Association of Relaxin-1 Levels with Mortality in Sepsis and Septic Shock

Background/Objectives: Hemodynamic disturbances in sepsis and septic shock arise from the vasoactive effects of inflammatory mediators involved in the immune response. Relaxin-1 is a pleiotropic hormone associated with inflammation, angiogenesis, tissue repair, and vasodilation. This study aimed to investigate the changes in relaxin-1 levels in septic shock and to evaluate their association with mortality. Methods: This prospective observational study was conducted in a Level II intensive care unit. Demographic characteristics, vital signs, APACHE II and SOFA scores, comorbidities, and routine laboratory parameters were recorded at admission and at 48 h. Serum relaxin-1 levels were measured at both time points and analyzed in relation to survival status. Binary logistic regression was additionally performed to evaluate variables associated with mortality in a multivariable framework. Results: A total of 48 patients with sepsis and septic shock were included (54.2% female; mean age 73.4 ± 14.7 years). Overall mortality was 33.3%. Relaxin-1 levels significantly increased from baseline (11.25 ± 4.85 pg/mL) to 48 h (12.64 ± 4.81 pg/mL) (p = 0.047). Baseline relaxin-1 levels were significantly higher in non-survivors compared to survivors (14.62 ± 4.47 pg/mL vs. 11.65 ± 4.73 pg/mL, p = 0.043). Conclusions: Elevated Relaxin-1 levels were associated with mortality in patients with sepsis and septic shock. The observed increase in Relaxin-1 during early follow-up suggests a potential link with the underlying pathophysiological processes. Although Relaxin-1 was associated with mortality, its independent prognostic value could not be established in multivariable analysis due to the limited sample size. Larger, adequately powered multicenter studies are required to confirm these findings.