The role of leptin in reproductive dysfunction in patients with varicocele: a systematic review and meta-analysis

The mechanism of leptin's role in female infertility has been demonstrated, however, the relationship between it and infertile patients with varicocele has yet to be determined. This study aimed to evaluate role of leptin in reproductive dysfunction in patients with varicocele.

A computerized literature search was independently conducted by two researchers in PubMed, EMBASE, Web of Science, ScienceDirect, and Cochrane Library up to July 2025. The search terms were as follows: 'leptin', 'varicocele' and 'infertility'. The Newcastle-Ottawa Scale was used to assess the quality of the included studies. The meta-analysis was performed using Review Manager version 5.1 and R version 4.0.5.

36 studies were retrieved and 5 studies were included for meta-analysis. We found that the expression of leptin in seminal plasma in infertile patients with varicocele were significantly higher than controls (SMD, 2.72; 95%CI, 1.05-4.39; I2 = 96%, p=0.001). In contrast, the serum leptin levels did not show statistically significant differences (SMD, 1.26; 95%CI -0.73-3.26; I2 = 96%, p=0.21) between patients and controls. Seminal plasma leptin levels had a moderate negative correlation with sperm concentration (r=-0.54; 95%CI, -0.77 - -0.19; p<0.01). Additionally, seminal plasma leptin levels had a strong negative correlation with sperm progressive motility (r=-0.71; 95%CI, -0.93 - -0.09; p<0.01).

The expression of leptin in seminal plasma was significantly higher in infertile patients with varicocele. Seminal plasma leptin levels had a negative correlation with sperm concentration and progressive motility. Leptin in seminal plasma seemed to have a negative effect on the reproductive function of patients with varicocele.