Hyperammonemia in the Pediatric Emergency Care Setting

Hyperammonemia is encountered frequently in acutely ill children presenting for emergency care with altered levels of consciousness (ALOC). Ammonia production, metabolism, and excretion are affected by different variables. Hyperammonemia may be a transient state or may signify more grave etiologies as inborn errors of metabolism. Levels of ammonia are also affected by proper sampling technique, transport, and analysis. Objectives: To determine the level of ammonia in acutely ill children with ALOC, identify causes of hyperammonemia, and correlate levels with illness severity and morbidity. Design: Observational study. Setting: Emergency department at Cairo University Specialized Paediatric Hospital. Methods: Fifty cases of acutely ill pediatric patients with ALOC who presented to the emergency department were included in the study from 2008 through 2009. Emergency department patients (n = 20) with known diseases that may induce hyperammonemia were excluded. Patients were subjected to detailed history taking with emphasis on factors affecting ammonia levels and thorough clinical examination. A cohort group of age-and sex-matched children acted as a control group. Results: The measured blood ammonia level ranged between 13 and 265 Kmol/L, with a mean level of 95 Kmol/L. Sixty percent of the children with ALOC had ammonia levels of greater than 75 Kmol/L, with levels greater than 200 Kmol/L seen in 6% of the studied sample. The study demonstrated a highly significant statistical difference between children with ALOC and control groups. There was no correlation between blood ammonia level and age. Correlations of ammonia levels were also conducted in comparison with etiological diagnoses and laboratory parameters with no statistical significance. There was no statistical significance between ammonia level and duration of illness, Sequential Organ Failure Assessment score, or Glasgow Coma Scale score/Morray Scale score. Conclusions: Clinicians should consider testing children with ALOC for hyperammonemia, provided that a clear understanding of its metabolism and factors controlling it are understood. Proper sampling must be ensured. Mild elevations of ammonia levels are fairly common, but exceedingly high levels should raise concern and may require further evaluation.