Diagnostic significance of salivary testosterone measurement revisited: using liquid chromatography/mass spectrometry and enzyme-linked immunosorbent assay

Background & Objectives: The use of saliva as a material for screening biomarkers has several advantages in the study of large research populations. Since testosterone is not bound to protein in saliva, salivary testosterone determination provides an excellent approach for the evaluation of serum bioavailable or free testosterone. Liquid chromatography/mass spectrometry (LC-MS) has been considered to be a gold standard for estimating serum total testosterone levels in male serum. Our objective was to evaluate the reliability of salivary testosterone levels as measured by LC-MS. We also investigated the association between salivary testosterone measured by LC-MS and that measured by enzyme-linked immunosorbent assay (ELISA) in order to evaluate the clinical application for ELISA measures. Methods: The study involved 51 healthy male volunteers (median age = 57 years old; range = 30-85 years) and 29 patients with late-onset hypogonadism (LOH) (median age = 65 years; range = 55-78 years) in order to include a wide range of testosterone levels (median age of all subjects = 65 years; range = 30-85 years). Serum total testosterone was measured using LC-MS, and sex hormone binding globulin (SHBG) by immunoradiometric assay. Serum free testosterone and bioavailable testosterone levels were calculated using an international formula. Salivary testosterone levels were measured using LC-MS and ELISA. Results: Salivary testosterone levels measured by LC-MS were in accordance with calculated serum free testosterone levels (r = 0.655, p < 0.001, y = 0.91x+27.04; where x is the salivary testosterone measured by LC-MS and y is the calculated free testosterone). Salivary testosterone measured by LC-MS and ELISA showed a strong correlation (r = 0.808, p < 0.001). Conclusion: Salivary testosterone measured by LC-MS and ELISA is a non-invasive, reliable substitute for serum calculated free or bioavailable testosterone. Considering its cost advantage and technical convenience, ELISA for salivary testosterone is now recommended for the purpose of screening the androgen bioavailability level especially in a large population-based study. (C) 2008 WPMH GmbH. Published by Elsevier Ireland Ltd.