Urinary composition during decongestive treatment in heart failure with reduced ejection fraction

Abstract

Background: The urinary composition, including sodium (Na(+)) and chloride (Cl(-)) concentrations, might provide useful information in addition to urine output during decongestive treatment in heart failure.

Methods and results: Consecutive patients with heart failure (n=61), ejection fraction ≤45%, worsening symptoms, and scheduled treatment with intravenous loop diuretics were included. Patients received protocol-driven therapy until complete decongestion, assessed clinically and by echocardiography. Three consecutive 24-hour urinary collections were performed. With 2 mg (1-4 mg), 1 mg (0-2 mg), and 1 mg (0-1 mg) bumetanide administered in bolus during consecutive 24-hour intervals, in addition to combinational diuretic therapy in ≈70% and both oral spironolactone and vasodilators in ≈90%, euvolemia was reached, often within 24 hours. Urine output was higher during the first when compared with the second or third 24-hour interval (2700 versus 1550 or 1375 mL, respectively; P<0.001), but this was no longer significant after correction for diuretic dose (P=0.263), indicating preserved diuretic efficiency during the study. In contrast, urinary Na(+) and Cl(-) excretion both decreased significantly, even after correction for diuretic dose (P=0.040 and 0.004, respectively), leading to decreasing urinary concentrations with progressive decongestion. After reaching euvolemia, lower urinary Na(+)/Cr and Cl(-)/Cr ratios were both associated with urine output ≤1500 mL (area under the curve, 0.830 and 0.826, respectively; P<0.001 for both), in contrast to plasma N-terminal pro-B-type natriuretic peptide levels that were not (area under the curve, 0.515; P=0.735) CONCLUSIONS: The urinary composition during progressive decongestion in heart failure with reduced ejection fraction is characterized by a drop in urinary Na(+) and Cl(-) concentrations. The urinary Na(+)/Cr or Cl(-)/Cr ratio might provide insightful information to titrate diuretic therapy.

Keywords: sodium; systolic heart failure; urea; urine.