The definition and diagnosis of functional hypogonadism (FH) remains challenging due to the nonspecific nature of symptoms and the inconsistency in normal testosterone thresholds. We conducted this single-center cross-sectional study on medical records of men aged 18 and above undergoing annual health check-ups to evaluate the correlation of age and metabolic components with testosterone. A total of 5,374 healthy men were included in the analysis. Total testosterone levels peaked at 18 years and gradually declined to age 40, followed by a mild increase. Based on the American Urology Association guideline, age-specific cutoffs for low testosterone were 14.61 nmol/l, 12.74 nmol/l, 12.70 nmol/l, and 13.98 nmol/l for those under 30, 30-40, 40-50, and over 50 years old respectively. Triglyceride - Glucose index showed a consistent negative correlation with testosterone across all age groups. In conclusion, testosterone levels demonstrated an age-related decline in early adulthood but a potential increase thereafter among healthy Vietnamese men. Metabolic components, rather than aging, had a consistent negative correlation with testosterone. Age-specific cutoffs for low testosterone may improve the detection of functional hypogonadism.
Keywords: Testosterone; aging men; diagnostic threshold; functional hypogonadism; sexual dysfuntion.