What tests are recommended for fatigue and night sweats?

Diagnostic Testing for Fatigue and Night Sweats

For patients presenting with fatigue and night sweats, a focused evaluation should include tuberculosis screening, complete blood count, comprehensive metabolic panel, thyroid function tests, HIV testing, and chest radiography to rule out common serious causes.

Initial Evaluation

History and Physical Examination Focus Points

• Assess for constitutional symptoms including fever, weight loss (>10% of body weight over 6 months), and duration of fatigue 1
• Evaluate for specific tuberculosis risk factors: close contact with TB patients, time spent in TB-endemic countries, or exposure in high-risk settings (prisons, homeless shelters, long-term care facilities) 1
• Document duration and pattern of night sweats (timing, severity, associated symptoms) 2
• Screen for respiratory symptoms, particularly cough lasting >2 weeks 1
• Assess for lymphadenopathy, especially cervical, axillary, or inguinal regions 1

First-Line Laboratory Testing

• Complete blood count with differential to evaluate for infection, malignancy, and anemia 1, 2
• Comprehensive metabolic panel including liver and kidney function tests 1, 2
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) as inflammatory markers 1
• Thyroid-stimulating hormone (TSH) to rule out hyperthyroidism 2
• HIV testing, particularly in high-risk individuals 1, 2
• Tuberculin skin test (PPD) or interferon-gamma release assay (IGRA), especially in high-risk populations 1

Imaging Studies

• Chest radiography for all patients with fatigue and night sweats, particularly when respiratory symptoms are present 1
• Consider chest CT for patients with abnormal chest radiographs or high clinical suspicion despite normal radiographs, especially in immunocompromised patients 1

Additional Testing Based on Initial Findings

If Tuberculosis Is Suspected

• Collect at least three sputum specimens (on separate days) for acid-fast bacilli (AFB) smear, culture, and drug susceptibility testing 1
• Consider Xpert MTB/RIF testing when available, particularly in high TB prevalence settings or for patients at risk of drug-resistant TB 1
• Evaluate for both pulmonary and extrapulmonary TB manifestations 1

If Malignancy Is Suspected

• Consider lymphoma workup including additional imaging (CT abdomen/pelvis) 1, 2
• Evaluate for B symptoms: fever, night sweats, and weight loss >10% of body weight 1
• Consider bone marrow biopsy if blood counts are abnormal 1, 2

If Autoimmune/Inflammatory Conditions Are Suspected

• Additional autoimmune markers such as antinuclear antibodies (ANA) and rheumatoid factor (RF) 1
• Consider evaluation for large vessel vasculitis in patients with constitutional symptoms and vascular findings 1

Special Considerations

For Chronic Fatigue

• Rule out common contributing factors such as sleep disturbances, pain, emotional distress, and medication side effects 1, 3
• Consider activity enhancement and energy conservation strategies for management 1
• Screen for depression and anxiety as potential causes or contributors 3

For Night Sweats

• Consider non-infectious causes including medications (antihypertensives, antipyretics), gastroesophageal reflux disease, obstructive sleep apnea, and hypoglycemia 2, 4
• Evaluate medication list for potential contributors to night sweats 2
• Remember that night sweats alone are nonspecific and may not indicate serious pathology 4

Common Pitfalls to Avoid

• Don't assume night sweats are always due to infection or malignancy; they are often nonspecific 4
• Avoid extensive "fishing expeditions" if initial workup is negative and symptoms are chronic 5
• Remember that elderly patients with TB may present atypically with fewer classic symptoms 1
• Don't delay evaluation in patients with high-risk features (weight loss, persistent fever, lymphadenopathy) 6
• Consider that psychiatric illness, such as depression or anxiety, can cause fatigue but should be a diagnosis of inclusion, not exclusion 5, 3