Sepsis is a life-threatening organ dysfunction caused by the dysregulation of the host's response to an infection, where the dominant mechanism is tissue hypoperfusion. Currently, the marker used to define tissue disorders is lactate levels, which may be elevated in other disease states as well. Renin is an essential hormone for the proper functioning of the renin-angiotensin-aldosterone (RASS) system. It is secreted in the glomerular apparatus in response to hypoperfusion. This study aimed to assess the usefulness of renin as a marker of tissue hypoperfusion in patients with sepsis and septic shock. A final group of 48 patients treated for sepsis and septic shock in the intensive care unit was included. Blood samples for renin quantification were collected in the morning as a part of routine blood analysis on the first, third, and fifth days. Sepsis was diagnosed in 19 patients (39.6%), and septic shock was diagnosed in 29 patients (60.4%). There was no significant difference in renin concentration between patients who received and did not receive continuous renal replacement therapy (CRRT) on any study day. Therefore, all samples were analyzed together in subsequent analyses. There was a significant difference in renin concentration between sepsis survivors and non-survivors on the third (31.5 and 119.9 pg/mL, respectively) and fifth (18.2 and 106.7 pg/mL, respectively) days. As a survival marker, renin was characterized by 69% and 71% overall accuracy if determined on the third and fifth days, respectively. There was a significant difference in renin concentration between sepsis and septic shock patients on the first (45.8 and 103.4 pg/mL, respectively) and third (24.7 and 102.1 pg/mL, respectively) days. At an optimal cut-off of 87 pg/mL, renin had very good specificity and a positive likelihood ratio. Renin was a strong predictor of mortality in patients with sepsis and septic shock. Further, the level of renin in patients with septic shock was significantly higher than in patients with sepsis. In combination with the assessment of lactate concentration, renin seems to be the optimal parameter for monitoring tissue hypoperfusion and could be helpful for septic shock diagnosis, as well as for identifying candidate patients for CRRT.
Keywords: lactate concentration; mortality rate; renin-angiotensin-aldosterone system; sepsis; septic shock; survival marker.