p-Tau181

What it measures

Phosphorylated tau 181 (p-Tau181) is a form of tau protein associated with amyloid changes in the brain. This test measures it in EDTA plasma using the Roche Elecsys assay. Results are reported in pg/mL.

Who the test is for

The assay is intended for adults aged 55 to 80 with memory or other cognitive concerns who are being assessed for possible causes. Discuss suitability with your clinician. It is not a general screening test for people without cognitive concerns.

What a result can tell you

The Roche Elecsys assay used by Inuvi has a decision threshold of 0.934 pg/mL: at or below it is negative; above it is positive. This threshold is specific to this assay.

A negative result makes amyloid pathology less likely to explain cognitive symptoms. It does not explain those symptoms or rule out every cause of cognitive decline.

A positive result does not confirm Alzheimer’s disease. Your clinician may consider further assessment alongside your symptoms and medical history.

Use the interpretation on your laboratory report. This is not a percentage risk score or a measure to optimise. Results from different assays should not be treated as interchangeable, and p-Tau217 is a different marker.

How the sample is collected

A qualified healthcare professional takes a venous blood sample. Choose a home nurse visit, a clinic appointment with a posted kit, or a posted kit for a blood draw you arrange yourself. Do not self-collect the sample.

Source and interpretation

This guide describes the Roche Elecsys Phospho-Tau (181P) Plasma assay. It is educational information and does not replace clinical assessment.