Inflammation parameters, inflammation value, acute phase protein, blood parameters in inflammation, blood value in inflammation
Blood cell sedimentation rate
The measurement of the blood sedimentation rate (BSG), also known as blood sedimentation reaction or erythrocyte sedimentation rate (ESR), is a quite old, but still relevant method for determining the general inflammatory state of a person. According to the method developed in 1921, 1.6 ml of patient blood is mixed with 0.4 ml of 3.8% sodium citrate solution to prevent clotting of the blood. This mixture is drawn up in a very thin glass tube of 20 cm length and left standing vertically.
Gravity causes the red blood cells (erythrocytes) contained in the blood to sink slowly to the bottom, and in the upper part of the tube an almost cell-free area is formed that can be clearly defined with the naked eye. The height of this area (measured in mm) is read off after one hour (or after 2 or even 24 hours in certain cases). During an inflammation, the red blood cells tend to cluster together due to the blood changes that accompany it and then sink to the ground faster because of the now lower flow resistance.
An evaluation of the SPA is problematic for several reasons. There are very many factors that influence the SPA. For example, a reduced number of blood cells (hematocrit), various drugs (such as steroids), age, pregnancy, increased fibrinogen, as well as immunoglobulins and acute-phase proteins lead to an increased SPA, while a lot of albumin (the most common blood protein), contrast media containing iodine, a lot of endurance sports and deformed or differently sized red blood cells lead to a lower SPA.
The fact that there are so many influencing factors means that an elevated ESRD can be caused by a variety of diseases (autoimmune diseases, infections, cancer) or other circumstances, and also means that a normal ESRD does not always rule them out. Furthermore, the stated limit values sometimes vary considerably depending on the source. Researchers also describe a wealth of possibilities, e.g. due to different temperatures or errors in the volume measurement of blood and sodium citrate, to obtain different SPA values with the same patient blood.
After an infection it takes about 4 weeks until the BSG returns to normal. In most cases, the upper limit of the SPA after one hour of sedimentation is 15mm for men and 20mm for women under 50 years of age, and 20mm and 30mm for those over 50 years of age. An assessment of an ESR value should always be made only in a clinical context and preferably in combination with other inflammation parameters.
