What laboratory tests should be ordered for a 35‑year‑old woman with marked anxiety and a fear of taking medications to rule out underlying medical causes?

Laboratory Testing for Anxiety in a 35-Year-Old Woman

Before diagnosing primary anxiety disorder, you must rule out medical causes including thyroid disease, cardiac disorders, respiratory conditions, and drug-related effects through targeted laboratory testing. 1, 2

Essential Laboratory Tests

The following labs should be ordered to exclude medical mimics of anxiety:

Thyroid Function

• Thyroid-stimulating hormone (TSH) and free T4 – Hyperthyroidism directly mimics anxiety disorder symptoms with palpitations, tremor, and excessive worry 1, 2

Metabolic Panel

• Complete metabolic panel (CMP) – Identifies electrolyte disturbances (particularly calcium and glucose abnormalities) that can present as anxiety 1
• Blood glucose specifically rules out hypoglycemia, which causes anxiety-like symptoms 1

Hematologic Testing

• Complete blood count (CBC) with differential – Detects anemia, which can cause fatigue, palpitations, and anxiety-like symptoms 1

Additional Screening

• Urinalysis – Rules out urinary tract infection, which can present with agitation and anxiety, particularly if undiagnosed 1

Clinical Reasoning

The Women's Preventive Services Initiative explicitly states that diagnosis of anxiety disorder requires meeting DSM criteria after ruling out alternative causes such as thyroid disease or drug use 1. This 35-year-old woman falls squarely within the peak prevalence age for anxiety disorders (lifetime prevalence ~40% in women), but medical causes must be excluded first 1.

Why These Specific Tests

• Thyroid disease is the most common medical mimic of anxiety and must be ruled out in every anxious patient 1, 2
• Electrolyte abnormalities (hypercalcemia, hypoglycemia) produce identical symptoms to anxiety disorders 1
• Anemia causes compensatory tachycardia and dyspnea that patients interpret as anxiety 1
• Infections (particularly UTI) can present with behavioral changes including anxiety 1

What NOT to Order

Do not order extensive endocrine panels, cardiac biomarkers, or imaging studies unless history and physical examination suggest specific pathology. The goal is targeted exclusion of common medical mimics, not exhaustive testing that may reinforce health anxiety in an already fearful patient.

Next Steps After Lab Results

Once medical causes are excluded:

• Use GAD-7 screening tool (sensitivity 57.6-93.9%, specificity 61-97%) to quantify anxiety severity 3
• Screen for depression using PHQ-9, as 56% of anxiety patients have comorbid depression 1
• Assess for substance use including caffeine, stimulants, and alcohol, all of which cause or exacerbate anxiety 2

Treatment Approach for Medication-Fearful Patients

Given this patient's fear of medications, cognitive behavioral therapy (CBT) should be offered as first-line treatment before pharmacotherapy 1. CBT demonstrates large effect sizes (Hedges g = 1.01 for generalized anxiety disorder) and has no medication-related adverse effects 3. The Women's Preventive Services Initiative explicitly states that CBT and other psychotherapies are initial treatments for most patients, with medications (SSRIs/SNRIs) being secondary 1.

Common Pitfalls

• Do not skip medical workup even in young, healthy-appearing patients – thyroid disease and other medical causes are frequently missed 1, 2
• Do not order excessive testing that reinforces somatic preoccupation in anxious patients 1
• Do not delay treatment while waiting for lab results if symptoms are severe – CBT referral can begin immediately 4
• Do not assume anxiety is "just stress" without formal screening and medical exclusion 1