Elecsys CSF AD immunoassays: Sample stability for a new pre-analytical protocol for fresh CSF

Amyloid beta 1-42 (Aβ42), tau phosphorylated at threonine-181 (p-tau181), and total tau (t-tau) are cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease diagnosis.

We prospectively examined storage time, temperature, and freeze/thaw effects on Aβ42, p-tau181, and t-tau stability in fresh CSF samples using Elecsys^® CSF immunoassays.

All three biomarkers were stable at 2-8°C for ≤15 days, and -25°C to -15°C for ≤8 weeks, and after one freeze/thaw cycle. p-Tau181 and t-tau were also stable at 15-25°C for ≤8 days and at -25°C to -15°C for 12-15 weeks. Aβ42 recovery declined slightly after storage at 15-25°C for ≤8 days and -25°C to -15°C for 12-15 weeks, and one freeze/thaw cycle.

For optimal immunoassay performance, it is recommended to store CSF samples at 15-25°C for ≤5 days, 2-8°C for ≤15 days, and -25°C to -15°C for ≤8 weeks.

Cerebrospinal fluid (CSF) biomarkers aid in Alzheimer's disease diagnosis. Fresh CSF stored at 15-25°C for ≤5 days is optimal for Elecsys CSF immunoassays. Fresh CSF stored at 2-8°C for ≤15 days is optimal for Elecsys CSF immunoassays. Fresh CSF stored at -25°C to -15°C for ≤8 weeks is optimal for Elecsys CSF immunoassays.