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What Is Erythrocytosis?

By H. Colledge
Updated Mar 03, 2024
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Erythrocytosis is a condition in which there is an abnormally high number of red blood cells, or erythrocytes, in the circulation. What is called primary erythrocytosis may be caused by a rare bone marrow disorder, known as polycythemia vera, where the bone marrow produces too many red cells. More commonly, what is known as secondary erythrocytosis occurs. This is usually the result of an existing medical disorder, such as a long-term lung disease, where tissues have become starved of oxygen and high levels of a protein known as erythropoietin have been released, stimulating red blood cell production. What is called apparent erythrocytosis may also occur, where the overall volume of blood plasma is decreased, making the red blood cells appear more concentrated.

Whatever the cause of the condition, symptoms may not be apparent in the early stages and the condition may be discovered from routine blood tests. Vague symptoms such as tiredness may be present and sometimes sweating, itching, dizziness and headaches may be experienced. For people who have polycythemia vera, there is an increased risk of blood clots occurring and in some cases the first sign of the condition may be a thrombosis, or clot, inside a blood vessel, causing a problem such as a stroke or heart attack. The UK spelling of polycythemia vera is polycythaemia vera, and it may also be known as polycythaemia rubra vera.

People who have secondary erythrocytosis may also have a greater risk of thrombosis but it is thought to be less than for those who have polycythemia vera. It is not known whether having apparent erythrocytosis increases a person's thrombosis risk. Reductions in blood plasma volume, which lead to an apparent increase in red blood cells, may be caused by alcoholism, heavy smoking or the use of diuretic drugs which remove fluid from the body.

The treatment depends on the cause. Secondary forms of the condition require treatment of the underlying disorder, and the outlook will depend on how successful this is. In the case of a long-term lung disease, giving oxygen may help reduce the levels of erythropoietin and decrease red blood cell numbers.

For the primary condition, if the rare blood disease polycythemia vera is the cause, the outlook is poor without treatment. There is a high risk of a fatal stroke or heart attack occurring within 18 months. With treatment, the outlook improves to give an estimated life expectancy of about 20 years. Treatment methods include removing blood from the circulation, taking aspirin to lower the risk of clotting and taking medication to lower the number of blood cells.

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Discussion Comments

By anon989919 — On Mar 27, 2015

Erythrocytosis, is increased erythropoietin, and is not associated with any health problems. Living in high altitude can do this. The problem with polycythemia vera is abnormal bone marrow producing to much. Its the cancer that increases stroke and heart attacks, not the blood. A stroke and MI is lack of blood flow. Hgb does not block blood flow. Now roleau from cancer will do that, or sickling from sickle cell will also.

By anon984938 — On Jan 12, 2015

I have been diagnosed with erythrocytosis, but my hemoglobin levels fluctuations correspond with testosterone levels. The higher my testosterone, the higher my hemo count. I am on synthetic androgen. My doctor referred me to an oncologist but I think I need to look at a different form of Androgen because there is no doubt that the topical Androgen is the root cause of the problem. I'm putting the oncology option on hold until I see a urologist.

By Grivusangel — On Mar 18, 2014

My mom is a retired lab technician and said they had a patient at the last office where she worked who had polycythemia. She said he did very well with it, and came in about every two months to have a pint of blood drawn to help cut down on the numbers of red blood cells. As I recall, he lived a long life. I don't know what caused the erythrocytosis, but my mom said he had polycythemia, whatever its root cause may have been. He always had a high hematocrit, but she said it would drop after she drew that pint of blood.

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