What Is Polycythemia Vera?

Polycythemia refers to the number of red blood cells and hemoglobin per unit volume of blood above the upper limit of the reference value. Repeated examinations of adult male red blood cell counts> 6.0 × 10 ¹² / L, hemoglobin> 170g / L, adult female red blood cell counts> 5.5 × 10 ¹² / L, and hemoglobin> 160g / L are considered to be increased. Polycythemia can first be divided into relative and absolute increases, the latter can be divided into two major categories: primary and secondary. The primary can be divided into congenital and acquired acquired, the latter usually refers to true erythrocytosis.

Basic Information

English name

erythrocytosis

Visiting department

Hematology

Common causes

Relative increase, secondary erythrocytosis

Contagious

no

Causes of erythrocytosis

Increase in relativity

It means that the volume of plasma decreases, which makes the volume of red blood cells relatively increase. Seen in severe vomiting, diarrhea, heavy sweating, extensive burns, chronic adrenal insufficiency, diabetes insipidus, hyperthyroidism, and diabetic ketoacidosis.

2. Secondary erythrocytosis

It is caused by an increase in erythropoietin in the blood, and the increase in EPO can be congenital or caused by acquired factors.

(1) Acquired EPO increase The following reasons are common: Compensative increase of erythropoietin: caused by decreased blood oxygen saturation. The degree of red blood cell increase is directly proportional to the degree of hypoxia. Compensatory increase in physiological erythropoietin is seen in fetuses and newborns, and residents of plateau areas. Pathological increase is seen in severe chronic heart and lung disorders such as obstructive emphysema, pulmonary heart disease, congenital heart disease with cyanosis, and abnormal hemoglobin disease with low oxygen carrying capacity. Non-compensatory increase of erythropoietin: The increase of erythropoietin is related to certain tumors or kidney diseases, such as kidney cancer, hepatocellular carcinoma, ovarian cancer, renal embryo cancer, adrenocortical adenoma, uterine fibroids and hydronephrosis Polycystic kidney disease.

(2) The increase of congenital EPO is mainly caused by the congenital high-affinity hemoglobin production and the spontaneous overproduction of congenital EPO.

3. Primary erythrocytosis

(1) Congenital primary erythrocytosis Due to mutations in the EPO receptor gene, red blood cells are increased.

(2) Acquired primary erythrocytosis, that is, erythrocytosis is a proliferative tumor of bone marrow that is dominated by erythrocytosis, and is currently thought to be caused by a mutation in the JAK2-V617F pluripotent hematopoietic stem cell.

Polycythemia diagnosis

Adult men with red blood cell counts> 6.0 × 10 ¹² / L, hemoglobin> 170g / L, adult women with red blood cell counts> 5.5 × 10 ¹² / L, and hemoglobin> 160g / L are considered compatible with erythrocytosis. The etiology and classification of hyperplasia is the key.

Polycythemia treatment

For secondary acquired erythrocytosis, the treatment mainly starts from the cause. For erythrocytosis, the main goal of treatment is to avoid and reduce thrombotic events, followed by avoiding and delaying the disease progression to myelofibrosis and acute leukemia. Therefore, the commonly used treatments are as follows:

1. Long-term low-dose aspirin oral

Can significantly reduce the incidence of thrombotic events.

2. Venous bleeding

Not only can it quickly reduce hemoglobin levels, but it can also reduce the progression of long-term patients to bone marrow fibrosis and acute leukemia. Can use ordinary bloodletting or apheresis technique. Venous bloodletting is not a fundamental treatment for erythrocytosis, so long-term adherence or combination with other treatments is needed.

3. Cytostatic therapy

Long-term oral hydroxyurea is the most commonly used method. Interferon can also be used alone or in combination. Marilenland and isotope 32P have also been used to reduce the number of red blood cells, but after long-term use, patients are at increased risk for myelofibrosis and acute leukemia, so they have not been recommended in recent years. Recent studies have found that after cytostatic treatment, if the hematocrit is less than 45%, the thrombotic events in patients can be significantly reduced.

4.JAK2 inhibitor

Since the onset of polycythemia vera is closely related to the activation of the JAK2 pathway, the targeted therapeutic drugs designed for this pathway have achieved great success in recent years. Among them, Ruxolitinib, which was first marketed, has shown good efficacy in clinical studies, Hemoglobin levels have significantly decreased, and significantly improved patients' quality of life and reduced the risk of thrombotic events, thereby enabling patients to achieve longer survival times.