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Mr. G is a 56-year-old African American man with diabetes, chronic hepatitis B, CAD status post MI 2 months ago, hypertension, and a history of stroke 1 year ago. He is taking many medications, including Humulin 70/30 20 units twice daily, metoprolol, aspirin, atorvastatin, lisinopril, furosemide, and ribavirin. Despite all of these problems, he has been slowly improving and reported at his last visit 3 weeks ago that he had recently given up his walker for a cane. Today you are paged by his sister, who reports that Mr. G is very weak and cannot get up; his home glucose monitor reading is “critical high.” Mr. G’s voice is barely recognizable over the phone, and he is unable to respond to your questions. You advise his sister to call 911.

image At this point, what is the leading hypothesis, what are the active alternatives, and is there a must not miss diagnosis? Given this differential diagnosis, what tests should be ordered?


The differential diagnosis at this point is very broad and difficult to organize. It is helpful to recognize that Mr. G appears to be suffering from the syndrome of delirium and to use the framework for delirium to organize your thinking (see Constructing a Differential Diagnosis). It is also reasonable to consider Mr. G’s underlying chronic medical problems as important clinical clues and initially focus on the serious complications of these conditions; in other words, initially focus on diseases for which he has a high pretest probability:

  1. Diabetes: DKA, HHS, infection with or without sepsis.

  2. CAD: recurrent MI, possibly with heart failure or cardiogenic shock

  3. Cerebrovascular disease: recurrent stroke

  4. Chronic hepatitis B: hepatic encephalopathy

Table 12-11 lists the differential diagnosis.

Table 12-11.Diagnostic hypotheses for Mr. G.


Mr. G could have any, or a combination, of these conditions. His critical high blood sugar makes a complication of diabetes the leading hypothesis; all of the other diagnoses are “must not miss” hypotheses.

When Mr. G arrives in the emergency department, he is barely responsive but able to move all 4 extremities. His BP is 85/50 mm Hg; pulse, 120 bpm; RR, 24 breaths per minute; temperature, 37.2°C. His lungs are clear, and cardiac exam shows an S4 with no S3 or murmurs. His abdomen is ...

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