The IGF1/FSH Ratio Correlates with Sperm Count and Testicular Volume

Abstract

BACKGROUND. Several studies have already investigated the relationship between IGF1 and semen parameters. However, clinical studies rarely concluded on the existence of a relationship between IGF1 and the sperm number, and whether the IGF1 serum levels have a practical value in the diagnostic work-up of patients with oligozoospermia is still unclear. OBJECTIVE. Molecular evidence reported that IGF1 and FSH belongs to the same molecular pathway. The aim of this study is to assess whether insulin-like growth factor-1 (IGF1)/follicle-stimulating hormone (FSH) ratio has an impact on testicular function and, specifically, on sperm number and testicular volume in a cohort of unselected men. METHODS. This is a cross-sectional study on 59 patients who attended the Seminology laboratory of the Division of Endocrinology of the University of Catania (Catania, Italy) for semen analysis. Data were analyzed to evaluate the relationships between IGF1 or IGF1/FSH ratio and sperm concentration, total sperm count (TSC), and testicular volume (TV). We also evaluated the occurrence of any difference in IGF1 and FSH serum levels and the IGF1/FSH ratio in patients with oligozoospermia and those with a TSC > 39 million/ejaculate. MAIN RESULTS AND ROLE OF CHANGE. Patients had a mean age of 31.0 ± 8.5 years. The mean FSH and IGF1 levels were 3.95 ± 2.55 mIU/mL and 232.59 ± 65.13 ng/mL, respectively. IGF1 serum levels did not correlate with sperm concentration, TSC, and TV. The IGF1/FSH ratio showed a positive correlation with sperm concentration (r = 0.408; p = 0.004), TSC (r = 0.468; p = 0.001), and TV (0.463; p = 0.002). Patients with oligozoospermia (Group 1, 23.7%, n = 14) had a significant lower IGF1/FSH ratio (57.9 ± 9.5 vs. 94.1 ± 8.7; p = 0.03) compared to those with TSC > 39 million/ejaculate (Group 2, 76.3%, n = 45). They did not differ significantly for neither IGF1 nor FSH serum levels. CONCLUSION. We found a positive correlation between the IGF1/FSH ratio and sperm concentration, TSC and TV. Furthermore, patients with oligozoospermia showed a significantly lower ratio compared to those with a normal TSC, while neither IGF1 nor FSH differed significantly in the two groups. Our results may reflect the existence of a molecular pathway to which IGF1 and FSH belongs. However, further studies are needed.