Urinary biomarkers to predict severe fluid overload after cardiac surgery: a pilot study

Aim: To assess the predictive ability of urinary and plasma biomarkers and clinical routine parameters for subsequent severe fluid overload. Patients & methods: In a pilot study, we studied 100 adult patients after cardiac surgery. On intensive care unit admission, we measured biomarkers in urine (midkine, IL-6, neutrophil gelatinase-associated lipocalin [NGAL], hepcidin-25) and plasma (creatinine, urea, B-type natriuretic peptide, lactate, C-reactive protein, leukocytes, IL-6, NGAL, hepcidin-25) to predict postoperative severe fluid overload. Results: Urinary midkine, IL-6, NGAL and hepcidin-25 (all AUCs >= 0.79) predicted postoperative severe fluid overload (N = 5 patients). Urinary NGAL/hepcidin-25 ratio (AUC 0.867) predicted postoperative severe fluid overload after adjustment to EuroScore and need for norepinephrine on surgery day (odds ratio: 2.4). Conclusion: Urinary biomarkers on intensive care unit admission might be helpful to predict subsequent severe fluid overload after cardiac surgery. Tweetable abstract In a pilot study with 100 adult patients after cardiac surgery, we found that urinary biomarkers, but not blood biomarkers can help predict postoperative severe fluid overload after cardiac surgery. Lay abstract Aim: To assess whether proteins in the urine or blood or clinical routine laboratory parameters can predict severe body fluid overload after cardiac surgery. Patients & methods: In a pilot study, we studied 100 adult patients after cardiac surgery. After surgery, we measured proteins in the urine (midkine, IL-6, neutrophil gelatinase-associated lipocalin [NGAL], hepcidin-25) and blood (creatinine, urea, B-type natriuretic peptide, lactate, C-reactive protein, leukocytes, IL-6, NGAL, hepcidin-25) to predict postoperative severe fluid overload. Results: Urinary midkine, IL-6, NGAL and hepcidin-25 predicted postoperative severe fluid overload (N = 5 patients). Urinary NGAL/hepcidin-25 ratio predicted postoperative severe fluid overload after adjustment to important covariates. Conclusion: Urinary biomarkers might be helpful to predict subsequent severe fluid overload after cardiac surgery.