501 citations
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October 2008 in “Psychoneuroendocrinology” Hair cortisol levels can show increased stress during late pregnancy but only for up to six months.
Distal hair cortisol is not a reliable measure of early pregnancy cortisol levels.
July 2022 in “Research Square (Research Square)” Hair analysis can somewhat track past testosterone levels but is influenced by factors like hair washing, growth rate, sex, and hair color.
8 citations
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August 2018 in “Drug testing and analysis” EtG levels in hair decrease significantly after one month of alcohol abstinence.
30 citations
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March 2012 in “Journal of Analytical Toxicology” THCCOOH levels in hair decrease from root to tip and don't match well with self-reported cannabis use.