Objectives: The purpose of this study is to investigate the possible underlying pathogenesis of erectile dysfunction (ED) without well-known etiology in young men under the age of 40 years.
Methods: 192 patients and 33 normal controls were enrolled. ED was evaluated by using the International Index of Erectile Function-5 (IIEF-5) questionnaire. Traditional cardiovascular risk factors, hormone levels, and vascular parameters were measured. Insulin resistance (IR) was measured by homeostasis model assessment (HOMA).
Results: Patients with ED had significantly higher levels of systolic blood pressure (SBP), high-sensitivity C-reactive protein (Hs-CRP), high Insulin resistance index (HOMA-IR) and carotid intima-media thickness (IMT), compared with controls. The brachial artery endothelium-dependent flow-mediated vasodilation (FMD) values were significantly lower in ED patients. By multivariate logistic regression analysis, FMD, SBP, Hs-CRP and HOMA-IR were significantly associated with ED. In receiver-operating characteristic (ROC) analysis, FMD was a significant predictor of ED (area under the curve (AUC) 0.933, p < 0.001). The cutoff value of FMD <10.4 % had sensitivity of 81.3 % and specificity of 100 %. HOMA-IR was also proven to be predictor of ED (AUC of HOMA-IR 0.759, p < 0.001).
Conclusions: ED may be the first clinical sign of endothelial dysfunction and a clinical marker of cardiovascular and metabolic diseases. Subclinical endothelial dysfunction and insulin resistance may be the underlying pathogenesis of ED in young patients without well-known etiology. Measurement of FMD, HOMA-IR can improve our ability to predict and treat ED, as well as subclinical cardiovascular disease early in young men.