Potential predicting function of betatrophin in patients with polycystic ovary syndrome and it's relationship with 25-hydroxy vitamin D3

Abstract

Objective Through the detection of the levels of serum betatrophin, anthropometric and biochemical indices, to determine the alteration of betatrophin levels in patients with polycystic ovary syndrome (PCOS) and the relationship between betatrophin levels and metabolic indexes such as 25-hydroxy vitamin D3 [25 (OH) D3]. Methods The study group was composed of 24 women with PCOS and 20 age-matched healthy women as controls. Following general physical examination of the subjects, anthropometric measurements were performed (height, weight, waist circumference, hip circumference). Body mass index (BMI) and waist-hip ratio were calculated; 25 (OH) D3, Ca2+, fasting blood glucose, fasting insulin, triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) were also measured and homeostasis model assessment of insulin resistance (HOMA-IR) were evaluated in all subjects. Serum betatrophin levels were examined with an enzyme-linked immunosorbent assay (ELISA). Using independent sample T test to compare the differences between groups, the linear correlation analysis was performed to study the correlation of betatrophin with anthropometric and biochemical indices, the influencing factors of betatrophin were analyzed by multiple linear regression. Results Circulating betatrophin levels [(0.341±0.034) ng/ml vs. (0.810±0.162) ng/ml, t= 4.271, P<0.001] and HDL-C [(1.014±0.321) mmol/L vs. (1.419±0.287) mmol/L, t= 2.218, P<0.05] significantly decreased in women with PCOS compared with controls, and BMI [(27.691±4.392) kg/m2vs. (23.310±4.781) kg/m2, t=-2.073, P<0.05], fasting blood glucose [(5.950±0.411) mmol/L vs. (4.883±0.314) mmol/L, t=-2.142, P<0.05], HOMA-IR [(4.946±0.741) vs. (3.387±0.397), t= -2.493, P<0.05], triglycerides [(1.510±0.848) mmol/L vs. (1.037±0.402) mmol/L, t=-2.223, P<0.05], LDL-C [(3.431±0.479) mmol/L vs. (2.396±0.435) mmol/L, t=-2.433, P<0.05] were obviously increased. Moreover, there was a postive correlation between betatrophin and HOMA-IR (r= 0.425, P<0.05) as well as 25(OH)D3 (r= 0.577, P<0.05) and Ca2+ (r= 0.448, P<0.05), while the betatrophin was negatively related to BMI (r=-0.451, P<0.05), triglycerides (r=-0.454, P<0.05), LDL-C (r=-0.551, P<0.05). Circulating betatrophin levels were higher when 25 (OH) D3 levels were beyond 35 nmol/L in PCOS patients [(0.539±0.092) ng/ml vs. (0.199±0.031) ng/ml, t=3.072, P<0.001], and the multiple linear regression analysis showed that the main factors affecting the levels of betatrophin were BMI (OR=-0.260), HOMA-IR (OR=0.218), 25(OH)D3 (OR=0.238), and glycerol (OR=-0.162). Conclusion It is speculated that betatrophin may be a valuable predictive factor of PCOS because betatrophin is closely associated with insulin resistance, lipid metabolism disorders and the lack of 25-hydroxy vitamin D3 in PCOS patients. Key words: Polycystic ovary syndrome; Insulin; 25-hydroxy vitamin D3