ESR (Westergren method)

Principle

• Anticoagulated blood stands in a vertical tube; red cells settle and the plasma column cleared in 1 hour is measured.
• Settling mainly depends on rouleaux formation, which is promoted by raised fibrinogen and globulins (acute phase and paraproteins).

Specimen

• 4 volumes blood + 1 volume 3.2% (0.109 M) trisodium citrate; or EDTA blood diluted 4:1 with citrate or saline per ICSH.
• Test within 4 h at room temperature (EDTA blood can be held up to about 24 h at 4 °C, then brought to room temperature).

Reagents and equipment

• Westergren tube with 200 mm scale, internal diameter at least 2.55 mm; rack holding tubes exactly vertical.

Procedure

• Mix sample well, fill the tube to the 0 mark without bubbles.
• Place vertically in the rack at 18–25 °C, away from vibration, draughts and direct sunlight.
• Read the distance from the top of the plasma to the top of the red cell column after exactly 60 min; report in mm/h.

Normal values

• Typical adults: men up to about 10–15 mm/h, women up to about 20 mm/h; rises with age (rough guide: men age/2, women (age + 10)/2). Local ranges apply.

Quality control and pitfalls

• Falsely high: tilted tube, high room temperature, anaemia, over-dilution with anticoagulant.
• Falsely low: clotted sample, delay in testing, low temperature, polycythaemia, sickle cells, spherocytes, acanthocytes, high WBC count.
• Increased physiologically in pregnancy and old age.

Clinical use

• Non-specific marker of inflammation; used in monitoring temporal arteritis, polymyalgia rheumatica, TB and myeloma.
• Very high values (over 100 mm/h) suggest myeloma, severe infection, malignancy or connective tissue disease.