Hair cortisol and other hair analytes decline with storage over a one-year period: A systematic, within-subject investigation

Our findings demonstrate that extended storage duration adversely affects the quality of results for hair cortisol and cortisone as well as for other hair steroid and endocannabinoid analytes. Therefore, storage duration should be considered as a critical methodological factor when planning the study design and interpreting hair data. Analyzing hair samples within six months post sampling is recommended. Further, details on storage methods should be transparently reported in future research.