What are the basic investigations for a patient presenting with generalized body pain?

Basic Investigations for Generalized Body Pain

The basic investigations for a patient presenting with generalized body pain should include complete blood count, inflammatory markers (ESR and CRP), comprehensive metabolic panel, and targeted testing based on clinical suspicion.

Initial Laboratory Investigations

Essential Blood Tests

• Complete Blood Count (CBC) 1

  • Evaluates for anemia, leukocytosis (infection/inflammation), thrombocytosis
  • Abnormalities may indicate underlying inflammatory or infectious processes

• Inflammatory Markers 1, 2

  • C-reactive protein (CRP): More sensitive for acute inflammation
  • Erythrocyte sedimentation rate (ESR): Better for chronic inflammation
  • Combined interpretation provides better diagnostic information:

    CRP	ESR	Interpretation
    Elevated	Normal	Acute inflammation
    Normal	Elevated	Chronic inflammation
    Elevated	Elevated	Active inflammation
    Normal	Normal	Low likelihood of significant inflammation

• Comprehensive Metabolic Panel 1, 2

  • Electrolytes (sodium, potassium, calcium, magnesium)
  • Renal function (BUN, creatinine)
  • Liver enzymes
  • Albumin and pre-albumin (nutritional status and inflammation)

Additional First-Line Tests

• Stool cultures and Clostridium difficile toxin test (if GI symptoms present) 1
• Fecal calprotectin (when IBD is suspected) 1
• Urinalysis (to rule out renal causes)
• Thyroid function tests (TSH, free T4)

Specialized Testing Based on Clinical Suspicion

Infectious Disease Workup

• Blood cultures (if fever present)
• Specific viral serologies (e.g., EBV, CMV, HIV) based on clinical presentation 1

Rheumatologic Evaluation

• Rheumatoid factor
• Anti-nuclear antibody (ANA)
• Anti-CCP antibodies
• Complement levels

Medication-Related Considerations

• Medication review for potential drug interactions or serotonin syndrome 3
• Toxicology screen if substance use is suspected

Imaging Studies

Initial Imaging

• Plain radiographs of affected areas if localized pain is predominant 1
• Chest X-ray if respiratory symptoms are present

Advanced Imaging (if indicated)

• MRI for suspected inflammatory or neurological conditions
• CT scan if abscess, perforation, or other acute complications are suspected 1
• Ultrasound for soft tissue pathology assessment

Special Considerations

Pain Pattern Assessment

• Document pain distribution using body diagrams 4, 5
• Assess for pain qualities suggesting specific etiologies:
  • Aching/throbbing: Often associated with somatic pain 1
  • Cramping/gnawing: Often associated with visceral pain 1
  • Shooting/tingling: Often associated with neuropathic pain 1

Psychosocial Assessment

• Psychological screening tools for depression, anxiety, and catastrophizing 1
• Pain interference assessment with daily activities, sleep, and quality of life 1

Clinical Pearls and Pitfalls

Important Clinical Pearls

• Normal inflammatory markers do not completely rule out inflammatory conditions; approximately 4% of patients with confirmed inflammatory conditions may have normal ESR and CRP 6
• The combination of CRP and ESR provides better diagnostic information than either test alone 2
• Consider medication-induced pain syndromes, particularly serotonin syndrome in patients on multiple serotonergic medications 3

Common Pitfalls to Avoid

• Treating laboratory values rather than the patient's symptoms
• Overlooking non-inflammatory causes of generalized pain when inflammatory markers are normal
• Failing to assess for psychosocial factors that may amplify pain perception 1
• Premature use of opioids for chronic generalized pain 1
• Missing underlying substance use disorders that may contribute to pain presentation

By systematically approaching generalized body pain with these investigations, clinicians can effectively identify underlying causes and develop appropriate treatment strategies focused on improving patient outcomes and quality of life.