Urinary aldosterone excretion and electrolytic balance in response to chronic diuretic therapy in very low birth weight infants.

Background. It has been reported that the renin-angiotensin-aldosterone system (RAAS) of healthy newborn infants and preterm infants responds to acute furosemide challenge. Objective. To assess urinary aldosterone excretion (UAE) and electrolytic balance (EB) in very low-birth weight (VLBW) infants who received chronic therapy with furosemide and to compare them with those of infants who did not receive diuretic therapy. Methods. Infants with birth weight <1500 grams were considered eligible for this prospective observational study. On the 10th day of life, infants enrolled were divided in two groups on the basis of our predictive score for chronic lung disease (CLD): group 1, with positive score, received furosemide and group 2, with negative score, did not receive diuretic therapy. Urinary aldosterone and electrolytes excretion, electrolytes intakes and clearance of creatinine were investigated before the beginning of the treatment and then weekly until discharge in both groups, and results were compared. Results. Thirty infants were studied: fifteen received long-term furosemide and fifteen did not. UAE progressively increased in infants who received furosemide whereas remained unchanged in infants who did not receive treatment. UAE was greater in group 1 than in group 2 after three weeks of diuretic treatment, reaching statistical significance after four weeks of treatment. Conclusions. In VLBW infants chronic therapy with furosemide leads to a progressive increase in UAE, that may potentially limit the diuretic effect of long-term use of furosemide in the management of CLD.