Three types of anticoagulants commonly used for blood collection: dipotassium ethylenediaminetetraacetate (K2EDTA), sodium citrate and heparin.
Dipotassium EDTA is the anticoagulant of choice for blood counting and sizing because it produces less shrinkage of RBCs and less increase in cell volume on standing.
Three forms of EDTA are available, and ssed in 1.5 mg/mL of whole blood.
EDTA mode of action is that it removes ionized calcium by chelation.
Excessive EDTA produces shrinkage of red blood cells and can alter the hematocrit level.
EDTA produces and insoluble calcium salt that prevents blood coagulation.
EDTA is the most commonly used anticoagulant in hematology lab testing for complete blood count and any of its components.
Sodium citrate removes calcium from the coagulation system precipitating it into an unusable form.
Sodium citrate is a mild calcium chelator.
Sodium citrate used in a 3.2% solution with a 1:9 ratio to whole blood.
Sodium citrate in excess can cause abnormal PT and aPTT results.
Sodium citrate is used as an anticoagulant for PT, aPTT and sedimentation rate studies.
Heparin is used in blood collection specimens by inhibiting thrombin and factor Xa.