Day: August 11, 2026

Recently a patient inquired about p-Tau217 testing, so I’ve been doing a bit of a dive on the topic, and thought I’d share my thoughts on it. 

First, a bit of background. p-Tau217 is a protein that is found in abundance in the brain of Alzheimer’s disease patients. One of the tests that a neurologist might do when evaluating if a patient has Alzheimer’s disease or not is a lumbar puncture (aka a “spinal tap”) in which they stick a needle into a patient’s spine, withdraw some fluid, and send it to the lab to test for p-Tau217 as well as other proteins that are elevated in Alzheimer’s disease. 

However, about a year ago, the FDA approved a blood test for p-Tau217, which is now commercially available at labs like Quest. Studies have shown that an elevated p-Tau217 blood test is highly predictive of elevated p-Tau217 in the cerebrospinal fluid, making the test a good substitute for undergoing the much more invasive and unpleasant lumbar puncture. It also means that primary care doctors such as myself can now play more of a role in working patients up for Alzheimer’s.