PURPOSE OF EXAMINATION:

ESR is a useful screening test in a routine examination of any patient. It is a useful marker for underlying inflammation.

PRINCIPLE OF ESR :

When well mixed venous blood is placed in a vertical tubes Erythrocytes tend to fall towards the bottom.The length of fall of the top of the column of Erythrocytes in a given interval of time is termed as ESR.

PRINCIPLE OF INSTRUMENT:

The Precil LBY – XC20B ESR Analyser is an automatic instrument controlled by a microprocessor and exclusively employed for the analysis of the ESR. It constantly and simultaneously scan 20 test tubes, which are custom made for ESR Analysis. Precil LBY – XC20B follows the sediment of the each sample independently, memorizing levels for the whole period of analysis.

PERFORMANCE SPECIFICATION:

A. Mechanical/ Optical precision of detection: +/- 5 %

B. Repeatability error: less than 3%

C. Temperature precision : +/- 0.5 ^.C

Temperature stability : +/- 0.2 ^.C

D. Identify of different cannels : 5%

E. Measuring range : 1-140 mm/hr

SAMPLE TYPE REQUIRED : Well mixed EDTA whole blood

ADDITIVE : Sodium Citrate (3.8 %)

CALIBRATION REQUIRED: Calibration done by manufacturer annually and calibration certificate is received

DETAILED WORK BENCH PROCEDURE :

Sample Preparation:

• ESR – vacuum blood collection tube contains 3.8% Sodium Citrate & vaccum to draw 1.28ml of blood.
• Write down patient’s lab no. on label before sample collection

Procedure:

• Switch on the Analyzer unit.
  • Working time -30 min and temperature correction to 27’C is already set.
  • Machine will display “TEST” menu automatically. If not then manually enter main menu to move cursor to “TEST” & press “OK” to enter this menu.
  • On the screen, test tube positioning plate is highlighted in which actual positions of test tubes are described as below:

e_ : This channel has no tube.

ESR : Sedimentation tube is inserted and waiting for test.

E2 : This channel is performing sedimentation testing, digit stand for scanning testing.

… : This channel is scanning testing.

h : This channel is waiting for inserting tube.

Hct : This channel is performing hematocrit testing.

8 : Sedimentation value of this channel is 8 mm/hr.

H48: Erythrocyte hematocrit is 48%

• Take a ESR – vacuum blood collection tube and fill blood sample upto mark and mix it well.
• Introduce tube into reading channel. ESR indicator will appear on screen at respective ESR tube position.
• Enter the patient ID/lab no. into register according to sample position.
• Read the result after 30 minutes and mention it into register according to sample position.
• Remove the tube and discard it.

• Swith off the analyser unit.

QUALITY CONTROL PROCEDURE :

• Daily one random patient sample is checked by manual method (Modified Westergrene) and automated method. Results of comparison are recorded in HI: C\records\file\9\Internal quality control records.
• Daily one random patient sample is run in the morning and same sample is run in evening on Automated ESR analyzer. Results of comparison are recorded in HI:C\records\file\9\Internal quality control records.

• Monthly one sample is sent for interlaboratory comparision and records of which are filed in C:/ Recoreds/ File2/ Result of EQA and interlaboratory comparision

INTERFERENCE :

• High Concentratoin of Anticoagulant may alter the value of ESR.
• Heparin if used as Anticoagulant alters membrane Zeta potential may affect ESR.
• Bubbles left in the tube may alter ESR.
• Hemolysis may alter ESR.
• Tilting of tube accelerates ESR.
• Temperature should be within 10’-30’C
• Time – Do the ESR within 6 Hrs of collection, if sample is stored at 4degree celcius, processing can be done up to 24 hours. On standing, erythrocytes become spherical and so less rapidly form roulex. So, ESR is falsely low.

BIOLOGICAL REFERENCE INTERVAL :

REPORTABLE INTERVAL FOR EXAMINATION RESULT : 1-140 mm/hr

CRITICAL VALUE :

Stroke> 28

Prostatic cancer> 37

CAD>22

Metastasis >100

Temporal arteritis>90

INTERPRETATION BY THE LABORATORY :

Markedly increase in Multiple Myeloma, hyperfibrinogenemia

Moderately increase in Acute Inflammatory disease, Rhumatoid Arthritis, chronic infections, tuberculosis, collagen disease

ESR is useful to check the progress of disease, if the patient is improving ESR tends to fall, if the patient condition is getting worse, the ESR tends to rise.

POTENTIAL SOURCE OF VARIABILITY :

Preanalytical sources of variability**: Delayed sample receipt, Leucocytosis, Leukemia, Septicemia, short draw in vacuum tube.

1.Difference in specific gravity between red cells and plasma.

2.Extent to which red cells form rouleaux ,which sediment more rapidly than single cells.

3.Ratio of red cells/plasma(PCV).

4.Plasma viscosity.

5. The dilution (if any) of the blood.