What is the appropriate workup for a [AGE] year old patient presenting with chronic fatigue?

Workup for Chronic Fatigue in Adults

Begin by screening fatigue severity using a 0-10 numeric scale, then pursue focused evaluation only if the score is ≥4 (moderate to severe), targeting treatable contributing factors before ordering extensive laboratory testing. 1, 2

Initial Severity Assessment

• Ask the patient: "How would you rate your fatigue on a scale of 0 to 10 over the past 7 days?" 3
• Alternatively, use categorical assessment: none, mild, moderate, or severe 3, 1
• Scores 0-3 (mild): No further workup needed—rescreen at regular intervals only 3, 1
• Scores 4-10 (moderate to severe): Proceed with focused evaluation 3, 2
• Note that scores ≥7 correlate with marked functional impairment 3, 1

Focused History (For Moderate to Severe Fatigue)

Document the following specific characteristics:

• Temporal pattern: Onset timing, duration, progression, and relationship to any triggering events 1, 2
• Functional impact: Specific limitations in work, social activities, and daily self-care 1, 4
• Associated symptoms: Pain, sleep disturbance, cognitive difficulties, muscle/joint pain, sore throat, tender lymph nodes, headaches, postexertional malaise 3, 5, 4
• Aggravating/alleviating factors: What makes fatigue worse or better 1
• Patient's attribution: Their own understanding of what is causing the fatigue 6

Assessment of Treatable Contributing Factors

This is the most critical step—address these before pursuing extensive testing:

Pain Assessment

• Evaluate for chronic pain conditions, as pain commonly clusters with fatigue 1, 2
• Treat pain effectively as initial management strategy 3, 2

Emotional Distress Screening

• Screen specifically for depression and anxiety, which frequently co-occur with fatigue 3, 1, 2
• Depression and anxiety account for a significant proportion of chronic fatigue cases 7, 8
• This is not a diagnosis of exclusion—suspect based on history 7

Sleep Evaluation

• Assess sleep quality, quantity, and sleep hygiene practices 3, 1, 2
• Screen for sleep disorders including sleep apnea and insomnia 2
• Evaluate sleep environment and pre-bedtime routines 2

Medication Review

• Review ALL medications including over-the-counter drugs, herbal supplements, and vitamins 3, 1, 2
• Note recent medication changes 2
• Evaluate for drug interactions causing excessive drowsiness 2
• Consider specific culprits like β-blockers that may cause bradycardia and fatigue 2

Substance Use

• Screen for alcohol or substance misuse 1, 2

Activity and Nutrition

• Assess changes in exercise patterns and current conditioning level 2
• Evaluate weight changes, caloric intake, and appetite 2
• Check for fluid and electrolyte imbalances 2

Laboratory Workup

Order these screening tests for moderate to severe fatigue:

• Complete blood count with differential (anemia, infection, malignancy) 2
• Comprehensive metabolic panel (liver/kidney function, electrolytes) 2
• Thyroid-stimulating hormone (TSH) for thyroid dysfunction 3, 2
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) for inflammation 2
• Consider HIV testing and tuberculosis screening if risk factors present 2

Important caveat: If medical illness is causing fatigue, it is usually evident on initial presentation with history and physical examination 7. Further "fishing expeditions" beyond basic screening are fruitless if initial evaluation is unrevealing 7.

Physical Examination

Focus on systems suggested by history:

• Cardiopulmonary examination 4
• Neurologic examination 4
• Skin examination 4
• Lymph node assessment 5
• Thyroid palpation 3

Special Considerations for Specific Populations

Cancer Survivors

• Mild to moderate fatigue persisting 6-12 months post-treatment does not warrant extensive workup unless other symptoms present 3
• Moderate to severe fatigue that begins or worsens after treatment completion requires extensive workup for metastatic disease 3
• Red flag symptoms requiring immediate investigation: pain, pulmonary complaints, unintentional weight loss 3
• Include echocardiogram if patient received cardiotoxic treatments 3
• Include thyroid screening if patient received radiation to neck or thorax 3

When to Consider Chronic Fatigue Syndrome (ME/CFS)

Only consider this diagnosis after excluding other causes:

• Severe fatigue lasting >6 months not relieved by rest 5, 4
• Presence of ≥4 of the following: postexertional malaise, unrefreshing sleep, impaired memory/concentration, muscle pain, polyarthralgia, sore throat, tender lymph nodes, new headaches 5, 4
• Postexertional malaise is the most important diagnostic symptom 4
• This is a clinical diagnosis made only when other disease processes are excluded 5

Common Pitfalls to Avoid

• Do not overlook medication side effects as contributors to fatigue 1, 2
• Do not pursue extensive testing if initial history, examination, and basic labs are unrevealing 7
• Do not treat fatigue as a diagnosis of exclusion—actively look for psychiatric causes based on history 7
• Remember that fatigue rarely occurs in isolation and often clusters with other symptoms 1, 2
• Do not recommend exercise therapy for patients with ME/CFS, as it can trigger postexertional malaise and cause harm 4