Carbamoyl phosphate synthetase 1 (CPS1) deficiency is an autosomal recessive
urea cycle disorder with varying presentations. Patients with a neonatal-onset phenotype are initially healthy but develop severe
hyperammonemia days after birth and often have poor or lethal outcomes, while patients who present later in life may exhibit less severe clinical manifestations. CPS1 deficiency is rarely found on newborn screening because most states do not screen for this disease due to the technical difficulties. We report a case of an 11-year-old, previously healthy girl who presented with
hyperammonemia and acute
psychosis after eating large amounts of meat at summer camp. A diagnosis of
carbamoyl phosphate synthetase type 1 deficiency was suspected by biochemical profiles and confirmed by molecular analysis. Subsequent follow up lab results revealed
ammonia to be only 25-39 μmol/L shortly after
glutamine reached levels as high as 770-1432 μmol/L with concurrent
alanine elevations, highlighting the compensating mechanisms of the human body. Her initial hospital course also demonstrated the importance of
continuous renal replacement therapy (CRRT) in avoiding rebound
hyperammonemia and high
glutamine and the benefits of intracranial pressure (ICP) monitoring, providing 3% hypertonic saline and temperature control to avoid
fever in treating
cerebral edema.
Carglumic acid was not considered helpful in this case, with BUN levels ranging between 2 and 4 mg/dL after administration.