FAQ

Questions

1. I have read some old paper indicating that the 1 hour reading time of the ESR can be greatly reduced by the tube at an angle of 60 or 45 degrees instead of upright. Does this give accurate results?

2. Can I use EDTA anticoagulated blood to perform the ESR test?

3. When filling the Dispette 2 system, if the blood reaches the zero mark at the top before the other end of the Dispette gets to the bottom of the filling reservoir should I stop pushing and just set up the test in the stand as it is?

4. Can the Micro-Dispette give the same accuracy as the full Westergren method?

5. The Barrett & Hill paper (J. Clin. Path. 1980; 33 1118 - 1120) referred to in your literature indicates that the micro ESR equipment that you supply can be used for capillary blood samples as well as venous blood. We have found poor correlation between the two techniques - will you please comment?

6. Do Guest Scientific ESR systems conform to CLSI standards?

7. Anaemia: "I would like to know what effect Anaemia has on ESR results. I looked at the Clinical and Laboratory Standards Institute document. It does state that sedimentation is increased in Anaemia but that is about all it does say. Can you give me any further information?"

8. Strength of citrate: "The Dispette instructions call for a 3.3% (0.105M) buffered sodium citrate tube; however the black stoppered tubes for ESR determination on the Fisher catalogue are stated as containing 0.129M buffered sodium citrate for Westergren sedimentation rate determinations." Can I use the 0.129M citrate tube and what is the difference between the 0.105M and the 0.129M sodium citrate solutions?

9. Is the Dispette 2 ESR system self-zeroing or graduated?

10. What are the physical factors that affect the ESR?

11. I am told that the temperature at which the ESR test is done can vary the result. What other variables can influence results?

12. What are the normal values for ESR (Sed-Rate), do they differ between men, women and children?

13. How can we calibrate the Dispette systems?

14. What controls should be used for the Guest Sed Rate products?


1. I have read some old paper indicating that the 1 hour reading time of the ESR can be greatly reduced by the tube at an angle of 60 or 45 degrees instead of upright. Does this give accurate results?

No, the ESR tube (Dispette) must always be perfectly vertical as measured by a spirit bubble or plumb line. The papers in favour of the idea, written in the mid 1930's and early 1940's, were shown to be faulty by several workers and finally discredited in 1967 (Lemtis and Schoetensack). The International Committee for Standardisation in Haematology (ICSH) continues to recommend that, "the tube should be held vertical (confirmed by a plumb line or equally effective device)".


2. Can I use EDTA anticoagulated blood to perform the ESR test?

Yes, but if you are performing the Westergren method test as do most people today, you still need to make the one in five dilution (i.e. four parts blood added to one part diluent) that was used with the original technique because only liquid citrate was available at that time as an anticoagulant. The diluent you use can be normal saline or trisodium citrate at a concentration of between 0.10 to 0.136 mol/litre. - see ICSH recommendations, Journal of Clinical Pathology, 1993; 46: 198 - 203.


3. When filling the Dispette 2 system, if the blood reaches the zero mark at the top before the other end of the Dispette gets to the bottom of the filling reservoir should I stop pushing and just set up the test in the stand as it is?

No, because the red cells will fall into the space between the bottom of the Dispette and the filling reservoir and hence give inaccurate results. The Dispette must be pushed, firmly but gently, right to the bottom of the filling reservoir. The overflow chamber above the zero mark on the Dispette is designed to take the excess blood that will result from pushing right to the bottom.


4. Can the Micro-Dispette give the same accuracy as the full Westergren method?

No not all together, although some workers have shown good correlation between the two methods in samples with normal to slightly raised values (Barrett BA, Hill PI. J Clin Path, 1980; 33: 1118 - 1120). However, the higher the ESR the greater is likely to be the variation between the results given by the two methods. Never-the-less, this still means that the Micro-Dispette can be a very useful screening method or an indicator of normal or raised ESR values where it is difficult to obtain a larger volume of blood sample.


5. The Barrett & Hill paper (J. Clin. Path. 1980; 33 1118 - 1120) referred to in your literature indicates that the micro ESR equipment that you supply can be used for capillary blood samples as well as venous blood. We have found poor correlation between the two techniques - will you please comment?

We understand that Barrett & Hill suggested that the micro-method can be used with venous or capillary blood, however it is our experience that capillary blood samples will only give accurate results under the most strictly controlled conditions of sampling, i.e. a clean puncture over a maximum period of 30 seconds without excessive stasis. This is a situation that can be organized in a research laboratory with willing volunteers or in specialised paediatric units, but is unlikely to be practical in general hospitals, clinics or doctor's offices in an emergency situation or where an obdurate or distressed child is involved.


6. Do Guest Scientific ESR systems conform to CLSI standards?

Yes, those pipettes marked "Westergren" on the tube (i.e Dispette, Dispette 2, and Vacupette) are designed to meet the specifications (those of Westergren) set by the International Congress for Standardisation in Haematology (ICSH) published in 1993. The then NCCLS (now re-named the Clinical Laboratory Standards Institute or CLSI) standards were revised to conform to the ICSH Standards later that same year. The most recent review by the ICSH published in April 2011 confirms that the reference method for the measurement of ESR should be based on the Westergren method. The most recent publication from the CLSI, the US Approved standard 5th Edition, follows the same guidance. The 5 Place ESR stand is also designed to meet ICSH and CLSI recommendations.


7. Anaemia: "I would like to know what effect Anaemia has on ESR results. I looked at the Clinical and Laboratory Standards Institute document. It does state that sedimentation is increased in Anaemia but that is about all it does say. Can you give me any further information?"

Certainly both the ICSH and CLSI together with all the major textbooks confirm that anaemia will cause a raised ESR.

You will recall from our website section on the Physical Basis of Blood Sedimentation that the rate of fall of the red cells is influenced by a number of inter-reacting factors between the red cells and the plasma and can be roughly categorised into three phases of sedimentation. The rate is greatly influenced by the extent to which the red cells form rouleaux - the clumps of which sediment more rapidly than single erythrocytes.

Anaemia, by altering the ratio of red cells to plasma, encourages rouleaux formation and accelerates sedimentation in the lag phase. Cellular factors in anaemia may also affect the rate - e.g. in iron-deficiency anaemia, a reduction in the intrinsic ability of the red cells to sediment may compensate for the accelerating effect of an increased proportion of plasma. In addition, you may see a higher rate in blood loss anaemia due to the lower number of red cells available to crowd together in the packing phase.

Clinicians should be aware that anaemia affects the ESR and, as with all results, the ESR alone must not be taken as indicative of a particular disorder being present or absent.


8. Strength of citrate: "The Dispette instructions call for a 3.3% (0.105M) buffered sodium citrate tube; however the black stoppered tubes for ESR determination on the Fisher catalogue are stated as containing 0.129M buffered sodium citrate for Westergren sedimentation rate determinations." Can I use the 0.129M citrate tube and what is the difference between the 0.105M and the 0.129M sodium citrate solutions?

The ICSH recommends that the trisodium citrate should be "within the range 0.10 - 0.136 mol/L" as both the citrate concentrations you mention are within these limits - you can use either - the very slight difference in molarity, as far as the ESR is concerned, is negligible.


9. Is the Dispette 2 ESR system self-zeroing or graduated?

Dispette 2 is self-zeroing; that is to say, when you push the Dispette to the bottom of the reservoir any excess of blood sample is absorbed by the cotton plug in the overflow chamber at the top, formed by the two blue grommets. The grommet is like a one-way valve that lets the blood up but will not allow the red cells to fall back - thus the column of blood sample literally starts at the '0' mark which is set at the bottom of the lower grommet. Of course the Dispette is graduated as well; from 0 to 200 going downwards so that you can read the result easily. So it is not a question of either self-zeroing or graduated - it is both and neither property excludes the other.


10. What are the physical factors that affect the ESR?

Physical changes in both the plasma and the red cells can affect the ESR. Please go to the Technical Advice Section of this website for a more detailed explanation.


11. I am told that the temperature at which the ESR test is done can vary the result. What other variables can influence results?

The temperature at which the ESR test is performed is a vital factor influencing the result. However there are several other factors that can cause erroneous results. Please go to the Technical Advice section of this website, subsections Technical Variables and Technical Advice for Performing the test.


12. What are the normal values for ESR (Sed-Rate), do they differ between men, women and children?

This is a very commonly asked question to which there is no simple answer, please refer to the Normal Values section of this website.


13. How can we calibrate the Dispette systems?

All Guest Scientific equipment is read directly and visually from a scale that is printed on the side of the pipet during the manufacturing process.  This scale is graduated precisely to the Standard originally specified by Westergren as confirmed by the certificate of conformity for each product.  There is, therefore, no need for further calibration, neither is there any facility to do so. Please follow this link for further information.


14. What controls should be used for the Guest Sed Rate products?

The International Council for Standardisation in Haematology (ICSH) and the Clinical Laboratories Standards Institute both give guidance on controls for ESR tests. They recommend that laboratories instigate and record their own quality control system in accordance with ICSH or CLSI guidance and/or their own country’s regulatory requirements.

If this will prove difficult, or where no national guidance is provided, we suggest laboratories follow the practice that a number of our customers have successfully used; namely a product called Sedrite-Plus Hematology Controls. For full details please follow this link.