Panic Disorder Workup

Updated: Mar 21, 2018
  • Author: Mohammed A Memon, MD; Chief Editor: Randon S Welton, MD  more...
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Approach Considerations

No invasive procedures are required to diagnose panic disorder, although they may be useful in eliminating other conditions in the differential diagnosis. As previously mentioned, history, collateral information, physical examination, and a mental status examination remain the diagnostic cornerstones for panic disorder.

Use electrocardiography (ECG) to assess for signs of ventricular preexcitation (short PR and delta wave), for short or long QT interval in patients with palpitations, and for ischemia, infarction, or pericarditis patterns in patients with chest pain. Outpatient Holter monitoring or transtelephonic event recording is rarely necessary but should be considered in patients with palpitations associated with syncope or near-syncope.

Patients who may be at risk for pulmonary embolism require appropriate testing (e.g., determination of D-dimer level, spiral CT scanning, ventilation-perfusion [V/Q] scanning, duplex Doppler/ultrasonography, or pulmonary angiography).


Diagnostic Studies

Laboratory studies that can exclude medical disorders other than panic disorder include the following:

  • Serum electrolytes to exclude hypokalemia and acidosis

  • Serum glucose to exclude hypoglycemia

  • Cardiac enzymes in patients suspected of acute coronary syndromes

  • Serum hemoglobin in patients with near-syncope

  • Thyroid-stimulating hormone (TSH) in patients suspected of hyperthyroidism

  • Urine toxicology screen for amphetamines, cannabis, cocaine, and phencyclidine in patients suspected of intoxication

  • D-dimer assay to exclude pulmonary embolism

Room air pulse oximetry values are usually within the reference range or at the upper limit of the reference range. End-tidal capnography values are typically less than 30 torr during hyperventilation.

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 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.

Human subjects with panic anxiety have elevated levels of orexin in the cerebrospinal fluid. Orexin, also known as hypocretin, is thought to play an important role in the pathogenesis of panic in rat models [31] ; it is also a potential gene of risk for panic disorder.


Radiologic Studies

No imaging study findings are currently specific for panic disorder, although they are performed to evaluate anatomic evidence of other diagnostic possibilities. Studies may include an electroencephalogram (EEG) to exclude partial complex seizures.

Investigational functional neuroimaging is not used in routine clinical practice for diagnosis or for monitoring treatment response. However, positron emission tomography (PET) scanning has demonstrated increased flow in the right parahippocampal region and reduced serotonin type 1A receptor binding in the anterior and posterior cingulate and raphe of patients with panic disorder. [15] Magnetic resonance imaging (MRI) has demonstrated smaller temporal lobe volume, despite normal hippocampal volume, in patients with panic disorder. [19]