Non-furosemide-related renal calcifications in premature infants with bronchopulmonary dysplasia

Renal calcification is a known complication of long-term furosemide therapy in infants with bronchopulmonary dysplasia (BPD). In a prospective study the clinical course and long-term renal sequelae of renal calcifications of 19 consecutive premature neonates (birthweight < 1250 g) with bronchopulmonary dysplasia who did not receive furosemide were examined. Infants were divided into two different groups on the basis of ultrasound evidence of renal calcifications (RC group) or absence of renal calcifications (NRC group). Serial examinations, performed at the age of 1, 2, 3, 6, 9 and 12 months, showed that 12 infants at the mean age of 68.5 +/- 12.8 days of life had renal calcifications (63%), and 3 of them had nephrolithiasis; 8 had bilateral renal calcifications. Among the 9 survivors, 2 had chronic renal calcifications at the age of 9 months; however, all normalized at the age of 12 months. Twelve infants received hydrochlorothiazide and spironolactone (63%), 17 had prolonged courses of xanthines and dexamethasone (89.5%), while furosemide was not part of the routine pharmacological administration. Statistical analysis showed that birthweight, gestational age, Apgar score and length of parenteral nutrition were comparable in the RC and NRC group infants. Mean serum creatinine, creatinine clearance, fractional sodium excretion and urinary calcium excretion values during the 12-month study period were comparable in the RC and NRC groups. Mechanical ventilation and hospital stay length were instead associated with renal calcification occurrence. The strongest indicator of renal calcification risk for this high-risk population is the severity of the unresolved acute lung disease, where different facets of respiratory management, other than the addition of furosemide, represent sufficient stimuli and renal injury to potentiate stone formation.