The Kotov–Kotovshchikov thrombothrombostatic test (KTT) is a screening non-invasive study of platelet function that allows one to assess the risk of thrombotic complications in acquired or hereditary forms of hemostasis pathology. The main diagnostic criterion in this case is a decrease in the sensitivity of platelets to arachidonic acid and an increase in their aggregation with inducers. The test has been used in clinical practice for more than 60 years and continues to be very popular due to the ease of its implementation, non-invasiveness and informativeness of the result obtained. When performing the test, the determination of spontaneous platelet aggregation is used, followed by induction with arachidonic acid, adrenaline or adrenaline ether alcohol. High reliability of the results is achieved by repeating the analysis with 2-3 hour breaks. Indications for CTT: * differential diagnosis of dysfunction of platelet hemostasis; * examination of patients with symptoms of vascular-platelet disorders or suspicion of them based on clinical and laboratory data * period of initial examination before surgical interventions, especially with the implantation of prostheses and the introduction of intravenous catheters; with atherosclerosis