Diuretic response and effects of diuretic omission in ambulatory heart failure patients on chronic low‐dose loop diuretic therapy

AIMS: To study loop diuretic response and effect of loop diuretic omission in ambulatory heart failure (HF) patients on chronic low-dose loop diuretics. METHODS AND RESULTS: Urine collections were performed on two consecutive days in 40 ambulatory HF patients with 40-80 mg furosemide (day 1 with loop diuretic; day 2 without loop diuretic). Three phases were collected each day: (i) first 6 h; (ii) rest of the day; and (iii) night. On the day of loop diuretic intake, the total natriuresis was 125.9 (86.9-155.0) mmol/24 h and urine output was 1650 (1380-2025) mL/24 h. There was a clear loop diuretic response with a natriuresis of 9.4 (6.7-15.9) mmol/h and a urine output of 117 (83-167) mL/h during the first 6 h, followed by a significant drop in natriuresis and urine output during the rest of the day [2.6 (1.8-4.8) mmol/h and 55 (33-71) mL/h] and night [2.2 (1.6-3.5) mmol/h and 44 (34-73) mL/h]. On day 2, after loop diuretic omission, the natriuresis and urine output remained similarly low the entire day, resulting in a 50% reduction in natriuresis [55.1 (33.5-77.7) mmol/24 h; P < 0.001] and a 31% reduction in urine output [1035 (875-1425) mL/24 h; P < 0.001] compared with the day of loop diuretic intake. CONCLUSION: Patients with HF on chronic loop diuretic treatment still have a clear diuretic response phase, while loop diuretic omission leads to a significant drop in natriuresis and urine output, arguing against routine cessation of low-dose loop diuretics.