What bloodwork is recommended for evaluating inflammation?

Recommended Bloodwork for Evaluating Inflammation

The core laboratory tests for evaluating inflammation should include C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and complete blood count (CBC) with differential. 1, 2

First-Line Inflammatory Markers

C-Reactive Protein (CRP)

• Rises rapidly (within 4-6 hours) in acute inflammation
• Peaks at 24-48 hours
• Short half-life (19 hours) makes it excellent for monitoring acute inflammatory responses
• Normal value: <5 mg/L
• More sensitive for acute inflammation than ESR
• Particularly useful for:
  • Detecting active inflammation
  • Monitoring treatment response
  • Distinguishing between active disease and remission 2, 3

Erythrocyte Sedimentation Rate (ESR)

• Rises more slowly than CRP (24-48 hours)
• Remains elevated for longer periods (weeks)
• Affected by age, gender, anemia, and plasma proteins
• Normal values vary by age and sex:
  • Men: age/2 mm/hr
  • Women: (age+10)/2 mm/hr
• Better for monitoring chronic inflammatory conditions
• Complements CRP in evaluating inflammatory status 3, 4

Complete Blood Count (CBC) with Differential

• Evaluates for leukocytosis (elevated white blood cells)
• Assesses for anemia (common in chronic inflammation)
• Checks for thrombocytosis (elevated platelets in inflammation)
• Provides differential count to identify specific inflammatory cell types 1, 2

Interpretation of Combined Inflammatory Markers

CRP	ESR	Interpretation
Elevated	Normal	Acute inflammation
Normal	Elevated	Chronic inflammation or non-inflammatory factors
Elevated	Elevated	Active inflammation
Normal	Normal	Low likelihood of significant inflammation [2,4]

Second-Line Tests Based on Clinical Context

For Rheumatologic Conditions

• Serum albumin (decreased in chronic inflammation)
• Autoimmune panels (based on suspected condition)
• Specific autoantibodies (e.g., rheumatoid factor, anti-CCP)
• Muscle enzymes (CK, LDH, aldolase) for suspected myositis 1

For Gastrointestinal Inflammation

• Fecal calprotectin:
  • <50 mg/g: High sensitivity (88%) for ruling out inflammation
  • <150 mg/g: Recommended to rule out active inflammation

  • 250 mg/g: Higher specificity (74%) for active inflammation

• Fecal lactoferrin (normal <7.25 mg/g) 1, 2

For Suspected Autoinflammatory Disorders

• Serum amyloid A (SAA)
• S100 proteins
• Genetic testing as appropriate 1

Important Considerations and Limitations

• CRP limitations: Normal CRP does not rule out inflammation - studies show histological evidence of inflammation in nearly 50% of patients with normal CRP 5

• ESR limitations: Affected by non-inflammatory factors including:

  • Age and gender
  • Anemia
  • Hypergammaglobulinemia
  • Pregnancy
  • Obesity 4

• Combined testing: Using both CRP and ESR improves diagnostic yield, as they reflect different aspects of the inflammatory response 3, 4

• Cost-effectiveness: The combination of CRP and WBC count provides the best cost-effectiveness for initial evaluation 6

• Clinical context: Interpret results in the context of clinical presentation - inflammatory markers alone have limited sensitivity and specificity 7

Algorithm for Inflammatory Workup

1. Initial evaluation: Order CRP, ESR, and CBC with differential
2. If elevated markers: Proceed with targeted testing based on clinical presentation
3. If normal markers but high clinical suspicion: Consider second-line tests and specialty referral
4. For monitoring:
   • Use CRP for acute conditions and treatment response
   • Use ESR for chronic inflammatory conditions
   • Repeat at appropriate intervals (3-6 months for chronic conditions)

Remember that while these tests are valuable tools, they should be interpreted in the context of the patient's clinical presentation, as they lack specificity for any particular disease process.