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 (D₇). Blood and urine samples were taken daily and sodium and water balance strictly calculated resulting in a total cumulative assessment of δNa⁺ and δH₂O. 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 D₂, D₅ and D₇. Blood volumes were measured with ⁵¹Cr fixed on red blood cells at D₂ and D₇. Results: The δNa⁺ or δH₂O were increased in all patients but never related to blood volumes at D₂ nor D₇. 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 δNa⁺ or δH₂O. 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 δNa⁺ or δH₂O and predicts sodium and extracellular fluid overload. Trial registration: ClinicalTrials.gov: NCT01858675in May 13, 2013.