Posted by jayaram in Introduction
Normally, the red blood cells remain suspended uniformly in circulation. This is called suspension stability of red blood cells. If blood is mixed with an anticoagulant and allowed to stand on a vertical tube, the red cells settle down due to gravity with a supernatant layer of clear plasma. The rate at which the cells settle down is called Erythrocyte Sedimentation Rate.
Determination of Erythrocyte Sedimentation Rate
There are two methods to determine Erythrocyte Sedimentation Rate.
By Westergren’s method
Westergren’s tube is 300m long and opened on both ends. 1.6ml of blood is mixed with 0.4ml of 3.8 percent sodium citrate anticoagulant and loaded in the Westergren’s tube. The tube is fitted to the stand vertically and left undisturbed. The reading is taken at the end of 1 hour.
By Wintrobe’s method
Wintrobe’s tube is a short tube (110 mm long) with opening on only one end. About one ml of blood is mixed with the anticoagulant, EDTA. The blood is loaded in the tube up to 0 mark and the tube is placed on the wintrobe’s stand. And, the reading is taken after one hour. Wintrobe’s tube is also used for determining Packed Cell Volume.
Normal value of Erythrocyte Sedimentation Rate
By Westergren’s method
In males 3 to 7mm in one hour
In females 5 to 9 mm in one hour