The relationship of serum testosterone to erectile function in normal aging men

PURPOSE: We evaluated the variation in serum testosterone in normal aging men and its relationship with erectile function. MATERIALS AND METHODS: In a study that was not community based and during a free screening program for prostate cancer 1,071 men were invited to complete a sexual activity questionnaire, that is the abridged 5-item version of the International Index of Erectile Function (IIEF-5), as a diagnostic tool for erectile dysfunction. Possible scores on the IIEF-5 are 1 to 25 and erectile dysfunction was classified into 5 categories based on the scores, namely severe-1 to 7, moderate-8 to 11, mild to moderate-12 to 16, mild-17 to 21 and none-22 to 25. Serum total testosterone was measured between 8:00 and 10:00 a.m. in all men. RESULTS: Of the 1,071 men 965 (90.1%) were included in this study, of whom 88% were white and 12% were black. Mean age was 60.7 years. In this sample the prevalence of all degrees of erectile dysfunction was estimated to be 53.9%. The degree of erectile dysfunction was mild in 21.5% of cases, mild to moderate in 14.1%, moderate in 6.3% and severe in 11.9%. According to age the erectile dysfunction rate was 36.4% in the 40 to 49, 42.5% in the 50 to 59, 58.1% in the 60 to 69, 79.4% in the 70 to 79 and 100% in the 80 years and older groups (p <0.05). The variation in mean serum total testosterone in the age groups was not statistically significantly different (p >0.05). Pearson coefficients of age and total testosterone did not reveal any significant correlation (r = 0.00376, p = 0.907), similar to IIEF-5 score and total testosterone (r = 0.0163, p = 0.612). However, analysis of the variables IIEF-5 and age showed a statistically significant inverse or negative relationship (r = -0.3449, p <0.05). CONCLUSIONS: Erectile dysfunction showed a clear association with aging but no consistent correlation of total testosterone with erectile condition was identified.