Introduction Carbamyl phosphate synthetase (CPS) deficiency is a urea cycle defect leads to elevated blood ammonia levels CPS deficiency is a rare autosomal recessive disease Presentation Presents with Anorexia Irritability Heavy or rapid breathing Lethargy Vomiting Physical Exam shows Poor coordination Hypotonia or hypertonia Ataxia Tremor Evaluation The sole laboratory criterion for early diagnosis is a blood ammonia level ammonia levels usually are 10-20 times higher than reference range Treatment Reduce protein intake For extremely high blood ammonia hemodialysis is indicated Prognosis, Prevention, and Complications CPS deficiency is generally catastrophic in nature and leads to rapid demise without rapid recognition and treatment