Esr method, principle and interpretation

ERYTHROCYTE SEDIMENTATION RATE: METHOD, PRINCIPLE AND INTERPRETATION.

1. ESR – PRINCIPLE, METHODS AND INTERPRETATION

2. DEFINITION The rate at which erythrocytes settle down at bottom of the tube at 1 st one hour is regarded as Erythrocyte Sedimentation Rate. ESR is a commonly used nonspecific test in routine clinical practice.

3. CHARACTERISTICS Indicative of inflammation. Used as initial screening tool. Follow up test to monitor therapy and progression/remission of disease. Easy to perform. Inexpensive. Unit – measured in mm/hr.

4. CLINICAL SIGNIFICANCE OF ESR To follow the course of disease. To establish the prognosis in certain chronic disease. To support the diagnosis.

5. ZETA POTENTIAL Measure of magnitude of electrostatic charge or repulsion/attraction between particles. Zeta potential results from negatively charged sialic acid groups on RBC’s membrane.

6. MECHANISM

7. STAGES OF ERYTHROCYTE SEDIMENTATION

8. FACTORS THAT INCREASE ESR

9. FACTORS THAT DECREASE ESR

10. METHODS

11. WESTERGREN METHOD International reference method. REQUIREMENTS: 1. Westergren ESR pipette- Straight glass pipette. 300 mm in length. 0-200 marking from top to bottom- only in lower 2/3 rd of tube. Diameter 2.55mm.

12. 2. Westergren stand- holds tube in vertical, motionless position. 3. Anticoagulant - Trisodium Citrate Dihydrate is anticoagulant of choice. Composition – Trisodium Citrate Dihydrate- 32 gm Distilled water – 1000 ml

13. PROCEDURE

14. MODIFIED WESTERGREN METHOD Only modification-It uses EDTA as anticoagulant rather than with citrate. 2ml of well mixed EDTA blood is diluted with 0.5ml of 3.8% sodium citrate or 0.85% of sodium chloride.

15. REFERENCE RANGE Reference range- MEN WOMEN Below 50 years of age 0-15mm/ hour 0-20mm/ hour Above 50 years of age 0-20mm/ hour 0-30mm/ hour Above 85 years of age 0-30mm/ hour 0-42mm/ hour Newborns 0-2mm/ hour Children to puberty 0-13mm/ hour Henry’s clinical diagnosis and management by laboratory methods

16. PRECAUTIONS Wash the pipette as early as possible. Rinse in deionized water and dry in incubator between 40-50℃.

17. WINTROBE’S METHOD It can be used for both ESR and PCV. REQUIREMENTS : Wintrobe’s tube: 110 mm in length. 3 mm in diameter. Two markings: 1 st marking for ESR (above downwards), 2 nd marking for PCV (below upwards).

18. Vertical stand : holds tube in vertical and motionless position. Anticoagulant : EDTA or Double oxalate. Pasteur pipette: To fill Wintrobe tube (2ml syringe with needle can also be used).

19. PROCEDURE

20. Reference range RANGE Males 0-9mm/ hour Females 0-20mm/ hour Children 0-13mm/ hour

21. PRECAUTIONS Wash the tubes under running tap water by introducing a thick wire in tube repeatedly to remove packed cells completely. Dry tubes in incubator (40-60 C). In case of infants or insufficient blood quantity use Micro-Sedimentation (Landau) method.

22. Micro –ESR method Landau-Adams micro sedimentation method. REQUIREMENTS : Fasting capillary blood (finger tip, heel or toe). 5.0 g/dl sodium citrate solution. Landau pipette graduated from 0-50mm (resembles RBC pipette). Landau pipette stand. Suction device.

23. PROCEDURE

24. Normal values: RANGE Males 0-5mm/ hour Females 0-8mm/ hour Newborn 0-2mm/ hour

25. Corrected ESR To eliminate the influence of anemia on ESR. Corrected according to the volume of Red cells. For correction we use Fabry’s formula. Fabry’s formula: Corrected ESR = Measured ESR x 15/ (55-Hct)

26. Automated methods Ves-matic 20 ESR-Stat plus Sedi -mat 15

27. VES-MATIC 20

28. VES-MATIC 20 Opto electrical sensor measure ESR.

29. ESR STAT-PLUS It is a Centrifugation based method . Provides results in 5 minutes. Sample is placed in centrifuge. Infrared laser tracks the erythrocyte plasma interface and takes multiple measurements. Linear portion of sedimentation is identified. Software algorithm to determine ESR result.

30. SEDI-MAT 15 Filled sedimat Westergren pipette is placed in SEDIMAT 15 which accelerates sedimentation under controlled condition. Based on the ability of blood to block the transmission of infra red rays. The reader displays result on LCD screen after 15 minutes.

31. ZETA SEDIMENTATION RATE More accurate data than ESR. Not affected by anemia . Small amount of blood for testing. Provides fastest result. Requires a Zetafuge . Four 45 second cycles of dispersion and compaction in capillary tubes.

32. PROCEDURE

33. Values of ZSR Normal: 51-54% Mildly elevated: 55-59% Moderately elevated: 60-64% Markedly elevated: >64%

34. ADVANTAGES OF AUTOMATED METHODS Save technician time. Requires small sample volume. Generate more rapid results.

35. SOURCES OF ERROR Haemolysed blood sample. Clotted blood. Presence of air bubble. Er r or du e t o su n l i ght, vibration, s m al l bor e s i ze, dirty and wet tube. Delay or wrong method in performing the test.

36. INTERPRETATION In conclusion, conditions with very high ESR (more than 100mm/ hour) are: Multiple myeloma Connective tissue disorders - SLE, RA and other autoimmune diseases Tuberculosis Temporal arteritis Severe anemia Malignancies * ESR has little diagnostic value in these disorders but can be useful in monitoring disease activity.

37. INTERPRETATION Conditions with low ESR: Polycythemia Severe Leukocytosis Sickle cell anemia Hereditary spherocytosis Hypofibrinogenemia Low plasma protein due to liver or kidney disease.

38. LIMITATIONS OF ESR ESR is a non specific phenomenon and reflects only change in plasma protein pattern and the variation in RBC volume. Cannot be used as a diagnostic tool. Does not indicate the nature of the disease.