Objective: The objective was twofold. The focus of the study was primarily to determine if the stress of a particularly difficult exam could cause students to lose the normal diurnal variation seen in human cortisol levels and secondarily, to validate the use of a competitive enzyme immunoassay for salivary cortisol.
Design: Physical therapy students enrolled in Research Design were asked to participate in the study by collecting baseline evening and morning salivary cortisols during what was regarded as a relatively stress free time in the Fall of 2009. The following spring, the same students were asked for samples the evening before and morning of their first Kinesiology test, traditionally a stressful time. Method validation was accomplished using instrumentation owned by the Medical Laboratory Science (MLS) Program and analysis was performed by MLS faculty and a second year MLS student.
Setting: Participants were enrolled in the College of Health Sciences at the University of Tennessee in Memphis. Sample collection and testing was performed in the student laboratory of the Medical Laboratory Science Program.
Participants: Physical therapy students in their first year of a three-year entry level doctorate program, DPT.
Results: This group of students did not lose their diurnal variation of cortisol. However, an unexpected finding was noted: the students' salivary cortisol specimen collected in the morning of the fall semester was significantly higher than the salivary cortisol specimen collected the morning of the test in the spring semester (p = .019). Method validation was successful demonstrating a strong correlation ( r = 0.915) when compared to the reference laboratory.
Conclusions: Cortisol diurnal variation was not lost in the study participants, but further studies should be performed due to the low percentage of students completing the study and the lack of demographic diversity. Even though the method validation in the student laboratory setting demonstrates that it is indeed possible to obtain the same excellent correlation as is seen in a clinical setting, the student laboratory is not CLIA certified, so assays can be performed for research use only.