Laboratory Workup for 45-Year-Old Female with Anxiety and Fatigue
For a 45-year-old woman presenting with anxiety and fatigue, obtain thyroid-stimulating hormone (TSH), complete blood count (CBC), and comprehensive metabolic panel (CMP) as the essential initial laboratory tests. 1
Core Laboratory Studies
The following tests should be ordered to evaluate common medical causes of anxiety and fatigue:
TSH (thyroid-stimulating hormone): Thyroid dysfunction is strongly associated with anxiety disorders and must be ruled out, as both hypothyroidism and hyperthyroidism can present with anxiety symptoms and fatigue 2, 1
Complete blood count (CBC) with differential: Evaluates for anemia, infection, or hematologic abnormalities that commonly cause fatigue 1, 3
Comprehensive metabolic panel (CMP): Assesses liver and kidney function, electrolyte imbalances, and glucose abnormalities that can manifest as both anxiety and fatigue 1
Additional Considerations Based on Clinical Context
Inflammatory markers (ESR/CRP): Consider if there are concerns for inflammatory conditions or autoimmune disease contributing to symptoms 1
Iron studies: Even with normal hemoglobin, iron deficiency can cause significant fatigue and should be evaluated if clinical suspicion exists 3
Vitamin D and B12 levels: Nutritional deficiencies may contribute to fatigue, though these are secondary considerations 3
Clinical Assessment Framework
Before ordering labs, complete a structured symptom assessment:
Quantify fatigue severity using a 0-10 numeric scale, where scores of 4-10 warrant focused evaluation 4, 1, 3
Screen anxiety severity using the GAD-7 scale (scores ≥8-9 indicate clinically significant anxiety) or the ultra-brief GAD-2 (scores ≥3 warrant further evaluation) 2
Assess onset, pattern, duration, and changes over time for both anxiety and fatigue to identify temporal relationships 4, 1
Evaluate sleep quality, quantity, and sleep hygiene, as sleep disturbance commonly links anxiety and fatigue 4, 1, 3
Review all medications (prescription, over-the-counter, supplements) as medication side effects are frequently overlooked contributors to both symptoms 4, 1
Screen for depression, which co-occurs in approximately 56% of patients with anxiety disorders and frequently clusters with fatigue 2, 5, 6
Important Clinical Pitfalls
Do not assume anxiety is purely psychological without ruling out thyroid disease, as studies show 2-10% of anxiety disorder patients have underlying thyroid dysfunction, with higher rates in generalized anxiety disorder specifically 2. The relationship between anxiety and thyroid dysfunction is bidirectional and clinically significant 2.
Recognize that anxiety and fatigue commonly co-occur through environmental rather than genetic mechanisms, meaning they often share common triggers or maintaining factors that should be addressed simultaneously 6, 7. Up to three-quarters of patients with chronic fatigue have comorbid anxiety or mood disorders 6.
Avoid extensive unnecessary testing if initial workup is normal and symptoms align with primary anxiety disorder, as anxiety disorders affect 34% of adults and are associated with significant somatic symptoms including fatigue, palpitations, and dizziness 5.