p-Tau 181

How it works?

An accurate blood base biomarker for Alzheimer’s – p-Tau 181

When amyloid plack forms at the end terminal of the neurons in the brain, it is considered the hallmark of Alzheimer’s disease. The formation of amyloid plack aggregates signals to phosphorylate the tau tangles are sent upstream to the nucleus. This results in phosphorylation of tau in this area. Particular phosphorylation sites correlate very closely with Alzheimer’s pathology and can be measured either in spinal fluid or in blood. One of these biomarkers is called p-Tau 181. The 181 number refers to the particular location on the tau protein that is phosphorylated.

Levels of Phosphorylated Tau 181 (p-Tau 181) as well as a beta 42/40 in cerebrospinal fluid (CSF) have been measured to detect Alzheimer’s disease pathology for clinical use in several accredited laboratories around the World. In the last 5 years, more than 100 publications have shown that also the levels of pTau-181 in blood plasma have shown to correlate to Alzheimer’s pathology. The Alzheimer’s pathology was measured by the gold standard PET imaging and CSF studies of a beta 42/40. This ability to test for p-Tau 181 in plasma mitigates the need for invasive and expensive CSF tests. As well, the use of plasma pTau-181 as a blood biomarker makes for a simpler, more accessible method of detecting Alzheimer’s disease.

The assay performed by our lab is a highly sensitive, robust and accurate method of p-Tau 181 detection. Plasma isolated from blood is placed in a state-of-the-art instrument with automated sample preparation, data collection and data analysis. Results are reported in pg/ml and an interpretation based on your p-Tau 181 concentration will be included.


  • 1. Meng, J., & Lei, P. (2020). Plasma pTau181 as a biomarker for Alzheimer’s disease. MedComm, 1(1), 74–76. https://doi.org/10.1002/mco2.1

  • 2. Karikari, T. K., Pascoal, T. A., Ashton, N. J., Janelidze, S., Benedet, A. L., Rodriguez, J. L., Chamoun, M., Savard, M., Kang, M. S., Therriault, J., Schöll, M., Massarweh, G., Soucy, J. P., Höglund, K., Brinkmalm, G., Mattsson, N., Palmqvist, S., Gauthier, S., Stomrud, E., Zetterberg, H., … Blennow, K. (2020). Blood phosphorylated tau 181 as a biomarker for Alzheimer’s disease: a diagnostic performance and prediction modelling study using data from four prospective cohorts. The Lancet. Neurology, 19(5), 422–433. https://doi.org/10.1016/S1474-4422(20)30071-5

  • 3. Tissot, C., L Benedet, A., Therriault, J., Pascoal, T. A., Lussier, F. Z., Saha-Chaudhuri, P., Chamoun, M., Savard, M., Mathotaarachchi, S. S., Bezgin, G., Wang, Y. T., Fernandez Arias, J., Rodriguez, J. L., Snellman, A., Ashton, N. J., Karikari, T. K., Blennow, K., Zetterberg, H., De Villers-Sidani, E., Huot, P., … Alzheimer’s Disease Neuroimaging Initiative (2021). Plasma pTau181 predicts cortical brain atrophy in aging and Alzheimer’s disease. Alzheimer’s research & therapy, 13(1), 69. https://doi.org/10.1186/s13195-021-00802-x