Association Between Continuous Kidney Replacement Therapy Clearance and Outcome in Pediatric Patients With Hyperammonemia Not Due to Inborn Error of Metabolism

OBJECTIVES: To describe a single-center experience of pediatric patients with hyperammonemia not due to inborn errors of metabolism and determine the association between use of continuous kidney replacement therapy (CKRT) treatment and outcomes. DESIGN: Retrospective cohort study. SETTING: Tertiary-care children's hospital. PATIENTS: All children less than 21 years old admitted to the hospital with hyperammonemia defined as an elevated ammonia levels (>100 µmol/L) not due to inborn error of metabolism. INTERVENTIONS: None. MEASURES AND MAIN RESULTS: Of 135 children with hyperammonemia, the most common reason for admission was infection in 57 of 135 (42%), congenital heart disease in 20 of 135 (14%), and bone marrow transplantation in 10 of 135 (7%). The overall mortality was 61% (82 of 135), which increased with degree of hyperammonemia (17 of 23 [74%] in those with ammonia >250 µmol/L). After multivariable regression, hyperammonemia severity was not associated with mortality (aOR, 1.4; 95% CI, 0.92-2.1; p = 0.11). Of the 43 patients (32%) receiving CKRT, 21 were prescribed standard clearance and 22 high clearance. The most common indications for CKRT were fluid overload in 17 of 43 (42%) and acute kidney injury or uremia in 16 of 43 (37%). Mean CKRT duration was 13 days. There was no difference between standard and high clearance groups in risk of death (76% vs 86%; p = 0.39), cerebral edema on CT scan (19% vs 27%; p = 0.52), nor decrease in ammonia levels after 24 or 48 hours of CKRT ( p = 0.20, p = 0.94). Among those receiving CKRT, we failed to find an association between high clearance and decreased risk of death in multivariable analysis (aOR, 1.2; 95% CI, 0.64-2.3; p = 0.55). CONCLUSIONS: In our single-center retrospective study, we failed to find an association between clearance on CKRT and improved survival nor decreased cerebral edema on head imaging. In fact, we failed to find an association between ammonia level and mortality, after controlling for illness severity.