Urinary aldosterone excretion and renal function in extremely-low-birth-weight infants following acute furosemide therapy

BACKGROUND: Increased activity of the renin-angiotensin-aldosterone system (RAAS) has been reported in the neonatal period. Until now, it has been demonstrated that the RAAS of healthy neonates responds to acute furosemide challenge while no data concerning the responsiveness of RAAS in extremely low birth weight (ELBW) infants are available. OBJECTIVE: To assess urinary aldosterone excretion (UAE) and renal function in ELBW infants who received diuretics for the purpose of reducing the incidence of chronic lung disease (CLD). METHODS: Infants with birth weights < or =1,000 g, at high risk to develop CLD, were studied in a prospective observational study. UAE and renal function were investigated before and after administration of furosemide given in a single dose of 2 mg/kg. RESULTS: UAE and renal function were evaluated in 20 ELBW infants. Diuretic administration resulted in a significant rise in UAE and urinary sodium, potassium and chloride excretion. No change occurred in creatinine clearance, while urine volume increased significantly. CONCLUSIONS: ELBW infants respond to acute furosemide challenge by increasing urine volume, urinary electrolytes and UAE.