Background

Hyperammonemia is a rare but serious cause of encephalopathy, commonly associated with hepatic dysfunction. However, non-hepatic hyperammonemia (NHHA) can arise due to impaired gastrointestinal transit, urease-producing organisms, and metabolic disorders. We present a case of NHHA following coronary artery bypass grafting (CABG).

Case presentation

A 56-year-old male with chronic alcohol use developed post-operative ileus and altered mental status on post-operative day 5 after an uncomplicated CABG. Despite normal liver function, ammonia levels peaked at 256 µmol/L. Given ileus, conventional therapy was deferred and continuous renal replacement therapy (CRRT) was initiated, resolving encephalopathy.

Conclusions

NHHA should be considered in post-cardiac surgery patients presenting with altered mental status. Early recognition and CRRT intervention are crucial to prevent neurological deterioration.