The Impact of Obesity on Serum Testosterone Levels and Semen Quality in a Population of Infertile Men

Abstract

Introduction: Multiple factors contribute to male infertility, with hypogonadism and low testosterone levels possibly affecting fertility in different aspects. This study focused on factors for low testosterone in infertile male patients. Materials and Methods: We retrospectively collected data of patients who were diagnosed with infertility and visited the National Taiwan University Hospital from January 2015 to October 2017. Patients' weight and height, basic blood test results, sperm analysis, and sex hormone profile were recorded. Patients diagnosed with obstructive azoospermia, particularly absence of bilateral vas deferens, those who received a vasectomy or orchiectomy, and patients diagnosed with cancer undergoing chemotherapy or radiotherapy were excluded. Pearson's correlation test was applied for detecting associating factors for serum testosterone. Multivariate linear regression was used for detecting independent factors predicting serum testosterone. An independent t-test was used to analyze continuous variables, and the Chi-square test was used for categorical variables. Results: Two hundred and forty-seven patients had serum sex hormone profile and semen profile recorded. The mean age was 36.48 ± 8.68 years. Pearson's correlation test showed that serum testosterone was correlated with serum triglyceride, total cholesterol, fasting blood sugar, and body mass index (BMI). However, multivariate linear regression showed BMI (P = 0.001) and smoking (P = 0.029) to be independent factors predicting serum testosterone. On comparing sex hormone profile and semen profile between obese (BMI ≥30), overweight patient (BMI ≥25, <30), and nonoverweight patients (BMI <25), (i) serum testosterone was significantly lower in the obese and overweight group comparing to nonoverweight group (nonoverweight: 3.61 ± 1.63 ng/ml vs. overweight: 2.87 ± 1.27, P = 0.001; nonoverweight: 3.61 ± 1.63 vs. obese 2.89 ± 1.59, P = 0.035). Follicle stimulating hormone, luteinizing hormone, and prolactin did not differ significantly between the groups. No significant difference in sperm parameters, namely the total sperm count, sperm concentration, total sperm motility, and morphology, was observed between the groups. Conclusion: In the infertile Taiwanese male population, obese patients (BMI ≥ 30) and overweight patients (BMI ≥25) had a significant lower serum testosterone than the nonoverweight patients. Body weight control and treatment of metabolic syndrome, and diabetes could improve serum testosterone levels.