If a blood sample shows suspected platelet clumping on automated counting, which anticoagulant should be used when recollecting the sample?

If a blood sample shows suspected platelet clumping on automated counting, which anticoagulant should be used when recollecting the sample?

• A. EDTA
• B. Sodium citrate
• C. Heparin
• D. ACD

Answer: (B)

When automated platelet counting shows clumping, the issue is often EDTA-induced pseudothrombocytopenia, where antibodies cause platelets to agglutinate in an EDTA tube. Recollecting the sample in a different anticoagulant helps prevent this clumping and yields a more accurate count. Sodium citrate is the preferred choice because it preserves platelets in a dispersed state while still preventing clotting. Blood collected in citrate is typically kept at a 9:1 ratio of blood to citrate; because of this dilution, the citrate-derived platelet count should be corrected by multiplying by 1.1 to estimate the true whole-blood count. Other anticoagulants can be used in some contexts, but EDTA is the one most commonly associated with clumping, and ACD or heparin are not routinely used for standard platelet counting.

When automated platelet counting shows clumping, the issue is often EDTA-induced pseudothrombocytopenia, where antibodies cause platelets to agglutinate in an EDTA tube. Recollecting the sample in a different anticoagulant helps prevent this clumping and yields a more accurate count. Sodium citrate is the preferred choice because it preserves platelets in a dispersed state while still preventing clotting. Blood collected in citrate is typically kept at a 9:1 ratio of blood to citrate; because of this dilution, the citrate-derived platelet count should be corrected by multiplying by 1.1 to estimate the true whole-blood count.

Other anticoagulants can be used in some contexts, but EDTA is the one most commonly associated with clumping, and ACD or heparin are not routinely used for standard platelet counting.