What labs should be checked in patients presenting with severe anxiety and panic?

Laboratory Tests for Patients with Severe Anxiety and Panic

Thyroid function tests (TSH and free T4) should be the primary laboratory tests ordered for all patients presenting with severe anxiety and panic attacks, with additional testing guided by clinical presentation rather than routine extensive screening. 1

Core Laboratory Tests

• Thyroid Function Tests:

  • TSH and free T4 - Essential for all patients with anxiety/panic 1
  • Rationale: Significant comorbidity exists between anxiety disorders and thyroid dysfunction 2, 1
  • Female patients with panic disorder may have higher prevalence of thyroid dysfunction 1

• Basic Metabolic Panel:

  • Complete metabolic panel (CMP) - Assess electrolytes, glucose, kidney and liver function 1
  • CBC - Screen for anemia, infection, or other hematologic abnormalities 1
  • Lipid profile - For baseline cardiovascular assessment 1

Additional Targeted Testing

Based on specific clinical presentations, consider:

• For cardiovascular symptoms: ECG 1
• For episodic hypertension or flushing:
  • Plasma-free metanephrine or urinary vanillylmandelic acid (pheochromocytoma) 1
  • Serum serotonin or urinary 5-hydroxyindoleacetic acid (carcinoid syndrome) 1
• For suspected hypoglycemia: Glucose testing 1

Clinical Decision Algorithm

1. For ALL patients with anxiety/panic: Order TSH and free T4
2. For patients with specific symptoms:
   • Cardiovascular symptoms → Add ECG
   • Episodic hypertension/flushing → Add pheochromocytoma screening
   • Hypoglycemia symptoms → Add glucose testing
   • Constitutional symptoms → Add CBC
   • Electrolyte disturbances suspected → Add CMP

Important Considerations

• Avoid excessive testing: The American College of Emergency Physicians warns against routine extensive laboratory testing, as false positive results are 8 times more frequent than true positives 1

• Medical mimics to consider:

  • Hyperthyroidism
  • Hypoglycemia
  • Cardiac arrhythmias
  • Pheochromocytoma
  • Seizure disorders
  • Asthma
  • Lead intoxication 1, 3

• Screening tools to incorporate:

  • GAD-7 (scores ≥10 suggest moderate anxiety; ≥15 suggest severe anxiety) 1
  • GAD-2 for rapid initial screening (score ≥3 is positive) 1
  • Panic Disorder Severity Scale (PDSS) for panic disorder screening 3

Thyroid-Anxiety Relationship

• Studies show correlations between thyroid hormone levels and anxiety severity in non-medicated patients 4
• Higher TSH levels correlate with more severe panic attacks 4
• Severity of anxiety correlates negatively with free T4 levels 4
• The optimal target TSH range for most patients with thyroid disorders is in the mid-normal range (1-3 mU/L) to avoid exacerbation of anxiety symptoms 1

Remember that while laboratory testing is important to rule out medical causes of anxiety, the diagnosis of anxiety disorders remains primarily clinical, requiring assessment of symptoms over time and consideration of other psychiatric comorbidities.