Background
Male hypogonadism is a clinical and biochemical syndrome that results from failure to produce adequate testosterone levels, normal sperm count, or both. Male hypogonadism may adversely affect multiple organ functions and quality of life. Vitamin D is a steroid hormone; the major action of vitamin D is linked to maintaining musculoskeletal health. However, several epidemiological studies have suggested extraskeletal benefits of vitamin D. There is an accumulating body of evidence which suggests that vitamin D is involved in reproductive and gonadal functions. Although some studies have demonstrated that vitamin D levels are positively associated with androgen levels and that vitamin D supplementation may increase testosterone levels, other studies have observed a U-shaped association of vitamin D and hypogonadism in middle-aged men, in contrast, other studies fail to find an association between vitamin D and testosterone especially in young healthy men after exclusion of other confounding factors. Thus, the aim of our study was to study the possible association of vitamin D status with male hypogonadism among different age groups.
Patients and methods
The study included 80 men. Group I included 40 male patients aged 20 to less than 45 years who were further subdivided into two subgroups: group Ia included 20 male patients diagnosed with hypogonadism and group Ib included 20 eugonadal men serving as a control. Group II: included 40 male patients aged 45–70 years subdivided into two subgroups: group IIa included 20 male patients diagnosed with hypogonadism and group IIb included eugonadal men serving as a control. Using enzyme-linked fluorescent assay technique, serum total testosterone (TT), 25-hydroxyvitamin D [25(OH)D], luteinizing hormone, follicle stimulating hormone, estradiol, and prolactin were assessed for all enrolled individuals. Sex-hormone-binding globulin (SHBG) was assessed using the electrochemiluminescence immunoassay technique. Free androgen index (FAI) was calculated using the equation [100×TT (nmol/l)/SHBG (nmol/l)].
Results
It was found that TT, FAI, and SHBG were lower in hypogonadal men versus eugonadal men in both groups, there was no significant statistical difference between hypogonadal men in groups I and II as regards TT and SHBG (=0.708, 0.124, respectively), whereas FAI was found to be significantly statistically lower in hypogonadal men aged 45–70 years as compared with hypogonadal men aged 20 to less than 45 years (=0.021). There was a high prevalence of vitamin D deficiency and insufficiency in both hypogonadal and eugonadal men in the four studied subgroups. 25(OH)D was not statistically different between subgroups in both groups (=0.681, 0.823, respectively), whereas 25(OH)D was significantly higher in hypogonadal men in group II versus hypogonadal men in group I (=0.037). 25(OH)D was found to be positively correlated with TT, FAI, and SHBG, but not to serum estradiol, prolactin. Correlation of 25(OH)D was stronger in hypogonadal men aged 45–70 years (=0.001) as compared with hypogonadal men aged from 20 to less than 45 years (=0.023).
Conclusion
Low vitamin D is associated with male hypogonadism across all age groups. This association is more pronounced in elderly hypogonadal men with vitamin D deficiency.