Platelets are small non-nuclear shaped blood cells. They participate in hemostasis (a complex of reactions aimed at stopping and preventing bleeding). Platelets are round or oval. The diameter of the cells is from two to four microns.
In blood vessels, platelets are located near the walls or in the bloodstream. In the second case, the cells are in a calm state and have the form of a disk. Platelet activation contributes to a change in their shape: the cells become spherical and form special outgrowths (pseudopodia). With the help of these processes, blood elements are able to adhere to each other or to the wall of a vessel that has damage. This phenomenon is called aggregation. Platelets, in addition, have the properties of adhesion (adhesion), degranulation (release of contents), clot retraction (complete separation or reduction of a blood clot from serum). On their surface, these cells are able to transfer fibrinogen, biologically active substances (serotonin), anticoagulants, as well as immune complexes (circulating).
By means of platelet adhesion and aggregation , hemostasis is achieved in small-caliber vessels (cells accumulate in the area of damage). Adrenaline, thrombin, collagen, and serotonin act as stimulants of the adhesion process. With the participation of thrombin, the formation of processes (pseudopodia) occurs. Platelet granules contain coagulation factors (serotonin, peroxidase enzyme, platelet fibrinogen, adenosine diphosphate (ADP), serotonin, platelet growth factor, von Willebrand factor).
In the process of blood clot retraction, adhesion to the fibrin filaments and the release of thrombostenin, which settles on them, occurs. As a result, compaction and twisting of the threads occurs, thus, the primary thrombus is formed.
A platelet blood test allows you to determine coagulation. A concentration of 180-320 thousand per milliliter is considered normal.
If the platelets are elevated, then thrombocytosis occurs. Such a condition may indicate a chronic disease of an infectious nature, a tumor, a blood disease. Thrombocytosis can cause blood clots in blood vessels. If the platelets are elevated, then the body may be dehydrated. This condition can be triggered by vomiting, insufficient fluid intake, and upset stool.
The platelet concentration in the blood may vary depending on the time of year or day. A decrease in cell content can occur during the menstrual period or during pregnancy. Platelets are often elevated after physical exertion.
Thrombocytosis can occur in both adults and children. An increase in platelet concentration may be primary or secondary.
In children, thrombocytosis is established after the exclusion of congenital pathologies.
Platelets are primarily elevated, usually with erythremia, chronic myelogenous leukemia, and other blood diseases. An increase in the concentration of blood bodies is associated with an acceleration of the division of their predecessor (megakaryocytes). This process is characteristic of tumor transformation.
Secondary thrombocytosis is detected in diseases that arise on the basis of increased production of thrombopoietin (a polypeptide hormone).
Platelets can be elevated with ulcerative colitis, pulmonary tuberculosis, articular lesions of a rheumatoid nature, extrapulmonary tuberculosis, amyloidosis, osteomyelitis, cirrhosis of the liver and other chronic inflammatory pathologies. Thrombocytosis occurs against the background of the development of malignant neoplasms, bleeding, after certain birth injuries.