A simple method for measuring long-term integrated testosterone levels in men

Steroids play multiple roles in the regulation of development, physiology, reproduction, and behavior. Measuring circulating steroids is especially challenging since concentrations are extremely labile, responding to stressors within minutes. Matrices that integrate long-term steroid levels are therefore valuable as biomarkers of baseline, as well as chronic steroid exposures. Here we report on a simple method to extract and measure accumulated testosterone from human fingernails using commercial EIA kits. Further, we demonstrate known human testosterone sex and age trends. Thus, this method is a potential tool for biomonitoring endogenous as well as exogenous steroid exposure.