Renal function and renal failure in the newborn.

Renal function in the newborn infant varies with conceptual age and should be evaluated in this context. Very preterm infants less than 34 weeks' conceptual age have reduced GFR and tubular immaturity in the handling of filtered solutes when compared to term infants. Premature infants between 34 and 37 weeks' conceptual age undergo rapid maturation of renal function similar to term infants, with establishment of glomerulotubular balance early in the postnatal period. ARF in neonates differs from that seen in older children and adults in that ischemic (e.g., hypoxic) insults and congenital malformations constitute the major pathophysiologic mechanisms responsible for clinically observed oliguria and azotemia. Principles of conservative management are similar to those used in older children except for the greatly increased insensible water loss requirements of the very preterm and premature infant. Technical advances have added peritoneal dialysis and CAVH to the therapeutic regimen for persistent ARF or life-threatening complications of reduced renal function.