Lumipulse pTau-217/Beta Amyloid 42 Ratio

https://www.labcorp.com/education-events/articles/atn-profile-and-beyond-alzheimers-disease Here is a link that explains the blood test for Alzheimer’s.

I hope the information helps. Take care.

I read that it got FDA approval in May. I plan to request it when next I see my mom's PCP. Mom's MRI shows Vascular Dementia but I think she has a mix as her Kappa/Llamba showed amyloid plaques, and I want to know..

Did insurance pay for it?

I don't claim to be an expert, but I'd suggest folks who are interested in the blood tests for AD read the Alzheimer's Association guidelines on this topic, published July 29, 2025 (link below).

The guidelines indicate you need to be aware of two parameters: the sensitivity of the blood test and the specificity. These two words have specific definitions for blood tests: sensitivity refers to how well the test identifies people who really have AD. A highly sensitive test rarely misses people who really have AD. Specificity refers to how well a test correctly identifies people who do not have AD.

The guidelines recommend that a blood test can be used as a triage test to determine the presence or absence of AD pathology (i.e. is there amyloid plaque in the brain or not), then the test should have at least 90% sensitivity and at least 75% specificity. To confirm the diagnosis, either a spinal tap or an amyloid PET scan would be required.

If the blood test is to be used for confirmation of AD as a substitute for the normal spinal tap or amyloid PET scan, then they Alzheimer's Associations recommends the test have 90% sensitivity and 90% specificity.

So to understand the usefulness of any AD blood test, you need to understand the sensitivity and specificity values.

I also suggest being wary of claims that any blood test can provide an estimate of the rate of progression of AD. I recently attended the Alzheimer's Association International Conference in Toronto. There was a lot of discussion about the various blood tests, the Association's new guidelines, and the sensitivity / specificity of the various tests. I didn't hear anybody make claims about estimating the rate of progression of AD.

The focus of the current blood tests seem to be serving as predictions of amyloid plaque in the brain, one of the hallmarks of AD. But the amyloid plaque is not the key driver in the cognitive decline. Rather, according to amyloid cascade theory, it is high levels of amyloid plaque which trigger the formulation of tau. Once the tau begins to collect inside neurons, the neurons become damaged and eventually die. This seems to be the driver in cognitive decline. Today, people can get tau PET scans which detect the amount and location of tau tangles inside neurons. I am not aware of any blood tests that can reliably determine tau levels inside neurons, despite what some companies selling their blood tests might claim.

https://alz-journals.onlinelibrary.wiley.com/doi/10.1002/alz.70535