Endocrine Abstracts

: In community-dwelling men, salivary testosterone (Sal-T) concentrations are thought to represent tissue hormone levels and correlate strongly with serum free-T levels. Measurement of salivary glucocorticoid concentrations is a non-invasive and objective means of assessing cortisol exposure in users and non-users of hydrocortisone therapy. We assessed relationships of Sal-T with transdermal testosterone replacement therapy (TD-TRT) and with markers of testosterone exposure. In 40 men aged 50.7 (±13.9) years who were attending a university hospital endocrinology clinic, we measured serum and salivary androgen concentrations by immunoassay and liquid chromatography tandem mass spectrophotometry (LC-MS/MS) respectively. In our unit, TD-TRT (Tostran 2% Gel at an initial dose of 30–60 mg of testosterone once daily) is offered to men with sexual symptoms and low fasting serum testosterone (Ser-T) concentrations on at least two consecutive occasions. Ser-T concentrations did not differ between users (n=23) and non-users (n=17) of TD-TRT (16.6±10.2 vs 11.4±4.4 nmol/l, P=0.131). Sal-T concentrations, however, differed greatly (17.14±15.25 vs 0.23±0.15 nmol/l, P<0.001) as did salivary androstenedione (Sal-A4) concentrations (2.57±4.50 vs 0.17±0.04 nmol/l, P<.001) and Sal-T/Sal-A4 (16.26±14.25 vs 1.45±0.94, P<0.001). Haematocrit and serum prostate specific antigen concentrations (PSA) did not differ significantly between the two groups (0.44±0.05 vs 0.43±0.05 l/l, P=0.563 and 1.06±0.66 vs 0.79±0.53 ng/ml, P=0.170 respectively). With TD-TRT, there was a rise in blood testosterone (4.7±4.2 to 7.9±5.7 nmol/l, P=0.162), haematocrit (0.42±0.05 to 0.44±0.04 l/l, P=0.049) and PSA (0.68±0.33 to 1.06±0.76 ng/ml, P=0.021) levels. Two hours after a dose of TD-TRT, Ser-T rose modestly (10.5±13.2 to 16.6±11.0 nmol/l, P=0.003) and Sal-T rose tremendously (7.7±8.1 to 17.0±16.9 nmol/l, P=0.004). Despite normal Ser-T, haematocrit and PSA concentrations, Sal-T concentrations are 75-fold greater than normal in men using TD-TRT. This is unlikely due to contamination (Sal-A4 concentrations are also high) and may be due to a conduit between skin, the lymphatic system and salivary ducts. Measurement of Sal-T is unlikely to be useful in the monitoring of men using TD-TRT.