Testosterone levels increase following bariatric surgery - validation of preceding literature in a large-scale population analysis.

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 ² . Post-surgery, 45% (31 men) achieved eugonadal status, while 55% (38 men) continued to have low T levels. A comparison between the post-surgery eugonadal cohort and the persistent low T cohort revealed that the former had higher pre-surgery serum T levels (235 ± 71 ng/dL vs. 184 ± 80.4 ng/dL, p = 0.007), a higher pre-surgery body mass index (45.5 ± 4.5 kg/m ² vs. 41.1 ± 11.5 kg/m ² , p = 0.041), and a significantly greater reduction in body mass index post-surgery (7.3 ± 7.2 kg/m ² vs. 2.0 ± 12.8 kg/m ² , p = 0.04). Notably, the increase in T was significantly higher in the eugonadal cohort compared to the persistent low testosterone cohort (257 ± 143 ng/dL vs. 95 ± 178 ng/dL, p < 0.0001).
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.
(© 2024 The Author(s). Andrology published by Wiley Periodicals LLC on behalf of American Society of Andrology and European Academy of Andrology.)