[LONGITUDINAL CHANGES OF FREE TESTOSTERONE LEVELS AND SEXUAL FUNCTION IN JAPANESE MEN EVALUATING TWO CROSS-SECTIONAL COMMUNITY-BASED STUDIES].

(Purpose) We conducted cross-sectional studies two times, in 1992 and 2007 and investigated the longitudinal changes of fT levels and sexual function by comparing the results. (Methods) In 1992 and 2007, we conducted cross-sectional surveys about lower urinary tract symptoms and sexual function in male inhabitants aged 40 to 79 years in Shimakaki village, Hokkaido. Comparing the results of these surveys, we analyzed longitudinal changes in fT levels and sexual function. FT levels were measured by radioimmunoassay and sexual function was evaluated using a validated questionnaire. (Results) A total of 123 inhabitants participated in the both surveys. The average age at the initial survey was 57.2 years.Complications causing sexual dysfunction were observed in 43 participants (35%) and 75 participants (61%) in the first and second surveys, respectively. Average fT levels were 12.9 pg/ml and 4.4 pg/ml in the first and second surveys, respectively. Linear approximations of fT (Y) using age (X) were Y = -0.12 X+19.6 and Y = -0.10 X+11.6, for the first and second surveys, respectively. Although decreased fT levels with aging were comparable in both surveys, fT levels were lower in the second survey than in the first survey. There was no significant association between fT levels and sexual function. (Conclusions) The fT levels at the time of the second surey were lower than those in the first survey. The fT level has no significant association with sexual function.