September 2023 in “Scientific reports” Segmental hair analysis can track testosterone over time but needs adjustments for sex, hair color, and washing frequency.
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.
May 2023 in “Frontiers in chemistry” Zolpidem shows up in hair from the top back of the head after one dose and fades over time, suggesting it gets into hair through blood and sweat.
20 citations
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October 2017 in “Drug testing and analysis” Drugs localize differently in hair strands based on their properties.
67 citations
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June 2013 in “Therapeutic drug monitoring” Wait 4-5 weeks after drug use before hair testing and cut hair into three segments to confirm single drug exposure.