What laboratory tests should be ordered for a patient with chronic anxiety?

Laboratory Tests for Patients with Chronic Anxiety

For patients with chronic anxiety, laboratory testing should be focused on ruling out medical conditions that can mimic or exacerbate anxiety symptoms, with thyroid function tests being the most important screening test to perform. 1

Core Laboratory Panel for Anxiety Evaluation

Essential Tests

• Thyroid Function Tests (TSH, free T4)

  • Thyroid dysfunction and anxiety disorders have significant comorbidity 2
  • Patients with panic disorder may have higher free T4 levels compared to other psychiatric conditions 1
  • Hyperthyroidism can present with or worsen anxiety symptoms 3

• Complete Blood Count (CBC)

  • To evaluate for anemia, infection, or other hematologic abnormalities that may contribute to anxiety symptoms 1

• Comprehensive Metabolic Panel (CMP)

  • To assess electrolytes, glucose, kidney and liver function 1
  • Metabolic disturbances can present with or worsen anxiety symptoms 1

Conditional Tests

• Urine Drug Screen
  • Not routinely recommended for all patients with anxiety 2
  • Consider only when substance use is suspected based on history or presentation
  • Low yield when performed routinely in alert, cooperative patients with normal vital signs 2

Assessment Tools to Complement Laboratory Testing

• Generalized Anxiety Disorder-7 (GAD-7)

  • 7-item self-report scale with excellent validity 1
  • Scores ≥10 suggest moderate anxiety; scores ≥15 suggest severe anxiety 2, 1
  • Sensitivity of 89% and specificity of 82% 1, 4
  • Estimated minimally important difference (MID) is 3 points 4

• GAD-2 (Ultra-short version)

  • Rapid initial screening tool
  • Positive screen defined as score ≥3 points 1

Special Considerations

Gender Differences

• Women are twice as likely to experience anxiety disorders compared to men 1, 3
• Consider hormonal fluctuations in the evaluation of anxiety in women 1

Comorbid Conditions

• Screen for depression, as anxiety disorders frequently co-occur with depression 1, 5
• Consider additional testing for patients with comorbid medical conditions 2
• Thyroid disorders affect anxiety prevalence:
  • Hyperthyroid patients have higher prevalence of anxiety (64.1%) compared to hypothyroid patients (44.4%) 3

Interpretation and Follow-up

• Abnormal thyroid function may require dose adjustment of thyroid medication and follow-up testing in 6-8 weeks 1
• Use standardized anxiety assessment tools like GAD-7 to objectively track symptoms over time 1, 4
• Consider referral to psychiatry for moderate to severe anxiety (GAD-7 score ≥10) 2

Common Pitfalls to Avoid

• Overreliance on laboratory testing: Extensive, routine laboratory testing has been shown to be unnecessary and can lead to false positives 2
• Underscreening for thyroid disorders: Given the significant comorbidity between anxiety and thyroid dysfunction, thyroid function tests should be routinely performed 2, 1
• Ignoring physical symptoms: Anxiety disorders are associated with physical symptoms such as palpitations, shortness of breath, and dizziness that may be mistaken for other medical conditions 6
• Missing comorbid conditions: Anxiety disorders often co-occur with depression, substance use disorders, and personality disorders 5

Remember that laboratory testing should be directed by history and physical examination, as routine extensive testing has low yield and can lead to false positives 2.