p-tau217/Beta-Amyloid 42 Ratio, Plasma

The plasma p-tau217/beta-amyloid 42 ratio (Fujirebio Lumipulse G) is FDA cleared to help assess the presence or absence of amyloid plaques in adults aged 50 and older who show signs or symptoms of cognitive decline. A lower ratio makes amyloid pathology less likely; a higher ratio makes it more likely and typically warrants confirmatory evaluation (amyloid PET or CSF testing). It is an aid to diagnosis, not a standalone diagnosis, and has not been validated for screening people without symptoms.