FAQ

What are the differences between K2 and K3 EDTA tubes?
K2 EDTA (dipotassium) and K3 EDTA (tripotassium) tubes are both used as anticoagulants in blood collection, primarily differing in their chemical composition, form, and impact on blood samples. K2 EDTA is typically spray-dried on the tube wall, preferred for its stability, accuracy, and minimal effect on cell size, making it the standard for hematology tests like CBCs. Conversely, K3 EDTA is usually in liquid form, which can cause dilution and slight red blood cell shrinkage.  

Key differences between K2 and K3 EDTA tubes include:

• Chemical Composition: K2 EDTA contains two potassium ions, while K3 EDTA contains three.

• Physical Form: K2 EDTA is commonly supplied as a dry, spray-coated substance on the tube's interior, whereas K3 EDTA is often in a liquid form.

• Impact on Blood Cells: K2 EDTA preserves cellular morphology better, which is preferred for automated analyzers. K3 EDTA can cause red blood cell shrinkage, which can lead to a lower Mean Corpuscular Volume (MCV) and other parameter alterations, particularly at higher concentrations.

• Laboratory Recommendations: The International Council for Standardization in Hematology (ICSH) recommends K2-EDTA for its precision.

• Sample Dilution: Due to its liquid form, K3 EDTA can cause a slight dilution of the blood sample, which is not present with K2.