Diverting the Diagnosis: A Case Report of Hemodialysis Masking the Etiology of Hyperammonemia

Abstract

Rationale: Hyperammonemia in patients receiving hemodialysis is uncommon but poses a significant clinical challenge due to the effective clearance of ammonia by dialysis, which can obscure the underlying cause. Recognizing atypical etiologies is crucial for appropriate management. Presenting Concerns of the Patient: A 59-year-old man being treated with hemodialysis presented with altered level of consciousness and recurrent hyperammonemia. Despite previous episodes of hyperammonemia, the etiology of his intermittently elevated ammonia remained unclear and was initially attributed to his kidney failure. Diagnoses: Initial assessments, including liver function tests, abdominal ultrasound, medication review, and genetic screening for urea cycle disorders, were unremarkable. Upon recurrence of symptoms with hyperammonemia, a computed tomography scan was performed which revealed a large portosystemic shunt between the splenic vein and right common iliac vein. Interventions: The patient underwent embolization of the identified portosystemic shunt. Outcomes: Following embolization of the shunt, the patient’s hyperammonemia and encephalopathy resolved, with no further recurrences. Novel Findings: This case illustrates the challenges of determining the etiology of hyperammonemia in patients treated with hemodialysis due to the dialysis clearance of ammonia. Portosystemic shunts cause hyperammonemia by bypassing the liver’s ammonia-detoxification pathways, and their effects may be paradoxically exacerbated immediately after dialysis due to dialysis-related hemodynamic changes. We emphasize the importance of investigating hyperammonemia as a cause of altered level of consciousness among patients being treated with hemodialysis and considering anatomical shunting in the differential diagnosis.