How can I differentiate between hepatic encephalopathy and other causes of altered mental status in a patient?

To differentiate hepatic encephalopathy (HE) from other causes of altered mental status, focus on clinical context, characteristic features, and targeted investigations.

HE typically occurs in patients with known or suspected liver disease, especially cirrhosis or acute liver failure, and presents with a spectrum of neuropsychiatric symptoms ranging from subtle cognitive impairment to coma NICE CG100. The presence of precipitating factors such as gastrointestinal bleeding, infection, electrolyte disturbances, or medication changes supports HE diagnosis NICE CG100.

Clinically, HE often manifests with asterixis (flapping tremor), disorientation, altered sleep patterns, and personality changes, which are less common in other causes of encephalopathy NICE CG100. In contrast, other causes of altered mental status (e.g., metabolic, infectious, structural brain lesions) may lack these specific signs and have different clinical contexts NICE NG127.

Laboratory investigations are crucial: elevated serum ammonia levels support HE but are not diagnostic alone, as ammonia can be elevated in other conditions Sargent 2007. Liver function tests and coagulation profiles indicating hepatic dysfunction strengthen the suspicion of HE NICE CG100. Neuroimaging (CT or MRI) is important to exclude structural brain causes of altered mental status NICE NG127.

Response to empirical treatment with lactulose or rifaximin can also help differentiate HE, as improvement in mental status following ammonia-lowering therapy is characteristic Sargent 2007.

In summary, differentiation relies on identifying underlying liver disease, typical clinical features such as asterixis, exclusion of other causes via imaging and labs, and response to specific HE treatments NICE CG100,NICE NG127 Sargent 2007.