Metabolic-genetic work up revealed a metabolic pattern-- elevated glutamine and urine orotic acid with low total and free citrulline level-- consistent with proximal urea cycle defect likely OTC- Ornithine transcarboxylase deficiency or CPS1- Carbamoyl phosphate synthetase 1 deficiency.
The next generation sequencing test was negative for any genetic cause (Urea cycle enzymes or transporters) of hyperammonemia. Thus, chronic pancreatitis leading to exocrine pancreatic insufficiency, protein and micronutrient malnutrition was considered to be the etiology of secondary/acquired urea cycle dysfunction leading to hyperammonemia. IV Scavenger therapy with L Carnitine, Arginine and ammonul- combination of sodium benzoate and sodium phenylacetate contributed to resolution of hyperammonemia, encephalopathy and MRI changes.