Rapid noninvasive measurement of hormones in transdermal exudate and saliva

Experiments were conducted in both sheep and humans to evaluate techniques for rapid sampling and measurement of testosterone, insulin, 17-β estradiol, cortisol and glucose collected in saliva or transdermal exudate. Ultrasound and an electric current facilitated the latter collection. All but insulin were successfully measured in saliva, under resting conditions, and the measured hormones correlated best with blood levels 20-40 min prior to the saliva collection. With imposition of, and recovery from, an exercise stress, this correlation was weakened irrespective of considering the time lag between blood measures during this period and subsequent changes in saliva values. Provided an initial transdermal flux was established, all the hormones and glucose were successfully measured in the transdermal exudate at levels correlating with blood measures at the time of collection, and this held across stressor application and recovery. The transdermal exudate sampling and measurement apparatus is relatively portable, enabling noninvasive collection and analyte measurement, rapidly, at the site where the experiment is being conducted with minimal interference to subjects. This potentially offers a tool of considerable value to endocrine studies.