Mid-regional pro-adrenomedullin (MR-proADM), a marker of positive fluid balance in critically ill patients: results of the ENVOL study

Background: The optimal control of blood volume without fluid overload is a main challenge in the daily care of intensive care unit (ICU) patients. Accordingly this study focused on the identification of biomarkers to help characterize fluid overload status. Methods: Sixty-seven patients were studied from ICU admission to day 7 (D-7). Blood and urine samples were taken daily and sodium and water balance strictly calculated resulting in a total cumulative assessment of Delta Na+ and Delta H2O. Furthermore, plasmatic biomarkers (cortisol, epinephrine, norepinephrine, renin, angiotensin II, aldosterone, pro-endothelin, copeptine, atrial natriuretic peptide, erythropoietin, mid-regional pro-adrenomedullin (MR-proADM)) and Sequential Organ Failure Assessment (SOFA) scores were measured at D-2, D-5 and D-7. Blood volumes were measured with Cr-51 fixed on red blood cells at D-2 and D-7. Results: The Delta Na+ or Delta H2O were increased in all patients but never related to blood volumes at D-2 nor D-7. Total blood volumes were at normal values with constantly low red blood cell volumes and normal or decreased plasmatic volume. Weight, plasmatic proteins, and hemoglobin were weakly related to Delta Na+ or Delta H2O. Amongst all tested biomarkers, only MR-proADM was related to sodium and fluid overload. This biomarker was also a predictor of SOFA scores. Conclusions: Plasmatic concentration in MR-proADM seems to be a good surrogate for evaluation of Delta Na+ or Delta H2O and predicts sodium and extracellular fluid overload.