Initial Assessment of Suspected Fibromyalgia
The initial assessment of suspected fibromyalgia requires documenting chronic widespread pain in all four body quadrants for at least 3 months, examining 18 specific tender points (with at least 11 positive), assessing associated symptoms (fatigue, sleep disturbances, cognitive dysfunction), and performing targeted laboratory testing to exclude mimicking conditions—not to confirm fibromyalgia itself. 1, 2
Clinical History Requirements
Pain Characteristics
- Document pain duration of at least 3 months in all four body quadrants (upper/lower, left/right) 1, 3
- Assess for hyperalgesia (increased pain response) and allodynia (pain from normally non-painful stimuli) 1
- Quantify pain intensity using the Visual Analogue Scale (VAS) 1
Associated Symptom Assessment
- Fatigue: Specifically ask about fatigue that is disproportionate to activity level 1
- Sleep disturbances: Document non-restorative sleep patterns 1, 2
- Cognitive dysfunction: Assess for "fibro fog" and concentration difficulties 1, 2
- Mood disturbances: Screen for anxiety and depression, which are common comorbidities 1, 4
Environmental and Medication History
- Inquire about triggers: alcohol, sleep deprivation, emotional stress, large meals, caffeine, and exercise 1
- Obtain careful history of current and past medications, as certain drugs can cause or exacerbate widespread pain 5
Physical Examination
Tender Point Examination
- Examine 18 specific bilateral tender points (9 pairs) at these anatomical locations 1:
- Occiput (suboccipital muscle insertions)
- Lower cervical spine (anterior aspects of C5-C7 intertransverse spaces)
- Trapezius (midpoint of upper border)
- Supraspinatus (above scapular spine near medial border)
- Second rib (second costochondral junctions)
- Lateral epicondyle (2 cm distal to epicondyles)
- Gluteus (upper outer quadrants of buttocks)
- Greater trochanter (posterior to trochanteric prominence)
- Knee (medial fat pad proximal to joint line)
Examination Technique
- Apply approximately 4 kg of pressure (sufficient to blanch your fingernail bed) 1
- A tender point is positive only when the patient reports pain, not just sensitivity 1
- Diagnosis requires pain in at least 11 of 18 tender points 1, 3
Alternative Diagnostic Approach (2010 ACR Criteria)
If tender point examination is impractical, use the Widespread Pain Index (WPI) and Symptom Severity (SS) scale 2:
- WPI: Count the number of painful body regions (0-19)
- SS scale: Sum scores for cognitive symptoms, unrefreshed sleep, fatigue, and somatic symptoms (0-12)
- Diagnostic criteria: (WPI ≥7 AND SS ≥5) OR (WPI 3-6 AND SS ≥9) 2
Laboratory Testing to Exclude Mimicking Conditions
Essential Laboratory Panel
Perform these tests to rule out inflammatory, endocrine, and systemic diseases—not to confirm fibromyalgia 1, 5:
- Complete blood count 1, 5
- Erythrocyte sedimentation rate (ESR) 1
- C-reactive protein (CRP) 1
- Thyroid-stimulating hormone (TSH) 1, 5
- Serum electrolytes (including calcium and magnesium) 5
- Blood urea nitrogen and serum creatinine 5
- Fasting blood glucose 5
- Liver function tests 5
- Creatine kinase (if myopathy suspected) 1, 5
- Vitamin D levels 1
- Urinalysis 5
Additional Testing Based on Clinical Suspicion
- Consider inflammatory markers if rheumatologic conditions are suspected 5
- Chest X-ray and abdominal ultrasonography as first-line general evaluation 6
Functional Impact Assessment
Standardized Questionnaires
- Fibromyalgia Impact Questionnaire (FIQ): Measures functional impairment in daily activities, pain, fatigue, sleep quality, and overall functioning 1
- This assessment is crucial for establishing baseline severity and monitoring treatment response 1
Differential Diagnosis Considerations
Overlapping Conditions to Screen For
- Chronic fatigue syndrome: May coexist or present similarly 1
- Post-Lyme disease syndrome: Can present with multiple tender points and widespread pain 1
- Irritable bowel syndrome: Frequently comorbid 4
- Migraine: Common overlapping condition 1
- Primary mood disorders: Carefully evaluate for depression and anxiety as primary diagnoses rather than secondary symptoms 4
Common Pitfalls to Avoid
- Do not rely solely on tender points: Approximately 25% of fibromyalgia patients may not satisfy tender point criteria at any given time due to symptom variability 2
- Avoid over-testing: Fibromyalgia does not involve organic damage; extensive imaging and specialized testing are not indicated unless specific alternative diagnoses are suspected 3, 6
- Recognize diagnostic delay: Average diagnosis takes over 2 years with 3.7 physician consultations, leading to high healthcare utilization 1
- Consider comorbidities: Fibromyalgia as a standalone diagnosis is rare; most patients meet criteria for other chronic overlapping pain conditions or mental disorders 7