Epicardial fat: the role of testosterone and lipid metabolism in a cohort of patients with Klinefelter syndrome

Context: Klinefelter syndrome (KS), in which subjects have additional copies of X chromosomes, is the most common male sex chromosome abnormality, with a prevalence of 1 in 660 and an incidence of about 1 in 500–700 newborns. Its sign and symptoms include infertility, generally low testosterone levels, and an increased prevalence of obesity and metabolic syndrome. Epicardial fat thickness (EFT) reflects visceral adiposity rather than general obesity. Objective: The aim of this study was to analyze echocardiographic EFT in a cohort of patients with KS in comparison with non-obese and obese euploid controls, and to evaluate its correlation with biochemical parameters. Design, setting and participants: Two hundred and twenty-one KS patients referred to our Rare Endocrine Diseases clinic and 77 age-matched controls underwent Doppler echocardiography and a full investigation of anthropometric and body composition, Serum levels of total testosterone (T), estradiol (E2), sex hormone binding globulin (SHBG), fasting plasma glucose, insulin, cholesterol and triglycerides were obtained. All participants underwent dual energy X-ray absorptiometry (DEXA) scan to assess truncal body fat (TrBF). Main outcome measure: EFT, body composition and metabolic parameters in KS patients and how they are affected by genotype. Results: EFT was greater in KS patients than in healthy non-obese (NOb) controls, but lower than in obese (OB) controls. When KS patients were divided into groups (hypogonadal; eugonadal; receiving testosterone replacement therapy [TRT]), EFT was greater in hypogonadal patients than in NOb controls and eugonadal patients, but showed no difference from the OB controls or TRT patients. Hypogonadal patients showed increased TrBF in comparison with NOb controls and eugonadal and TRT patients, and similar TrBF to OB controls. As expected, there was a strong correlation between BMI and EFT in both KS patients and controls (P < 0.0001). In contrast, there was a strong inverse correlation between testosterone and EFT in the control group, but not in KS patients. EFT was significantly correlated with TrBF in both populations (P < 0.0001). Multivariate analyses showed that the major determinants of both EFT and TrBF were BMI and the presence of KS itself. Testosterone and triglycerides were not included as variables in the models. Conclusion: EFT in hypogonadal KS subjects was similar to that of the obese eugonadal controls. Even though there was a direct correlation between BMI and EFT in both populations, the influence of TrBF on EFT was stronger. The presence of the supernumerary X chromosome appeared to be one of the strongest determinants of EFT and TrBF, independent of testosterone levels.