Experiments included synthetic peptide pT181 control material, buffer, and healthy, adult human plasma specimens collected in EDTA. The LUMIPULSE G1200 System (Fujirebio Inc.) chemiluminescent enzyme immunoassay (CLEIA) platform was used to process plasma samples using single analyte, ready-to-use immunoreaction cartridges. Precision, limit of detection (LOD), limit of blank (LOB), interference, analytical measurement range (AMR), accuracy, cross-reactivity, carry-over, specimen stability and reference interval across apparently healthy, adult donors (n=132) using the non-parametric method were determined.

Intra-assay precision (CV%) was <3.52; inter-assay CV% was <4.93 (sigma >5.0). LOB and LOD were defined at 0.03 pg/mL and limit of quantitation at 0.05 pg/mL, encompassing an AMR of 0.05–10.00 pg/mL. Accuracy showed peer group values across multiple concentration levels met reproducibility. Interference from hemoglobin (up to 1,500 mg/dL), lipids (1,000 mg/dL), or bilirubin (40 mg/dL) was not observed. Carry-over and cross reactivity tested with pT181 up to 60 pg/mL yielded results at LOB (0.03 pg/mL). Specimens were stable at room temperature (15-30°C) for 5 days, refrigerated (2-8°C) for 14 days, frozen (-30 to -10°C) for 28 days, and for up to 5 freeze-thaw cycles. Reference range was set to ≤0.15 pg/mL.

This study determined the analytical performance and reference interval for the Quest AD-Detect^® Phosphorylated tau217 (p-tau217), Plasma assay, which helps assess whether mild cognitive impairment or dementia is caused by AD. This test’s performance characteristics are suitable for use in evaluation of AD and non-AD neurodegenerative diseases.