Osteoprotegerin, Fibroblast Growth Factor 23, and Vitamin D3 Levels in Male Patients with Hypogonadism

Cardiometabolic disorders and osteoporosis are prevalent in patients with hypogonadism. Osteoprotegerin (OPG) and fibroblast growth factor-23 (FGF-23), are co-secreted from bones and vascular endothelium, regulating bone mineral metabolism and vascular functions. Vitamin D is another hormone with dual effects on bone and vascular metabolism. The aim of this study was to search for any difference between the serum levels of OPG, FGF-23, and vitamin D in patients with hypogonadism and the healthy controls. We also aimed to search for any relationship between these parameters and endothelial dysfunction or insulin resistance. Forty-nine male patients with congenital hypogonadotropic hypogonadism (CHH) (mean age 20.71 +/- 1.75 years) and 43 BMI matched healthy male subjects (mean age 21.37 +/- 1.04 years) were enrolled. OPG, FGF-23, vitamin D, and asymmetric dimethylarginine (ADMA) levels were measured from the fasting serum samples. The insulin sensitivity was estimated by homeostatic model assessment-insulin resistance (HOMA-IR) formula. Triglycerides, insulin, HOMA-IR, and ADMA levels in the patient group were significantly higher than the values of the control group (p=0.014, p=0.002, p=0.003, p<0.001, respectively). The OPG, FGF-23, and vitamin D levels of the patients were not significantly different from the healthy controls. In addition, these markers were not correlated to ADMA or HOMA-IR levels. The results show that young and treatment naive subjects with CHH have endothelial dysfunction and insulin resistance when compared to their healthy counterparts. However, the OPG, FGF-23, and vitamin D levels were similar in the 2 groups. In addition, these parameters are not significantly related to the endothelial functions or insulin resistance in these subjects.