Salivary testosterone reference intervals for adult women and men

Objectives: Testosterone is increasingly being measured in saliva due to the ease of collection, which puts a lower burden on patients and facilitates measurement in clinical and behavioral studies. Although the robustness of measuring testosterone in saliva using immunoassays has been questioned, liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS)-based tests have been developed as a sensitive and specific alternative. To correctly interpret salivary testosterone concentrations determined by LC-MS/MS, reference intervals are required. Only limited studies reporting reference intervals for salivary testosterone are available, especially for women and evening concentrations. Thus, we aimed to establish reference intervals for salivary testosterone determined by LC-MS/MS for adult women and men in the morning and evening. Methods: Testosterone was determined using LC-MS/MS for 223 women and 212 men from samples collected in the morning (directly after waking) and in the evening (prior to bed). Results: Reference intervals for women were 5.5–49.0 and <27.5 pmol/L for the morning and evening, respectively. For men, reference intervals were 81.4–375.6 and 47.6–251.0 pmol/L for the morning and evening, respectively. Furthermore, sensitivity analysis revealed only minor influence of factors such as alcohol use, smoking, obesity, and, for women specifically, oral anticonception and pregnancy, with results within the confidence intervals of the general reference interval. Conclusions: We here report on reference intervals for salivary testosterone for adult women and men in the morning and evening. These are the first LC-MS/MS salivary testosterone reference intervals determined with sufficient participants according to CLSI EP28-A3c, strengthening the interpretation of salivary testosterone concentrations for both clinical and research applications.