What basic laboratory tests should be ordered for a 13-year-old patient presenting with anxiety and depression?

Laboratory Testing for Adolescent Anxiety and Depression

Laboratory testing is NOT routinely indicated for a 13-year-old presenting with anxiety and depression unless specific signs or symptoms suggest an underlying medical condition. 1

When to Order Labs

The 2020 AACAP anxiety guideline explicitly states that laboratory testing is not routine in the evaluation of a suspected anxiety disorder 1. Testing should only be completed in collaboration with the primary care practitioner when signs and symptoms suggest a specific medical condition 1.

Specific Medical "Masqueraders" to Consider

Order targeted labs only if clinical assessment suggests:

• Thyroid function tests (TSH, free T4): If signs of hyperthyroidism present (weight loss, tremor, heat intolerance, tachycardia)
• Glucose/HbA1c: If symptoms suggest diabetes or hypoglycemic episodes
• Complete blood count: If fatigue suggests anemia or if there are signs of systemic illness
• Lead level: Only if exposure history or developmental concerns exist
• Urine drug screen: If substance use is suspected based on history or presentation

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The Evidence Against Routine Screening

Research strongly supports this selective approach. A 2015 study of over 1,000 pediatric psychiatric patients in emergency departments found that 94.3% of patients with non-concerning clinical examinations also had clinically nonsignificant test results 2. Routine comprehensive laboratory panels in this population could waste up to $90 million annually without improving detection of emergency medical conditions 2.

A 1992 review confirmed that widespread use of extensive screening batteries (CBC, comprehensive metabolic panel, ESR, B12, folate, EEG, EKG, chest X-ray) is not indicated in the majority of psychiatric patients, as most abnormal findings are clinically insignificant and don't affect management 3.

The Clinical Assessment Priority

The diagnostic evaluation should focus on comprehensive clinical assessment rather than laboratory screening 4. This includes:

• Direct interviews with patient and family
• Assessment using standardized depression and anxiety rating scales
• Evaluation of functional impairment across school, home, and peer settings
• Screening for psychiatric comorbidities
• Safety assessment including suicide risk
• Collateral information from teachers or other sources

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Common Pitfall to Avoid

The most common error is ordering routine "medical clearance" laboratory panels without clinical indication. This practice:

• Generates false-positive results requiring unnecessary follow-up
• Increases costs substantially
• Does not improve diagnostic accuracy when clinical examination is non-concerning
• Delays appropriate psychiatric treatment

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Bottom Line Algorithm

1. Perform thorough history and physical examination looking specifically for signs/symptoms of medical conditions associated with anxiety/depression
2. If examination is non-concerning: No labs needed—proceed with psychiatric assessment and treatment
3. If specific medical concerns identified: Order only the targeted tests relevant to those concerns (e.g., thyroid function if hyperthyroid symptoms present)
4. Focus resources on validated screening instruments (PHQ-9, GAD-7) and comprehensive psychiatric evaluation rather than laboratory testing

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