Anxiety Disorders Workup

Updated: Mar 27, 2019
  • Author: Nita V Bhatt, FAPA, MD, MPH; Chief Editor: David Bienenfeld, MD  more...
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Approach Considerations

When the index of suspicion for anxiety being produced by a medical disorder is low (lack of physical findings, younger age, typical anxiety disorder presentation), initial laboratory studies might be limited to the following:

  • Complete blood cell count

  • Chemistry profile

  • Thyroid function tests

  • Urinalysis

  • Urine drug screen


Studies to Exclude Medical Disorders

For presentations with a higher index of suspicion for other medical causes of anxiety (ie, atypical anxiety disorder presentation, older age, specific physical examination abnormalities), more detailed evaluations may be indicated to identify or exclude underlying medical disorders.

Electroencephalography, lumbar puncture, and head/brain imaging

Rule out CNS disorder using electroencephalography (EEG), lumbar puncture, or brain computed tomography (CT) scan, as indicated by history and associated clinical findings. EEG may be used to exclude seizure disorder because these conditions may mimic anxiety.

Imaging studies are limited to presentations in which medical illness, such as a seizure disorder, is suspected. If headache is a prominent feature, an EEG or MRI could be considered along with neurologic consultation to rule out seizures or brain tumor. A head CT scan may be ordered for suspected intracranial abnormality, or an MRI scan for intracranial abnormality.

Functional MRI and PET scanning have shown increases in blood flow and metabolic activity in the orbitofrontal cortex, limbic structures, caudate, and thalamus, with a trend toward right-sided predominance, in patients with obsessive-compulsive disorder. In some studies, these areas of overactivity have been shown to normalize following successful treatment with either SSRIs or CBT. [41] These imaging modalities, however, are of value for research, and not indicated for normal workups.


Rule out cardiac disorders (eg, myocardial infarction) using electrocardiography (ECG) or treadmill ECG. ECG may be used to check for mitral valve prolapse or to exclude arrhythmia.

Tests for infection

Rule out infectious causes using rapid plasma reagent test, lumbar puncture (CNS infections), or HIV testing.

Arterial blood gas analysis

Arterial blood gas analysis is useful in confirming hyperventilation (respiratory alkalosis) and excluding hypoxemia or metabolic acidosis. The presence of hypoxemia with hypocapnia or a widened alveolar-arterial (A-a) gradient should increase the suspicion of pulmonary embolus.

Electrolyte analysis

Electrolyte analysis is unnecessary, although several abnormalities may be present in the setting of hyperventilation. Serum phosphorus and ionized calcium may be diminished in patients with hyperventilation and carpopedal spasm, Chvostek sign, or Trousseau sign. The serum calcium level may be within the reference range.

Chest radiography

Chest radiography is useful in excluding other causes of dyspnea with chest pain (eg, pulmonary embolism).

Thyroid function

Hyperthyroidism is one of the most common medical causes for anxiety related to a medical condition. Serum thyroid-stimulating hormone and T4 levels should be considered for excluding a primary thyroid abnormality.