Paper I
Question
ESR
Answer
Erythrocyte Sedimentation Rate (ESR) is the rate at which red blood cells settle at the bottom of a vertical column of anticoagulated blood over a period of one hour, expressed in mm/hour.
Principle
- Governed by the balance between factors promoting red cell aggregation (rouleaux formation, driven by increased plasma fibrinogen and immunoglobulins) and factors resisting settling (red cell shape, number, surface charge/zeta potential)
Methods
- Westergren method: Standard/reference method, uses a longer column (200 mm)
- Wintrobe method: Uses a shorter tube (100 mm), less commonly used now
Normal values
- Men: up to 15 mm/hour (age-adjusted)
- Women: up to 20 mm/hour (age-adjusted)
- (General rule of thumb: age/2 for men, (age+10)/2 for women)
Clinical significance
- A non-specific marker of inflammation/tissue damage — elevated in infections, autoimmune disease, malignancy (especially multiple myeloma), and pregnancy
- Useful for monitoring disease activity in conditions like rheumatoid arthritis and polymyalgia rheumatica/giant cell arteritis
- Decreased in polycythaemia, sickle cell disease, spherocytosis, and severe leucocytosis