What does an elevated sed (erythrocyte sedimentation) rate indicate and how is it managed?

Elevated Erythrocyte Sedimentation Rate (ESR): Clinical Significance and Management

An elevated erythrocyte sedimentation rate (ESR) is a non-specific marker of inflammation that indicates the presence of an underlying inflammatory, infectious, malignant, or autoimmune condition requiring further diagnostic evaluation based on clinical context. 1, 2

What ESR Measures and How It Works

• ESR is a measure of blood viscosity and serves as a surrogate marker of inflammation
• It measures the rate at which red blood cells settle in a tube of anticoagulated blood over one hour
• Normal values vary by age and gender:
  • Men: <15 mm/hr (under 50 years), <20 mm/hr (over 50 years)
  • Women: <20 mm/hr (under 50 years), <30 mm/hr (over 50 years)

Clinical Significance of Elevated ESR

Common Causes of Markedly Elevated ESR (>70 mm/hr)

• Infections (42% of cases) 3
• Malignancies (27% of cases) 3
• Inflammatory/autoimmune disorders (20% of cases) 3
• Only 5% of markedly elevated ESR values remain unexplained 3

Specific Conditions Associated with Elevated ESR

1. Rheumatologic conditions:

   • Rheumatoid arthritis - ESR helps monitor disease activity 1
   • Polymyalgia rheumatica - typically ESR >40 mm/hr, though 20.4% of patients may have lower values 4
   • Temporal arteritis - ESR is crucial for diagnosis and monitoring treatment response 5

2. Infectious diseases:

   • Bacterial infections
   • Osteomyelitis - ESR is suggestive when markedly elevated 1
   • Prosthetic joint infections - elevated ESR (>35 mm/hr) is common 1

3. Inflammatory bowel disease:

   • Ulcerative colitis - ESR >30 mm/hr suggests active disease 1
   • Crohn's disease - ESR helps assess inflammation 6

4. Malignancies:

   • Hodgkin's lymphoma - elevated ESR is a risk factor for disease progression 1
   • Multiple myeloma
   • Metastatic cancer

ESR vs. CRP: When to Use Each

• ESR advantages:

  • Better for monitoring chronic inflammatory conditions (fibrinogen has longer half-life)
  • More stable, less affected by acute changes
  • Better for conditions like temporal arteritis, polymyalgia rheumatica

• CRP advantages:

  • Rises and falls more quickly (4-6 hour response time)
  • Better for acute inflammation and infection monitoring
  • More specific for bacterial infections
  • Better for monitoring treatment response in acute conditions 7

Limitations and Pitfalls

• Low sensitivity and specificity:

  • ESR can be normal in patients with cancer, infection, and connective tissue disease 5
  • Not useful as a screening test in asymptomatic individuals 5

• Factors affecting ESR values:

  • Age (increases with age)
  • Gender (higher in women)
  • Pregnancy (elevated)
  • Anemia (elevated)
  • Polycythemia (decreased)
  • Medications (oral contraceptives, statins can increase)
  • Technical factors (temperature, tube tilt)

• Discordance with CRP:

  • ESR may remain elevated while CRP normalizes during recovery
  • Conditions like SLE may show high ESR with normal CRP 2

Management Approach for Elevated ESR

1. Interpret in clinical context:

   • An isolated elevated ESR without symptoms rarely indicates serious disease
   • ESR should not be used as a standalone screening test 5

2. Evaluate based on degree of elevation:

   • Mild elevation (20-30 mm/hr): Often non-specific
   • Moderate elevation (30-70 mm/hr): Consider inflammatory conditions
   • Marked elevation (>70 mm/hr): High likelihood of significant pathology 3

3. Targeted workup based on clinical presentation:

   • Joint symptoms: Consider rheumatoid arthritis, polymyalgia rheumatica
   • Fever: Investigate infections, malignancies
   • Headache in older adults: Evaluate for temporal arteritis
   • Abdominal symptoms: Consider inflammatory bowel disease
   • Weight loss, night sweats: Consider malignancy, especially lymphoma

4. Follow-up and monitoring:

   • Serial ESR measurements are useful for monitoring disease activity and treatment response
   • Consider both ESR and CRP for complementary information
   • Normal ESR and CRP together have high negative predictive value for active inflammation

Key Takeaways

• ESR is most useful when interpreted alongside clinical findings and other laboratory tests
• An unexplained increase in ESR is generally transitory and seldom due to serious disease 5
• ESR is particularly valuable in diagnosing temporal arteritis and monitoring treatment response
• Consider both ESR and CRP when evaluating inflammatory conditions for complementary information

Remember that while an elevated ESR indicates inflammation, it should prompt a targeted diagnostic approach rather than a non-specific battery of tests.