Nonoliguric acute renal failure in the newborn: a prospective evaluation of diagnostic indexes

Fifteen newborn babies with azotemia without oliguria were studied. Group A infants had increased BUN levels and decreased creatinine clearance (Ccr) for gestational and postnatal age, and were compared with group B infants, who had increased BUN levels and normal Ccr. The Ccr was 0.35 mL/min in group A and 0.76 mL/min in group B. Urine volume during the same period was 2.45 mL/kg/hr in group A and 4.66 mL/kg/hr in group B. No significant differences in fractional sodium excretion; urine to plasma ratios of creatinine, osmolality, and sodium; and renal failure index were present between the two groups. The results suggest that nonoliguric acute renal failure is a diagnostic entity in the newborn. The Ccr is the most useful indicator for defining renal function in the presence of azotemia and normal urine volume.