Everyone should be familiar with blood routine examination, after all, anyone who has medical experience in a hospital must have received a blood injection to some extent. But there is something called ethylenediaminetetraacetic acid salt (EDTA) that many people may not understand. What is this difficult to read thing? In fact, EDTA is the most commonly used anticoagulant in current blood routine tests, which can bind with calcium ions in the blood to form stable complexes, thereby preventing blood clotting and exerting anticoagulant effects. However, EDTA also has certain drawbacks. EDTA can cause EDTA dependent pseudothrombocytopenia. Below, we will take you to understand this special situation and how to avoid pitfalls.
1、 What is EDTA dependent pseudothrombocytopenia? EDTA is widely used as an anticoagulant because it can maintain the volume and morphology of red blood cells, white blood cells, and platelets unchanged, making it an ideal anticoagulant. However, in some cases, EDTA may occasionally induce platelet aggregation, accumulation, and satellite phenomena, leading to inaccurate identification by blood analyzers and significantly lower values than the true values measured by the instrument. This is called EDTA dependent thrombocytopenia, also known as EDTA dependent thrombocytopenia (PTCP). The incidence of PTCP in clinical practice is actually not high, about 0.09% -0.21%. In addition, this situation is much higher in hospitalized patients, and relatively speaking, the incidence of emergency and outpatient treatment is slightly lower. In clinical practice, many diseases have the potential to cause thrombocytopenia, with hematological, digestive, and rheumatic immune system diseases being the most common. So when a patient's blood routine test shows thrombocytopenia, although it is not consistent with their clinical symptoms, clinical doctors often become fixated on the cause and may unnecessarily add many auxiliary tests to the patient without reason, resulting in a certain degree of waste of medical resources. Serious cases may even lead to clinical misdiagnosis, mistreatment, and medical disputes.
2、 Why does EDTA dependent pseudothrombocytopenia occur? Although the mechanism of PTCP is not yet clear, the widely accepted theory is that due to the use of EDTA anticoagulants, certain antibodies in the immune-mediated blood cause platelet aggregation. This antibody directly acts on platelet membrane glycoproteins IIb/IIIa, as GPIIb/IIIa is a positive subset of the integrin family, located on platelets and macrophages, and serves as a receptor for ligands of macromolecules such as fibrinogen and Vanwillebrand. Its main function is to mediate platelet aggregation. In addition, white blood cells and platelets can also interact with each other through adhesion protein molecules. Studies have shown that quiescent platelets cannot react with monocytes or neutrophils, but platelets activated by thrombin react with monocytes and neutrophils in a calcium dependent manner. Because both white blood cells and activated platelets have TSP receptors on their surfaces, pseudo thrombocytopenia occurs under a blood analyzer.
3、 How to avoid the adverse effects of EDTA dependent pseudothrombocytopenia
In normal testing work, when using a blood analyzer to count EDTA anticoagulated specimens, special attention should be paid to the occurrence of thrombocytopenia, especially for individual thrombocytopenia. Firstly, the testing personnel must carefully observe and check the status of the specimens, instruments, and reagents. Secondly, the testing personnel must communicate with the patient or the corresponding clinical doctor, inquire about the patient's physical signs, especially pay attention to whether the patient has bruising, bleeding points, and thrombolytic drug treatment. Then, if there is an abnormal situation of thrombocytopenia, the testing personnel must conduct retesting and immediately perform retesting (peripheral blood cell morphology analysis). Finally, if necessary, it is necessary to replace the anticoagulant or testing method.
In summary, if inspectors discover a decrease in platelet count results, it should be given sufficient attention and comprehensive measures should be taken for re examination to avoid issuing incorrect test results, reduce medical disputes, and build a harmonious doctor-patient relationship.