BACKGROUND: The effects of bariatric surgery on testosterone levels in men with obesity and hypogonadism have not been thoroughly explored yet. OBJECTIVES: To investigate the possible effects of bariatric surgery on T levels in obese hypogonadal men by comparing T levels before and after surgery using a comprehensive claims database. MATERIALS AND METHODS: The TriNetX US Collaborative Network database was used to identify men ages 18-80 who underwent a bariatric procedure and had a serum T value of <
350 ng/dL prior to surgery. Men who received testosterone therapy before/or after surgery were excluded. We conducted a retrospective self-matched cohort analysis to examine the difference in serum T levels before and after bariatric surgery. A sub-analysis was carried out to explore differences between men who reached eugonadal status or maintained low T levels following surgery. Descriptive statistics detailed sociodemographic and clinical characteristics, with continuous and categorical data compared using unpaired t-tests and chi-square analysis, respectively. Changes in T levels and body mass index (BMI) before and after surgery were compared using an unpaired t-test with a <
0.05 set for significance. All analyses were conducted using the TriNetX platform which utilizes both Python and R software. RESULTS: The study analyzed 69 hypogonadal men who underwent bariatric surgery and had T levels assessed before and after the procedure. The mean (standard deviation) pre-surgery serum T level was 208 ± 79 ng/dL, which post-surgery increased to 371 ± 164 ng/dL, marking an average increase of 163 ± 164 ng/dL. Likewise, the mean (standard deviation) body mass index decreased from 42.9 ± 9.0 to 38.8 ± 5.7 kg/m CONCLUSION: This study provides evidence of bariatric surgery's positive effect on serum T levels in obese men with baseline low T. Almost one out of two men with low T reached normal T levels after bariatric surgery. As the most comprehensive study to date, it validates and substantiates previous work suggesting that weight loss can improve T levels physiologically.