Why is there a false value change of platelet in routine blood test?

Routine blood testing is already a very important routine testing item. Platelet count is an important basis for the diagnosis and identification of hemostasis and thrombotic diseases. However, in daily testing, the platelet count using a blood cell counter may sometimes be falsely increased or Lower, why is this?

The role of platelets

Platelet is abbreviated as PLT, which belongs to blood cell like red blood cell and white blood cell. It is dimpled, oval or disk-shaped on both sides, but much smaller than red blood cell and white blood cell. The average diameter is only 2 to 4 microns. It is formed by fragments of bone marrow megakaryocyte cytoplasm shedding. . When blood vessels are damaged, platelets aggregate into clusters to form thrombus; and also release substances that promote vasoconstriction and blood clotting. Platelet count refers to the number of platelets contained in a unit volume of blood. Certain diseases can lead to a decrease or increase in the number of platelets.

Causes of false elevation of platelets

1. In some hemolytic diseases, hemolysis occurs in the blood vessels, and then the fragments generated by the rupture of red blood cells will be divided into the platelet area by the hemocytometer, which will cause errors in the instrument and falsely increase the count. For example, hemoglobinopathy and G-6-PD deficiency can cause intravascular hemolysis.

2. After the treatment of chronic granulocyte patients, a large number of fragments will appear in the blood vessels. These fragments will also be divided into the platelet area by the hemocytometer, which will cause interference and falsely increase the platelet count.

3. Take venous blood for routine blood testing within a short period of time after transfusion of fat emulsion, chylo particles will also be counted into platelets by the blood cell counter, resulting in high falsehood. All the above three types can be corrected by observing the morphology of platelets and red and white blood cells through artificial blood smears.

Causes of false reduction in platelets

1. EDTA-K2 anticoagulant causes platelet aggregation, which is related to the presence of cryptic antigens on the surface of platelets, causing the blood cell counter to treat the adhered platelets as non-platelets, resulting in a false decrease in counts. At this time, citrate can be used instead of EDTA-K2 as an anticoagulant, or platelets can be manually counted to correct.

2. Cold agglutinin can agglutinate red blood cells, nucleated cells, and platelets, thereby making the platelet count falsely lower. When encountering the interference of cold agglutinin in the body, the specimen can be incubated at 37 degrees for a period of time to eliminate the interference caused by cold agglutinin.

3. The invisible aggregation of platelets in hypercoagulable blood will make the count falsely lower. For example, hypermagnesium, hypercholesterolemia, and high triglycerides will all increase platelet aggregation.

The instrument used for blood cell analysis has the advantages of speed and simplicity, but it is also easy to cause errors. As an established blood test reagent company, Desheng recommends that when the platelet count does not match the clinical practice, it must be corrected by manual recheck to avoid unnecessary disputes between doctors and patients.