Answer targeted questions : PSY-Q

Question : 1 / 258

A 82 year old man with a history of Bipolar Disorder is brought to the emergency department for strange behavior. He lives in an assisted living facility and screamed at a nursing assistant who came in his room to wake him up, saying “They’re coming! They’re coming to take all of us!” He was able to converse with her managing nurse 20 minutes later, but an hour later left his room without having dressed, and shouted at other residents. In the emergency department, he appears somnolent, then confused, and unable to pay attention to your questions. His medications are atorvastatin, daily aspirin, and lithium therapy, which he has taken for 40 years. Mental status is significant for an agitated, confused appearing man who is not oriented to person, place, time, or situation. Temperature is 98.3, heart rate is 97, blood pressure is 98/74, and respiratory rate is 12. Physical exam is significant for dry mucus membranes and abnormal skin turgor. Neurological exam is limited due to patient cooperation but is within normal limits with the exception of mental status. Which of the following diagnostic studies is most likely to reveal the cause for his presentation?

CT head
Psychiatric review of systems
CBC
BMP

The answer is D, basic metabolic panel. This patient’s presentation appears to be delirium and he has signs of hypovolemia on physical exam (elevated heart rate, lower blood pressure, dry mucus membranes, skin turgor). Many patients on long term lithium therapy develop nephrogenic diabetes insipidus, causing frequent, diluted urination. While most patients are able maintain euvolemia without any electrolyte disturbances by drinking fluids, elderly patients on chronic lithium therapy who require higher levels of care are at risk of hypernatremia. Delirium has a long list of possible precipitating factors, and electrolyte disturbances are among them. This patient likely became delirious due to urinating frequently, not drinking enough water, and finally becoming dehydrated and hypernatremic. After treating the underlying disorder, haloperidol is often used in these cases to treat agitation. Delirium is an extremely common medical emergency frequently seen in older patients. It is a neuropsychiatric disorder characterized by an acute development of disturbance of consciousness and fluctuating changes in cognition, attention, and perceptual disturbance. About 50% of cases are associated with those who have a brain disease (dementia, history of stroke, or Parkinson’s), and can be precipitated by many things: infection (UTI is a common cause), polypharmacy, electrolyte derangements, intoxication, withdrawal, pain, and more. Interestingly, other factors such as immobility, poor vision, and even just having a urinary catheter have been highly associated with delirium. A), CT head is incorrect because given a normal neuro exam, it is less likely a stroke. Stroke can precipitate a delirium and would certainly be included in the differential in this case. B), Further psychiatric ROS might be useful; however, the patient is unable to give a coherent history. Mania could explain his altered mental status-- however, the picture in the vignette is of fluctuations of cognition, attention, and perception that is better explained by delirium. C, CBC would be useful if his delirium were caused by infection (elevated white blood cells) and this vignette does not rule out a delirium associated with a UTI. It is just less likely given his history of lithium and apparent dehydration. A basic workup for delirium might include review of medications, CBC, CMP, urinalysis, and CT head to look for one of these potential causes.

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