Subclinical hypothyroidism (SH) is characterized by elevated serum thyroid-stimulating hormone (TSH) levels despite normal free thyroxine (FT4) concentrations. This study aims to evaluate the early hemodynamic shifts in the systemic circulation using high-resolution Doppler ultrasonography. A cohort of 42 subjects was analyzed to identify the correlation between TSH elevation and peripheral vascular resistance. The results indicate a statistically significant decrease in peak systolic velocity (PSV) and an increase in the resistance index (RI) even in the absence of overt clinical symptoms. These findings suggest that SH acts as an independent factor for endothelial dysfunction and requires early diagnostic monitoring.