A significant part of hematological pathologies is associated with impaired functioning of the bone marrow. Often these disorders are accompanied by an increase in the number of cells produced. This pathological condition is called polycythemia. Polycythemia is a serious pathology that has dangerous complications. Consider the main causes leading to polycythemia, as well as types of polycythemia.
What is polycythemia? The incidence of chronic leukemia & nbsp; their complications
Polycythemia has several names – Wakez disease, erythremia, erythrocytosis, and belongs to the group of chronic leukemias. Pathology is manifested by an increase in the number of red blood cells in the blood, a significant increase in the level of hemoglobin and the total volume of red blood cells. Polycythemia is a rare form of leukemia. The prevalence of the disease – 4-5 cases of this form of chronic leukemia are diagnosed annually per 1 million people.
Polycythemia most often develops after the age of 50 and is a serious pathology that can provoke thrombotic and hemorrhagic complications, as well as transform into chronic myelosis, erythromyelosis and acute myeloid leukemia.
As a rule, polycythemia is an actual problem in older people.
What processes lead to the development of polycythemia?
Polycythemia develops under the influence of mutations in pluripotent stem cells, from which all hematopoietic sprouts are formed. The JAK2 tyrosine kinase gene is often mutated, in which valine is replaced by phenylalanine at position 617. Polycythemia is characterized by the presence of two types of precursor cells of erythroid hematopoiesis. The division of some cells is not regulated by erythropoietin, they behave autonomously, while other cells are erythropoietin-dependent and are the main substrate of polycythemia.
With the development of polycythemia, an increase in erythropoiesis is characteristic, resulting in absolute erythrocytosis. Against the background of such changes, blood clotting is disturbed and its rheological properties worsen, myeloid metaplasia of the liver and spleen develops.
Increased blood viscosity provokes the formation of thrombosis, which contributes to hypoxic tissue damage.
Ultimately, polycythemia leads to hematopoietic depletion and myelofibrosis.
Classification of polycythemia. Manifestations of primary and secondary polycythemia
Polycythemia can be true and relative. Relative polycythemia is considered with a normal number of erythrocytes in the blood, but subject to a decrease in the volume of the plasma. This condition is called stress or false polycythemia and is not considered as a pathological process of chronic leukemia. Polycythemia vera can be primary or secondary.
Causes and manifestations of types of polycythemia:
- Primary polycythemia is an independent myeloproliferative disease among chronic leukemias, which is accompanied by damage to the myeloid hematopoietic germ.
- Secondary polycythemia develops against the background of increased activity of erythropoietin. This is observed in chronic pulmonary pathologies, adrenal tumors, hemoglobinopathies and heart defects, which are accompanied by hypoxia. An increase in erythropoietin activity is a compensatory response of the body to chronic hypoxia.
How does polycythemia start? Stages of development of polycythemia
Polycythemia vera has 3 stages of development:
- 1 stage – oligosymptomatic, which lasts for several years and is characterized by the absence of clinical manifestations or an oligosymptomatic course. There is hypervolemia and slight erythrocytosis.
- Stage 2 – erythremic, can occur with and without myeloid transformation. With myeloid transformation, hypervolemia, splenomegaly, hepatomegaly, and pancytosis are observed in the peripheral blood. In the absence of myeloid transformation, erythrocytosis and thrombocytosis are noted, hyperplasia of all germs is visible on the myelogram.
- Stage 3 – anemic, characterized by leukopenia, a decrease in the number of platelets, myeloid transformation of the liver and spleen. At this stage, outcomes of polycythemia in terminal forms are possible.
You can learn about the clinical manifestations, methods of diagnosis and treatment of polycythemia in our next article.
Share:
Add a comment