High-dose continuous renal replacement therapy for neonatal hyperammonemia

Infants with hyperammonemia can present with nonspecific findings so ordering an ammonia level requires a high index of suspicion. Renal replacement therapy (RRT) should be considered for ammonia concentrations of > 400 mu mol/L since medical therapy will not rapidly clear ammonia. However, the optimal RRT prescription for neonatal hyperammonemia remains unknown. Hemodialysis and continuous renal replacement therapy (CRRT) are both effective, with differing risks and benefits. We present the cases of two neonates with hyperammonemia who were later diagnosed with ornithine transcarbamylase deficiency and received high-dose CRRT. Using dialysis/replacement flow rates of 8,000 mL/h/1.73 m(2) (1,000 mL/h or fourfold higher than the typical rate used for acute kidney injury) the ammonia decreased to < 400 mu mol/L within 3 h of initiating CRRT and to < 100 mu mol/L within 10 h. We propose a CRRT treatment algorithm to rapidly decrease the ammonia level using collaboration between the emergency department and departments of genetics, critical care, surgery/interventional radiology, and nephrology.