Platelet agglutination test

Platelets play a very important role in many body processes such as blood clotting, blood clot formation, vasoconstriction and repair as well as immunity, inflammation, atherosclerosis. In which the blood clotting process is of great interest in clinical practice and the platelet aggregation test will help evaluate this function of the platelet cells in the patient's body.

In blood samples collected from patients, after giving stimulants (ADP, collagen,...) platelets will be activated and irreversibly aggregate, changing optical density or resistance of currents. electricity, from which scattered light can be used to investigate this condensation process. This test is indicated only in bleeding patients with a normal platelet count.

After the patient is taken with fasting blood, whole blood will be used directly for testing or injected with 3.8% sodium citrate anticoagulant and centrifuged to collect platelet-poor plasma for testing. The platelet aggregation will then be measured through the following steps:
Prepare the following platelet condenser for 10 min, aspirate each 500 μl cuvette (platelet-rich cuvette with magnetic stirrer), incubate freeze in the incubation well of the machine for 5 minutes. Start platelet aggregation support software Add reagent to the condenser cuvette with collagen (1 μl) and the condenser cuvette with ADP (5 μl) Observe the graph to saturation and wait for the computer to calculate the results get

The results of platelet aggregation are expressed in terms of maximum aggregation, the slope of the aggregation curve, and the time from onset of aggregation to maximal aggregation where maximal aggregation is commonly used. especially:
normal ADP: 59-88% Normal collagen: 58-78% Platelet aggregation will tend to decrease in congenital or acquired platelet dysfunction or increase in cases of increased platelet function. platelet activation (pregnancy, surgery or certain cardiovascular conditions)

When conducting the technique of measuring platelet aggregation, it is necessary to pay attention to the following points:
For the case of using an aggregation meter by the principle of optical density change, the patient needs to fast for 12 hours before blood collection The results of platelet aggregation in platelet-rich plasma samples with platelet counts below 200.10^9/l or more than 400.10^9/l are generally of little value in assessing platelet quality. In the case of using whole blood to measure platelet aggregation, the results can be influenced by many factors, especially hematocrit. department.