Laboratory Testing for Anxiety Disorders

Recommended Initial Laboratory Tests

The American College of Cardiology is not relevant here, however, routine thyroid screening (TSH) should be performed when evaluating patients presenting with anxiety disorders, as there is significant comorbidity between anxiety and thyroid dysfunction 1, 2, 3
TSH (thyroid-stimulating hormone) is the primary recommended screening test for patients with anxiety disorders 1, 2, 3
Free T4 (fT4) should be added if TSH is abnormal or if clinical suspicion for thyroid disease is high 1, 4
The comorbidity between anxiety disorders and thyroid disorders is significant enough to warrant routine screening 1, 2, 3
Subclinical thyroid dysfunction has been documented in anxiety patients, with blunted TSH responses and inverse relationships between anxiety levels and TSH 1, 2, 3

Laboratory testing beyond thyroid function should be guided by clinical evaluation rather than routine screening, as recommended by the American Academy of Emergency Medicine 5
Routine extensive laboratory batteries are not recommended for all anxiety patients 5
Selective testing should be based on patient history and physical examination findings, presence of medical symptoms or vital sign abnormalities, first-time psychiatric presentation, elderly patients, substance abuse history, or new medical complaints 5

Medical or substance-induced causes of anxiety symptoms should be investigated, considering age, sex, BMI, smoking status, and comorbid depression 6, 7, 1, 2
Consider screening for substance use disorders, as these commonly co-occur with anxiety 8, 6

For a patient presenting with anxiety, obtain TSH as the primary screening test, and add free T4 if TSH is abnormal, as recommended by the American Psychiatric Association 1, 2, 3, 4
Perform additional laboratory testing only when guided by specific clinical findings from history and physical examination, to avoid routine extensive laboratory panels 5
The evidence does not support routine screening beyond thyroid function unless specific clinical indicators are present, according to the American Academy of Emergency Medicine 5

The American College of Physicians recommends using PHQ-9 as the primary screening tool for depressive symptoms, with scores ≥10 indicating moderate to severe depression requiring further diagnostic assessment 9, 10
The American Psychological Association suggests using GAD-7 as the primary screening tool for anxiety symptoms, with scores 0-4 indicating none/mild symptoms, scores 5-9 indicating moderate symptoms, scores 10-14 indicating moderate to severe symptoms, and scores 15-21 indicating severe symptoms requiring referral to mental health professionals 10, 11
Initial screening should assess for risk of harm to self or others, with immediate referral for emergency psychiatric evaluation if suicidal ideation or self-harm risk is identified 12, 13

The National Institute of Mental Health recommends assessing for medical causes of depressive symptoms, such as unrelieved pain, fatigue, or delirium from infection or electrolyte imbalance, before attributing symptoms solely to psychiatric illness 12, 13
Medical or substance-induced causes, such as interferon administration, corticosteroids, or thyroid dysfunction, should be determined and treated 9, 10

A practical algorithm for initial assessment and screening involves screening with PHQ-9 and GAD-7 at initial presentation, ordering TSH on all patients, and assessing for medical causes of symptoms including pain, fatigue, infection, or medication effects 9, 10, 11, 12, 13