Serum ammonia level for the evaluation of hepatic encephalopathy.
JAMA. 2014 Aug 13;312(6):643–4. PMID25117134

Classic teaching tell us that the diagnosis of hepatic encephalopathy (HE) is based on serum ammonia levels, but not really.

Ammonia levels can be very important in assessment and prognosis for acute liver failure, but they can not be used to rule out or rule in HE.

Surprisingly the diagnosis of HE is clinical, based on history and physical exam.

Back to Basics of History and Physical Examination!

G Mohan.