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Lab test

Quest AD-Detect® Phosphorylated tau217 (p-tau217), Plasma Test

This test quantitatively measures phosphorylated tau protein at position 217 (p-tau217) in a plasma sample, using an immunoassay method.

Quest patient service center

About this test

The test measures p-tau217 in a plasma sample collected in an EDTA (lavender-top) tube. Quest notes that plasma p-tau217 levels have been reported to be concordant with amyloid status as determined by CSF or PET testing, and that the marker may help differentiate Alzheimer's disease from other neurodegenerative diseases or relate to how the disease is progressing.

Quest describes blood-based biomarkers like plasma p-tau217 as being explored as tools for research inclusion criteria or for evaluating effects observed in research related to Alzheimer's disease and related disorders.

Who might consider this test?

  • Quest frames this marker as being explored as a research tool, not as a routine result read on its own.

Test details

CollectionQuest patient service center

Quest resources

Additional details

What this test looks at

The test reports a quantitative p-tau217 value from plasma, measured by immunoassay. Quest lists preparation for this test: avoiding biotin for at least 72 hours before the blood draw.

This test isn't part of the Celio Health store at the moment, so it can't be ordered or requested here. The test menu lists everything that can.

Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.

Frequently asked questions

What does this test measure?

It quantitatively measures phosphorylated tau217 (p-tau217) in a plasma sample, using an immunoassay method.

How is the sample collected?

The test uses a plasma sample collected in an EDTA (lavender-top) tube.

Do I need to prepare for this test?

Yes. Quest lists preparation for this test: avoiding biotin for at least 72 hours before the blood draw.

What is p-tau217 also called?

Quest lists this test under several related names, including pT217 and Phosphorylated Tau 217.

Last updated 2026-09-18 · How we write about lab testing

Educational content

This page is for general educational purposes only. It is not medical advice, and it is not a substitute for consultation with a qualified healthcare professional. Laboratory results should always be interpreted by a licensed clinician who knows your health history. If you have questions about your health or your results, talk with your doctor. If you think you may be experiencing a medical emergency, call 911.