Aim: To measure the erythrocyte sedimentation rate of a patient to see if there could be anything wrong.
The erythrocyte sedimentation rate (ESR) is the distance that the red blood cells sediment in a specific time interval. ESR is an easy, inexpensive and non-specific test that is used to help protect conditions associated with acute and chronic inflammation including infections, cancers and autoimmune diseases. ESR is said to be non-specific because increased results do not tell the doctor exactly where the inflammation is in the body or what the cause of it is. Also, the readings can be affected by other factors besides inflammation so therefore ESR is mainly used in conjunction with other tests. However, an advanced rate does not diagnose a specific disease, but it does indicate that an underlying disease may be present. (1)
ESR takes place in the following 3 steps: the rouleaux formation which the sedimentation rate is slight (the lag phase which reflects red cells rouleaux formation);sinking of rouleaux at constant speed which is when sedimentation occurs at a fairly rapid rate (decantation phase in which the plasma-red cell interface falls more rapidly); and the last step where the rouleaux packs at the bottom of the tube with reduced rate in which the sedimentation rate is slow because of the accumulation of RBC’s in the bottom of the tube .(3)
The ESR increases as a disease worsens and decreases when the disease improves. ESR is called an acute-phase reactant test, meaning that it reacts to acute conditions in the body such as infections or trauma. The rate increase follows a rise in temperature and white blood cells count, peaks after several days and usually lasts longer than the elevated temperature or white blood cell count.(2)
In this experiment, the Wintrobe method will be used. EDTA anti-coagulated blood without extra diluents will be drawn into a tube in a vertical position. The
References: 1. Lab test online, 2010.erythrocyte sedimentation rate/online] (updated July 11, 2011). Available at www.labtestonline.org/esr/html. [Accessed on 4 September 2012] 2. The McGill Physiology Virtual Lab, 2011, erythrocyte sedimentation rate(ESR)/Online] Available at http://www.medicine.mchill.ca/physio/vlab/bloodlab/ESR.htm. [Accessed on 4 September 2012] 3. Kopke,A.2012. Haematology practical manual. MIDRAND GRADUATE INSTITUTE.