The Elecsys pTau181 test measures phosphorylated Tau 181 protein to help rule out Alzheimer’s-related amyloid pathology in patients 55 and older.
Labcorp will offer the Elecsys pTau181 test, the only blood test cleared by the US Food and Drug Administration (FDA) to aid in the initial assessment for Alzheimer’s disease and other causes of cognitive decline in primary care settings. The company plans to make Roche Diagnostics’ test available nationwide by early 2026.
The test is intended for adults ages 55 and older with signs, symptoms, or complaints of cognitive decline. Clinicians can order the test to help rule out Alzheimer’s-related amyloid pathology and identify patients who may benefit from further evaluation.
“Many patients presenting with cognitive symptoms don’t have Alzheimer’s disease, so helping clinicians rule it out can be just as critical as confirming it,” says Dr Brian Caveney, chief medical and scientific officer at Labcorp, in a release. “As a leader in neurology with the broadest portfolio of Alzheimer’s tests, Labcorp is proud to make the FDA-cleared Elecsys pTau181 test widely available—helping physicians identify the causes of cognitive decline and guide timely, appropriate care.”
An estimated 7.2 million Americans are living with Alzheimer’s disease, a number expected to nearly double by 2050. Cognitive changes are often identified during routine care visits, but Alzheimer’s biomarker testing has traditionally required a specialist referral and advanced invasive testing.
Test Performance and Clinical Utility
The Elecsys pTau181 test measures phosphorylated Tau (pTau) 181 protein in human plasma, a key biomarker for Alzheimer’s pathology, including amyloid plaque and tau aggregate pathology. According to Roche, clinical results demonstrated the test could rule out Alzheimer’s pathology with a 97.9% negative predictive value.
A negative test result is consistent with a negative amyloid positron emission tomography (PET) scan result and reduced likelihood that a patient’s cognitive impairment is due to amyloid pathology. These patients should be investigated for other causes of cognitive decline. Patients with an initial positive result should be further investigated to determine whether the amyloid pathology can be a cause of cognitive impairment.
Performed via a blood draw, the test offers an accessible, more affordable and less invasive alternative to traditional tests such as cerebrospinal fluid testing obtained through lumbar puncture and PET scans. Once the test is ordered, the blood draw can be completed in a doctor’s office or at any of Labcorp’s more than 2,200 patient service centers nationwide.
Expanding Alzheimer’s Testing Portfolio
Since March 2023, Labcorp has offered a laboratory-developed test version of pTau181, and in October 2023, added it to the company’s ATN Profile—a panel combining three key biomarkers to identify and assess biological changes associated with Alzheimer’s disease. Most recently, Labcorp launched the FDA-cleared Lumipulse pTau-217/Beta Amyloid 42 Ratio to aid in the diagnosis of Alzheimer’s disease for use in specialty care settings.
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