Polycythemia is a blood disorder in which the bone marrow produces too many red blood cells, causing symptoms such as a headache, weakness and itching. Know its causes and what its treatment is.
Polycythemia is a disease characterized by an increase in a number of red blood cells in the bloodstream. There is a primary form (polycythemia), which presents an uncontrolled proliferation of red blood cells, white blood cells and platelets, and a secondary form, in which only red blood cells are increased in number and volume.
The polycythemia was first described in 1892 by Vaquez, while in 1903 Osler wrote "the disease is characterized by chronic cyanosis, polycythemia and moderate enlargement of the spleen. The main symptoms have been a weakness, prostration, constipation, headache and vertigo. For this reason, polycythemia is also called Vaquez-Osler disease.
Polycythemia usually has an insidious onset, more frequent during the sixth decade of life, although it can also begin in childhood or in middle age. The symptoms include a headache, facial flushing, itching, thrombosis, and gastrointestinal bleeding, but some patients are diagnosed because there are alterations in the results of a casual analysis. The symptoms reported by at least 30% of patients with polycythemia are, from more to less frequent headache, weakness, itching, dizziness and sweating.
In polycythemia, you will see that the symptoms do not appear suddenly, but they do advance slowly and progressively. It is quite common that polycythemia is detected accidentally, that is, when performing a basic blood test where a high number of red blood cells is revealed without any symptoms.
- Along with general symptoms such as fatigue and weight loss, the most frequent signs and symptoms of polycythemia are related to the increase in blood viscosity and the total volume of circulating blood (a headache, blurred vision, double vision, dizzying sensation, tinnitus). There could also be the perception of sounds that do not exist in the environment, tingling in the extremities, arterial hypertension.
- Symptoms of the very frequent polycythemia are itching, which appears characteristically during bathing or showering (hydrogenic or watery pruritus). It usually manifests with a sensation of itching on contact with hot water, which has been noticed for years without having consulted, and which does not correlate with any injury or redness of the skin. In addition, it is common for patients with polycythemia to have an enlarged spleen (splenomegaly), which occurs in 30-40% of cases.
- The digestive symptoms in the form of burning, gastroduodenal ulcers or erosive gastritis can be observed in these patients.
- Erythromelalgia appears in one-third of the patients with polycythemia, which is a burning sensation in some joints of the foot and hands. In this condition, there reddening of the skin in that area also occurs. Sometimes it can be accompanied by a sensation of corrugation, especially in patients with elevated platelets as well as erythrocytes.
- Sporadic or permanent reddening of the cheeks and nose (erythrosis or facial plethora) and swelling of the tissue lining the eyelids and conjunctiva of the eye (conjunctival chemosis) are other common symptoms in these patients.
Although there is no single cause of polycythemia, it is known that there are a number of factors that contribute to the abnormal production of red blood cells, which would be the origin of this blood disorder:
Causes of Polycythemia:
- Increased sensitivity to erythropoietin: The red blood cell precursors are more sensitive to the stimulus that erythropoietin generates to form erythrocytes or red blood cells.
- Alterations in hematopoietic factor receptors: this means that there is an abnormal response to stimuli of other blood substances (hematopoietic factors) in the receptors of a protein called thrombopoietin, which will lead to an uncontrolled and pathological formation of red blood cells.
- Chromosomal alterations: In a variable percentage of patients with polycythemia, abnormalities are detected in chromosomes 8, 9, 17 and 20 that could explain this disease. In the case of chromosome 9, there is a point mutation of the JAK2 gene, which has recently been cited as the most determining factor in the development of this disease. It is estimated that more than 90% of them express this mutation as a cause of polycythemia.
- Endogenous formation of red blood cells: It could be an individual predisposition without an alteration as well known as the previous ones, idiopathically. In these cases, patients present an exaggerated production of erythrocytes without the need for stimuli such as erythropoietin, without evidence of alterations in their receptors or other factors.
Polycythemia is characterized by an increase in the number of red blood cells, and there are two types of polycythemia:
- Primary polycythemia or polycythemia is an alteration of the hematopoietic stem cell (precursor cell that gives rise to different blood cells), characterized by an uncontrolled proliferation of blood cells (white blood cells, red blood cells and platelets). Although the predominance of red blood cells is the characteristic feature of the disease, the increase in white blood cells and platelets is also frequent.
The causes of the malignant transformation that occurs in polycythemia are unknown. Its incidence is 0.7-2.6 cases per 100,000 people per year, and it is slightly more frequent in males, especially affecting people between the ages of 50 and 70 years. It is rare before age 40 (4% of cases).
- Secondary polycythemia or secondary erythrocytosis: refers to situations in which only red blood cells are increased in number. In turn, secondary polycythemia can be subdivided into:
- Appropriate polycythemia: the increase in the number of red blood cells occurs in response to hypoxia (low amount of oxygen in the blood). Such increases can be observed, for example, in people who live at high altitudes, in people who smoke a lot, and in patients with cardiopulmonary disease.
- Inappropriate polycythemia: If the formation of red blood cells (erythropoiesis) is triggered by the abnormal production of erythropoietin (EPO).For example, in people suffering from hereditary diseases or tumours
The performance of complementary tests such as a blood test or a study of the bone marrow is essential to reach the diagnosis.
In the blood analysis the doctor can observe some changes in the body that help in diagnosing this disease:
- The most outstanding fact is the increase in the number of red blood cells, haemoglobin and haematocrit (percentage of the volume of all blood that is due to red blood cells, a measurement that depends on the number of these and their size). The red cells are usually small and hypochromic (they have less colour than normal when examined under a microscope), due to the excessive iron consumption that occurs in the bone marrow.
- An increase in the number of white blood cells (leukocytosis) and platelets (thrombocytosis) is observed in 50% of patients.
- The ESR (erythrocyte sedimentation rate) is low.
- The vitamin B12 and blood uric acid are often low, and erythropoietin (EPO).
- The analysis of the bone marrow is another of the methods used for the study of polycythemia. The bone marrow is the soft tissue that is located inside the bones and that serves as a factory for blood cells. There are different techniques to obtain a sample of this, the most frequent being aspiration and spinal biopsy.
- Bone marrow aspiration: The process involves the extraction of a small quantity of the Bone Marrow in liquid form for its analysis. What is observed in the laboratory is an increase in the three hematopoietic series, that is, the precursor cells of red blood cells, white blood cells and platelets.
- Bone marrow biopsy: involves removing a portion of bone marrow from inside a bone. What is observed in 85% of cases is a hypercellular bone marrow, that is, there is an increase in the precursor cells of blood cells.
There is no effective strategy to prevent polycythemia. The prevention of secondary polycythemia focuses on preventing the causes of lung and heart disease, especially tobacco use.
Patients with polycythemia without treatment have a survival of only 18 months, while with proper treatment it is more than 15 years. The objective of the treatment is to reduce the thickness of the blood, as well as to avoid complications such as the formation of thrombi or the appearance of haemorrhages. The treatments used in polycythemia are the following:
- Phlebotomy: This constitutes the fundamental treatment in the polycythemia, and its objective is to reduce quickly the risk of thrombosis caused by the increase in the blood of the number of red blood cells. The immediate effect of bleeding or phlebotomies is to reduce the hematocrit, which causes an improvement in symptoms such as a headache. It does not reduce the number of white blood cells or platelets, nor does it affect symptoms such as itching. They usually extract about 450 ml of blood every 3-4 days. In people of advanced age or with cardiovascular problems it is not advisable to make such important extractions, and in those cases, it is recommended to perform blood draws of 200-300 ml two or three times a week.
- Antiaggregant: It involves the use of antiplatelet drugs, such as aspirin at low doses which reduces the risk of thrombi formation. This helps in avoiding complications such as myocardial infarction, cerebral infarction or pulmonary thromboembolism.
- Radioactive phosphorus: indicated in elderly patients who cannot follow controls with adequate regularity. It is administered intravenously in one dose, and its effect is observed after 2-3 months. If after this time the analytical parameters have not been normalized, another dose can be administered.
- Chemotherapy: you can use different substances such as hydroxyurea (the most used) or busulfan, used mainly for elderly people.
- Interferon and anagrelide: especially used in young patients. In general, it takes 6 to 18 months of treatment to get an answer, and it should be noted that up to a third of patients receiving this treatment leave it because of its side effects (symptoms similar to flu, depression, cardiovascular symptoms, etc).
The most frequent and serious complications of polycythemia are thrombotic phenomena (thrombi formation inside the blood vessels), both in the arteries (two-thirds of cases) and in the veins. They can occur even before the diagnosis of polycythemia has been established as the first manifestation of the disease. The thrombosis may affect blood vessels anywhere in the body, resulting in stroke, angina or myocardial infarction, pulmonary thromboembolism or thrombosis of abdominal veins or extremities.
- The diagnosis is especially suggestive in women under 45 years of age who, for no other apparent reason, have thrombosis of the mesenteric veins, the suprahepatic veins or the portal system.
- In about half of the patients, there may be transient blindness (amaurosis) of one of the eyes, which usually recovers in a few hours. This is due to the hyperviscosity of the blood in this disease.
- Hemorrhagic complications (bleeding) occur in 30-40% of patients during the course of the disease, in the form of gastrointestinal bleeding (individuals with polycythemia have an increased incidence of peptic ulcer) or nosebleeds (epistaxis).
Myth #1: Having Polycythemia puts your heart at risk:
Although the disease thickens the blood, with proper treatment it is a symptom that can and should be controlled. So only 30% of patients with Polycythemia register cardiac complications associated with clots or blockage of veins and arteries.
Myth #2: Patients with Polycythemia cannot perform physical activities:
The Polycythemia is a disease that by thickening the blood hinders the correct oxygenation of the body, so it is important to perform exercises that stimulate and improve the respiratory system. The treating physician should be constantly consulted about the exercises that are carried out, in order to evaluate the signs and to make progress or recommend improvements.
Myth #3: Polycythemia only affects the elderly:
This disease is diagnosed more frequently in people older than 55 years, however, it can also occur in children and adults under 40 years; so, it is important to be attentive to the symptoms and when in doubt go to a hematologist who performs the necessary diagnostic tests for proper treatment.
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