Low testosterone level of middle-aged Japanese men - the association between low testosterone levels and quality-of-life

摘要

Background: Late-onset hypogonadism (LOH) is due to age-related steep declines in free testosterone levels in middle age. LOH can induce a variety of signs and symptoms that deteriorate the quality-of-life (QOL) of middle-aged men. This study examined the circadian rhythm of salivary testosterone levels in three age cohorts: 20s-30s, 40s-50s, and 60s+ to investigate the association between QOL and testosterone levels in adult Japanese men.Subjects and Methods: Eighty-one healthy male Japanese volunteers and 20 LOH patients in their 40s-50s were recruited. Their salivary testosterone levels were measured as were independent variables including Body Mass Index (BMI) and smoking rates. The SF-36 v2 was used as the health-related questionnaire to evaluate QOL. Saliva samples were collected at 2-hour intervals between 9:00 am and 9:00 pm. Salivary testosterone levels were determined using an enzyme-linked immunosorbent assay (ELISA: Demeditec Diagnostics, Germany).Results: There were no significant differences in BMI and smoking rates among the three healthy groups. However, scores from the SF-36 related to body pain were significantly lower in the 40s-50s cohort than in the 20s-30s group. The mean salivary testosterone levels in the 40s-50s group were the lowest at any point of time, except for 9:00 am among all healthy cohorts, and were similar to those of LOH patients. A circadian rhythm was seen in salivary testosterone levels in the 20s-30s and 40s-50s groups, whereas it was lost in the 60s+ group and in LOH patients.Conclusion: Middle-aged Japanese men had the lowest levels of salivary testosterone and the worst QOL scores in relation to body pain, which may affect their overall QOL.