Erythrocyte Sedimentation Rate (ESR)
Erythrocyte Sedimentation Rate (ESR)
Key Points
- Non-specific marker of inflammation and infection
- Measures rate of red blood cell sedimentation in plasma
- Valuable in diagnosis and monitoring of inflammatory conditions
- Results affected by multiple physiologic and pathologic factors
- Particularly useful in pediatric rheumatology
Basic Science
The ESR test measures the distance erythrocytes fall under gravity in anticoagulated blood during one hour. The rate is influenced by:
- Plasma proteins (especially fibrinogen and immunoglobulins)
- Red blood cell size, shape, and number
- Plasma viscosity
- Temperature and time of testing
Testing Methods
Traditional Westergren Method
- Sample Collection:
- EDTA or sodium citrate anticoagulated blood
- Strict temperature control (18-25°C)
- Testing within 4 hours of collection
- Vertical alignment critical
- Procedure Steps:
- Fill Westergren tube to 200mm mark
- Place in rack at precise 90° angle
- Read after exactly 60 minutes
- Record distance in millimeters
Modified Methods
- Automated Systems:
- TEST 1 analyzer
- Alifax Test 1 THL
- Microsedimentation methods
- Photometric rheoscopy
- Quality Control:
- Daily calibration checks
- Temperature monitoring
- Time standardization
- Regular maintenance protocols
Primary Clinical Indications
Inflammatory Conditions
- Rheumatologic Disorders:
- Juvenile Idiopathic Arthritis
- Systemic Lupus Erythematosus
- Kawasaki Disease
- Henoch-Schönlein Purpura
- Inflammatory Bowel Disease
- Infectious Diseases:
- Osteomyelitis
- Septic Arthritis
- Endocarditis
- Tuberculosis
- Deep-seated infections
Malignancy Screening
- Lymphoma
- Neuroblastoma
- Bone malignancies
- Metastatic disease
Reference Ranges
Age-Specific Normal Values
- Newborns: 0-2 mm/hr
- Neonates to puberty:
- Male: 1-11 mm/hr
- Female: 1-13 mm/hr
- Adolescents:
- Male: 3-13 mm/hr
- Female: 3-15 mm/hr
Clinical Significance of Elevated Values
- Mild Elevation (20-30 mm/hr):
- Mild inflammation
- Local infections
- Early disease stage
- Moderate Elevation (30-70 mm/hr):
- Active inflammatory disease
- Significant infection
- Autoimmune conditions
- Marked Elevation (>70 mm/hr):
- Severe systemic disease
- Malignancy
- Major infection
Pediatric-Specific Factors
- Neonatal Period:
- Lower baseline values
- Limited diagnostic utility
- High false-negative rate
- Infancy and Early Childhood:
- Greater variability in normal range
- Impact of recent vaccinations
- Effect of concurrent viral infections
- Adolescence:
- Gender differences emerge
- Hormonal influences
- Growth-related variations
Monitoring Disease Activity
- Serial Measurements:
- Baseline documentation
- Treatment response assessment
- Disease progression monitoring
- Relapse detection
- Integration with Other Tests:
- C-reactive protein (CRP)
- Complete blood count (CBC)
- Clinical assessment scores
- Imaging findings
Treatment Response Assessment
- Expected Patterns:
- Gradual decrease with effective treatment
- Persistence suggests ongoing inflammation
- Sudden increase may indicate complication
Technical Limitations
- Pre-analytical Variables:
- Sample handling time
- Temperature variations
- Tube position
- Anticoagulant effects
- Interfering Factors:
- Anemia or polycythemia
- Abnormal protein levels
- Medication effects
- Recent meal
Clinical Limitations
- Low Specificity:
- Multiple causes of elevation
- Poor disease differentiation
- Influenced by non-pathologic factors
- Monitoring Challenges:
- Delayed response to changes
- Variable normalization time
- Poor correlation with disease severity
