Phosphorylated Tau 181 (pTau-181)-15163
Test info
This blood-based biomarker is useful as an initial screen for Alzheimer’s disease in patients presenting with mild cognitive impairment before proceeding to more invasive and expensive diagnostic PET scanning or lumbar puncture.
Hepatic and renal function impact concentrations of pTau-181.
Results of plasma pTau-181 testing in patients with a history of myocardial infarction (MI) or clinical stroke should be interpreted with caution.
Specimen
Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
(Note: This volume does not allow for repeat testing.)
Immediately following collection, mix sample thoroughly by gentle inverting 8 - 10 times, to prevent clotting
- Spin within 2 hours of collection
- Transfer plasma to a Transfer vial/tube with cap - 12mL (LabCorp), labelled as EDTA plasma
Ambient (preferred) - 14 days
Refrigerated - 14 days
Frozen - 14 days
Freeze/thaw cycles - stable x3
- Serum specimen
- Improper labeling
Performance
Clinical and Interpretive info
• 0 - 55 years: 0.00–0.95 pg/mL
Reference interval is based on a population of ostensibly healthy individuals aged 20 to 55 years. Test performed by Roche Diagnostics Electrochemiluminescence Immunoassay (ECLIA). Values obtained with different methods cannot be used interchangeable.
• >55 years: 0.00–0.97 pg/mL
Results greater than the clinical cut-off of 0.97 pg/mL in patients greater than 55 years of age are correlated with Abeta amyloid pathology as determined by amyloid PET imaging. Test performed by Roche Diagnostics Electrochemiluminescence Immunoassay (ECLIA). Values obtained with different methods cannot be used interchangeable.