Steatosis indices and penile vascular health: a metabolic association linking liver and vascular phenotypes

Objective: To examine the association between non-invasive steatosis indices—Fatty Liver Index (FLI), Hepatic Steatosis Index (HSI), and Dallas Steatosis Index (DSI)—and Penile Color Doppler Ultrasonography (PCDU) derived parameters of vasculogenic erectile dysfunction, including peak systolic velocity (PSV) and intima–media thickness (IMT). Methods: In this retrospective study, 96 men evaluated for erectile dysfunction (ED) underwent dynamic PCDU after intracavernosal alprostadil injection. Clinical, biochemical, and metabolic data were collected. Associations between steatosis indices and PCDU parameters were analysed. Multiple regression identified independent predictors of PSV, and ROC analysis assessed the performance of FLI in detecting reduced PSV (< 35 cm/s). Results: Reduced PSV was observed in 24% of participants and was associated with older age, higher FSH and LH levels, lower total and free testosterone, and higher FLI values, while HSI and DSI did not differ between groups. FLI correlated inversely with PSV (R = − 0.305; p = 0.003). In multivariable analysis, only FLI (p = 0.031) independently predicted PSV. ROC curve analysis indicated that an FLI threshold ≥ 67.6 identified reduced PSV with 56% sensitivity and 82% specificity. Conclusions: FLI is independently associated with impaired penile arterial inflow and may represent a practical, non-invasive marker of vascular andrological risk. These findings suggest that FLI could assist early risk stratification in men with ED.