Severe non-hepatic hyperammonaemic encephalopathy in an immunocompromised adolescent with enterocolitis

Non-hepatic causes of hyperammonaemia are uncommon relative to hepatic aetiologies. An adolescent female was admitted to the hospital with a diagnosis of very severe aplastic anaemia. During her treatment with immunosuppressive therapy, she developed neutropenic enterocolitis, pseudomonal bacteraemia and hyperammonaemia. A combination of intermittent haemodialysis and high-volume continuous veno-venous haemodiafiltration (CVVHDF) was required to manage the hyperammonaemia. Despite a thorough investigation, there were no hepatic, metabolic or genetic aetiologies identified that explained the hyperammonaemia. The hyperammonaemia resolved only after the surgical resection of her inflamed colon, following which she was successfully weaned off from the renal support. This is a novel case report of hyperammonaemia of non-hepatic origin secondary to widespread inflammation of the colon requiring surgical resection in an immunocompromised patient. This case also highlights the role of high-volume CVVHDF in augmenting haemodialysis in the management of severe refractory hyperammonaemia.