecsys pTau217 plasma assay on 12 May 2026.

Sources

  1. Palmqvist S, Janelidze S, Quiroz YT, Zetterberg H, Lopera F, Stomrud E, et al.. (2020). Discriminative Accuracy of Plasma Phospho-tau217 for Alzheimer Disease vs Other Neurodegenerative Disorders. *JAMA*doi:10.1001/jama.2020.12134
  2. Janelidze S, Mattsson N, Palmqvist S, Smith R, Beach TG, Serrano GE, et al.. (2020). Plasma P-tau181 in Alzheimer's disease: relationship to other biomarkers, differential diagnosis, neuropathology and longitudinal progression to Alzheimer's dementia. *Nature Medicine*doi:10.1038/s41591-020-0755-1
  3. Mattsson-Carlgren N, Janelidze S, Palmqvist S, Cullen N, Svenningsson AL, Strandberg O, et al.. (2020). Longitudinal plasma p-tau217 is increased in early stages of Alzheimer's disease. *Brain*doi:10.1093/brain/awaa286