Evidence for Alteration in Serum Concentrations of Leptin in Infertile Men Categorized Based on BMI

The aim of this study is to compare serum and seminal level of leptin in the context of infertility in men according to BMI. We also investigated the possible correlation of circulating level of leptin with fertility indices.

This case-control study was conducted on 193 men who consecutively attended a referral outpatient infertility clinic of Shariati Hospital. The leptin level in serum and seminal plasma were quantified by enzymelinked immunosorbent assay (ELISA) in fertile men (n = 95) and infertile men (n = 98). All participant were ageand BMI-matched. Semen was also analyzed in terms of volume, sperm concentration (106/mL), motility (%), and morphology in all subjects prior to study. Based on body mass index (BMI) value, all participants were divided into three groups; lean, body mass index (BMI) 19 - 24.99kg/m2, overweight, BMI 25 - 29.99 kg/m2, and obese BMI ≥ 30 kg/m2.

Fertile and infertile men were significantly compatible regarding sperm concentration; however, we found no significant difference in case of the leptin level in serum and semen between the two studied groups (p-value = 0.5 and p-value = 0.1, respectively). In the infertile group, serum leptin level was significantly correlated with BMI (r = -0.291; p = 0.004 for the fertile group). Moreover, there was an inverse correlation between serum leptin level and sperm motility (r = -0.241; p = 0.014) in infertile men. Interestingly, among the infertile group, we observed an augmented serum level of leptin in obese men in comparison with lean (p = 0.009) and overweight (p = 0.07) individuals.

Our findings along with other studies support this concept that increased BMI is of clinical relevance in the context of infertility in men since our data revealed an inverse correlation between seminal leptin level and BMI in infertile men. Specifically, alteration in serum level of leptin was obviously different in infertile men in terms of overweight and obesity. However, more studies are required to unravel obscure issues in this regard.