THE RELATIONSHIP BETWEEN SALIVARY CORTISOL CONCENTRATIONS IN FROZEN VERSUS MAILED SAMPLES

Saliva, popular for the measurement of cortisol concentrations, can be easily and painlessly obtained, so that study participants or medical patients may collect their own samples. This raises the question of w hether cortisol concentrations are stable if samples are mailed unfroz en. Seventeen adult subjects (five males, 12 females, mean age = 27.82 , SD = 7.55) participated in this study. One saliva sample From each s ubject was split. Half were frozen within 1 h. The other was exposed t o conditions that would mimic a postal trip, including wide variations in temperature and movement over 5 days. A statistically significant positive correlation between cortisol concentration in the frozen and nonfrozen saliva samples was found (R-2 = 0.92, p <.001). A paired t-t est revealed no significant difference between samples (t(16)= 1.56, n .s.). This indicates that cortisol concentrations are stable during ex tended periods without freezing when exposed to widely varying tempera tures and movement. (C) 1998 Elsevier Science Ltd. All rights reserved .