Delirium Workup

Updated: Apr 25, 2019
  • Author: Kannayiram Alagiakrishnan, MD, MBBS, MPH, MHA; Chief Editor: Glen L Xiong, MD  more...
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Laboratory Studies

Laboratory tests that may be helpful for diagnosis include the following:

  • 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 including syphilis

  • 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. [32] )

  • Serum marker for delirium: The calcium-binding protein S-100 B could be a serum marker of delirium. Higher levels are seen in patients with delirium when compared to patients without delirium. [33]


Imaging Studies

See the list below:

  • 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 radiograph 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.