Alteration of mental status secondary to medical illness may occasionally b
e incorrectly attributed to a psychiatric problem. The cases of 64 patients
with unrecognized medical emergencies inappropriately admit ted to psychia
tric units from emergency departments were reviewed to determine the cause
of the misdiagnoses. Medical diagnoses most often missed included severe in
toxication with alcohol or other illicit sub stance (34.4%), drug or alcoho
l withdrawal or delirium tremens (12.5%), and prescription drug overdose (1
2.5%). In none of the cases (0%) was an appropriate mental status examinati
on performed. Other common causes of misdiagnosis included inadequate physi
cal examination (43.8%), failure to obtain indicated laboratory studies (34
.4%), and failure to obtain available history (34.4%). A systematic approac
h is required for patients with altered mental status, including those with
psychiatric presentations.