eMedicine Specialties > Psychiatry > Emergency

Delirium: Differential Diagnoses & Workup

Author: Kannayiram Alagiakrishnan, MD, MBBS, Associate Professor, Department of Medicine, Division of Geriatric Medicine, University of Alberta
Coauthor(s): Patricia Blanchette, MD, Department Chair and Director, Geriatric Medicine Fellowship Program, Professor of Geriatric Medicine, Geriatric Medicine, John A Burns School of Medicine, University of Hawaii
Contributor Information and Disclosures

Updated: Aug 3, 2009

Differential Diagnoses

Depression

Other Problems to Be Considered

Dementia
AIDS-related complex
Psychosis

Dementia is one of the most important risk factors for delirium. It often coexists in patients who are hospitalized. Delirium may be a risk factor or marker for the development of dementia. The safest rule is to consider delirium when recent changes in an elderly patient's level of consciousness and cognition have occurred in an acute care setting.

Patients with hypoactive withdrawn delirium may be misdiagnosed as depressed. Depressed patients also may have cognitive symptoms, but the patient's level of consciousness is normal.

Delirium may have to be differentiated from psychosis because both have psychotic features. In delirium, the patient usually does not have a previous history of serious psychiatric illness. The onset of symptoms of delirium is acute or subacute, the hallucinations predominantly are visual and fluctuate, and the patient has impaired memory and orientation and clouding of consciousness.

Workup

Laboratory Studies

  • Complete blood cell count with differential - Helpful to diagnose infection and anemia
  • Electrolytes - To diagnose low or high levels
  • Glucose - To diagnose hypoglycemia, diabetic ketoacidosis, and hyperosmolar nonketotic states
  • Renal and liver function tests - To diagnose liver and renal failure
  • Thyroid function studies - To diagnose hypothyroidism
  • Urine analysis - Used to diagnose urinary tract infection
  • Urine and blood drug screen - Used to diagnose toxicological causes
  • Thiamine and vitamin B-12 levels - Used to detect deficiency states of these vitamins
  • Tests for bacteriological and viral etiologies - To diagnose infection
  • Sedimentation rate
  • Drug screen including alcohol level
  • HIV tests
  • Tests for other infectious causes if necessary or clinically indicated (These tests are not performed routinely, even though 30-40% of hospitalized patients with HIV infection develop delirium during hospitalization.21 )

Imaging Studies

  • Neuroimaging
    • Perform CT scan of the head.
    • Magnetic resonance imaging (MRI) of the head may be helpful in the diagnosis of stroke, hemorrhage, and structural lesions.
  • Electroencephalogram
    • In delirium, generally, slowing of the posterior dominant rhythm and increased generalized slow-wave activity are observed on electroencephalogram (EEG) recordings.
    • In delirium resulting from alcohol/sedative withdrawal, increased EEG fast-wave activity occurs.
    • In patients with hepatic encephalopathy, diffuse EEG slowing occurs.
    • The type of patterns observed includes triphasic waves in toxicity or metabolic derangement, continuous discharges in nonconvulsive status epilepticus, and localized delta activity in focal lesions.
  • Chest x-ray is used to diagnose pneumonia or congestive heart failure.

Other Tests

  • Lumbar puncture is indicated when CNS infection is suspected as a cause of delirium or when the source for the systemic infection cannot be determined.
  • Pulse oximetry is used to diagnose hypoxia as a cause of delirium.
  • Electrocardiogram is used to diagnose ischemic and arrhythmic causes.

More on Delirium

Overview: Delirium
Differential Diagnoses & Workup: Delirium
Treatment & Medication: Delirium
Follow-up: Delirium
References
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References

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Further Reading

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Keywords

acute confusional state, acute cognitive dysfunction, toxic metabolic encephalopathy, hyperactive delirium, hypoactive delirium, mixed delirium

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Contributor Information and Disclosures

Author

Kannayiram Alagiakrishnan, MD, MBBS, Associate Professor, Department of Medicine, Division of Geriatric Medicine, University of Alberta
Kannayiram Alagiakrishnan, MD, MBBS is a member of the following medical societies: American College of Physicians, American Geriatrics Society, and American Medical Association
Disclosure: Nothing to disclose.

Coauthor(s)

Patricia Blanchette, MD, Department Chair and Director, Geriatric Medicine Fellowship Program, Professor of Geriatric Medicine, Geriatric Medicine, John A Burns School of Medicine, University of Hawaii
Patricia Blanchette, MD is a member of the following medical societies: American College of Physicians, American Geriatrics Society, American Medical Association, American Medical Directors Association, Gerontological Society of America, and Hawaii Medical Association
Disclosure: Nothing to disclose.

Medical Editor

Mohammed A Memon, MD, Medical Director of Geriatric Psychiatry, Department of Psychiatry, Spartanburg Regional Hospital System
Mohammed A Memon, MD is a member of the following medical societies: American Association for Geriatric Psychiatry, American Medical Association, and American Psychiatric Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Iqbal Ahmed, MBBS, Professor, Department of Psychiatry, John A Burns School of Medicine, University of Hawaii
Iqbal Ahmed, MBBS is a member of the following medical societies: Academy of Psychosomatic Medicine, American Association for Geriatric Psychiatry, American Neuropsychiatric Association, and American Psychiatric Association
Disclosure: Nothing to disclose.

CME Editor

Harold H Harsch, MD, Program Director of Geropsychiatry, Department of Geriatrics/Gerontology, Associate Professor, Department of Psychiatry and Department of Medicine, Froedtert Hospital, Medical College of Wisconsin
Harold H Harsch, MD is a member of the following medical societies: American Psychiatric Association
Disclosure: lilly Honoraria Speaking and teaching; Forest Labs Honoraria Speaking and teaching; AstraZeneca Honoraria Speaking and teaching; Pfizer Grant/research funds Speaking and teaching; Northstar Grant/research funds Research; Novartis Grant/research funds research; Pfizer  Speaking and teaching; Sanofi-avetis Grant/research funds research; Otsuke Grant/research funds reseach; GlaxoSmithKline Grant/research funds research

Chief Editor

Stephen Soreff, MD, President of Education Initiatives, Nottingham, NH; Faculty, Metropolitan College of Boston University, Boston, MA
Stephen Soreff, MD is a member of the following medical societies: American College of Mental Health Administration and American Psychosomatic Society
Disclosure: Nothing to disclose.

 
 
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