The effects of collection and storage conditions in the field on salivary testosterone, cortisol, and sIgA values

Aim: To determine if field-typical storage and collection conditions are related to salivary testosterone (T), cortisol (cort) and secretory immunoglobulin A (sIgA) as measured using commercially available kits. Subjects and methods: This study assessed whether storage time (∼6 months to 1.5 years) at −35 °C impacted levels of the measured biomarkers (n = 10,247 samples). For a sub-set of T samples (n = 2954), we also evaluated the impact of collection conditions, such as time spent at room temperature in participants’ homes (0–39 hours) and time spent in coolers (0.3–10 hours) in transit. Results: T was unrelated to storage and collection variables and there was no evidence of reduced sample fidelity at longer storage times. Cort samples stored at −35 °C for longer had significantly lower values, but the effect was small (β = −0.003 nmol/L/day, SE <0.001, p = 0.005). sIgA trended higher with longer storage at −35 °C (β = 0.84 µg/mL/day, SE = 0.45, p = 0.063). Collection and storage time variables did not improve the fit of any of the models except the one that evaluated cortisol. Conclusions: Salivary T was unaffected by extended storage at −35 °C and only a weak relationship was found between storage time and salivary cort or sIgA. Findings underscore the robustness of these biomarkers under field-typical freezer storage conditions.