Pseudothrombocytopenia

Pseudothrombocytopenia or platelet clumping is a laboratory artifact where platelets adhere to one another in the blood sample, leading to a falsely low platelet count when analyzed by an automated machine. This phenomenon is usually caused by the anticoagulant ethylenediaminetetraacetic acid (EDTA) used in blood collection tubes.

Causes

The primary cause of pseudothrombocytopenia is the reaction between platelets and EDTA, an anticoagulant used in blood collection tubes. EDTA chelates calcium ions, which are necessary for platelet aggregation. In some individuals, this can lead to the formation of platelet aggregates, which are not counted as individual platelets by automated machines, leading to a falsely low platelet count.

Diagnosis

Pseudothrombocytopenia is typically diagnosed when a patient has a low platelet count on an automated blood count, but no symptoms of thrombocytopenia. The diagnosis can be confirmed by examining a blood smear under a microscope, where the platelet clumps can be seen. Alternatively, a blood sample can be drawn into a tube with a different anticoagulant, such as citrate or heparin, which does not cause platelet clumping.

Treatment

No treatment is necessary for pseudothrombocytopenia, as it is not a true platelet disorder but a laboratory artifact. However, it is important to recognize the condition to avoid unnecessary testing or treatment for thrombocytopenia.

See also

• Thrombocytopenia
• Platelet
• Complete blood count