Are there symptom-specific testosterone thresholds in aging men?

OBJECTIVE To study the association between specific clinical symptoms (e. g. low libido and erectile dysfunction) and testosterone levels and age in order to define symptom-specific testosterone thresholds. MATERIALS AND METHODS Serum samples for testosterone determination were obtained from 675 healthy men. Participants underwent urological examination and completed the Aging Males Symptoms scale, the Beck Depression Index and the International Index of Erectile Function. Overall scores and those from individual questions from the questionnaires were evaluated. Testosterone levels in men with symptoms were compared with those in men without symptoms. The risks of clinical symptoms were evaluated using univariate, multiple multinomial regression analyses and Bonferroni correction. RESULTS Significant associations between testosterone levels and a number of androgen deficiency symptoms were seen at testosterone levels of 13.5-14.4 nmol/L, but multiple logistic regression analysis revealed confounding effects with age. Symptoms such as loss of libido, lack of vigour and sexual dysfunction were associated with age rather than with testosterone. Erectile dysfunction was reported at testosterone levels between 14.65 nmol/L and 14.8 nmol/L, but was again significantly associated with age rather than testosterone levels. The severity of symptoms significantly increased with decreasing testosterone levels using univariate analysis, but only the relationship with psychological symptoms remained significant after Bonferroni correction. CONCLUSION In aging males, androgen deficiency symptoms were reported at normal levels of testosterone, but age was an important confounder. Symptom-specific testosterone thresholds could not be defined.