Endocrine Abstracts

Context: In population and psychosocial studies, saliva becomes increasingly popular, mainly due to its non-invasive collection methods and availability of free hormone fractions. However, few studies have evaluated the impact of collection devices on steroid hormone analysis; and none with the currently used methods.

Objective: The aim of this pilot study was to minimize pre-analytical errors based on sample collection methods.

Methods: We tested two saliva collection methods: chewing on a cotton swab (Salivette, Sarstedt) and passive drooling. Thirty healthy males with a median age of 27 years (range 19–65 years) participated. Morning saliva and serum samples were simultaneously collected after overnight fasting. Serum and salivary cortisol, serum total testosterone and SHBG were analyzed by electrochemiluminescent immunoassay (ECLIA, Roche Modular) and transcortin by a RIA. Serum free cortisol and testosterone were calculated. Salivary testosterone was determined using liquid chromatography–mass spectrometry.

Results: Strong positive correlations between the cotton-based and the passive drooling collection method were observed for cortisol as well as testosterone (respectively r=0.70 and r=0.88). For cortisol, we observed a mean positive bias of 65% for passive drooling versus Salivette. In addition, cortisol determined on passive drooling samples correlated much worse with calculated free cortisol than cortisol analyzed on the cotton samples (respectively r=0.34 versus r=0.70). However, for testosterone passive drooling correlated well with the calculated free fraction (r=0.66). A positive bias of 21% for testosterone collected by passive drooling versus Salivette was observed. In contrast to earlier reports, we found no artefactually high testosterone results with the cotton-based collection method.

Conclusion: Our findings have important implications for the use and potential misuse of saliva collecting methods. Cotton swabs and passive drooling both seem adequate saliva collection methods for the analysis of testosterone, but passive drooling does not appear suitable for cortisol analysis.