Secondary Polycythemia (Secondary Erythrocytosis)

Erythrocytosis is a common blood disorder that occurs when there are too many red blood cells (RBC) or white blood cells (WBC). These abnormal RBCs may cause anemia, which causes your body’s ability to fight infection and other diseases to decrease. When you have erythrocytosis, your red blood cell count decreases because of the presence of abnormally large numbers of these abnormal RBCs.

The most common type of erythrocytosis is called hemolytic erythroidism. Hemolytic erythroidism is caused by a genetic defect in the production of factor VIII, which helps convert excess amounts of protein into energy for your body. Factor VIII deficiency leads to the breakdown of red blood cells and anemia. Other types of erythrocytosis include:

Polycythemia Vera (PCV), also known as Factor V Leiden (FvL), is a rare condition that affects 1 out of every 100,000 to one out of every 10 million people. This condition is a mutated gene that causes blood to make natural antibodies that destroy platelets. Without proper treatment, patients with PCV have an increased risk of developing blood clots and having heart attacks and strokes.

Megaloblastic Anemia (MA), is caused by a lack of folate, which prevents your body from converting food into usable energy. Without adequate amounts of folate, your body cannot produce or maintain enough healthy RBCs.

Hemoglobinopathies (Hb), are caused by an abnormal form of hemoglobin, a key part of your RBCs that makes them red. Abnormal forms of hemoglobin can also be passed down from parents to children. The two most common types are sickle-cell anemia and thalassemia. Both of these conditions can cause a variety of health problems.

Sickle-cell Anemia (SCA), is an inherited disease in which your body produces abnormal hemoglobin called “sickle hemoglobin.” This type of hemoglobin causes your red blood cells to become rigid and sickle shaped. These rigid, sickle-shaped cells are fragile and break easily, causing you to miss essential nutrients and oxygen that your body needs to survive. Sickle-cell anemia is relatively common among people of African, Middle Eastern, and Mediterranean descent.

Thalassemia is an inherited blood disorder in which you are unable to produce two key types of hemoglobin: alpha globin and beta globin. This causes your body to produce a reduced amount of functional red blood cells and reduces the body’s ability to get enough oxygen to the organs. There are two main types of thalassemia:

Major Thalassemia (MT), which decreases the body’s ability to produce alpha globin, a type of hemoglobin that carries oxygen to the body’s organs.

Intermedia Thalassemia (IT), which decreases the body’s ability to produce beta-globin, a type of hemoglobin that carries oxygen to the body’s organs.

The best treatment for erythrocytosis is to bring the number of RBCs back to normal levels. If the RBC count is very high, you may need a blood transfusion to restore this to a safe range. Some types of erythrocytosis can be treated with medication, such as an injection of the hormone erythropoietin, which stimulates your body’s production of RBCs.

Treatments for erythrocytosis can be contraindicated in some patients and may not solve all of the issues with anemia, including low levels iron and folate. Discuss the various treatment options with your physician to find a solution that best fits your specific needs.

Sources & references used in this article:

Secondary polycythemia: a boon or a burden? by AJ Erslev, J Caro – Blood Cells, 1984 –

Quantification of PRV-1 mRNA distinguishes polycythemia vera from secondary erythrocytosis by S Klippel, E Strunck, S Temerinac, AJ Bench… – Blood, 2003 –

Immunohistochemical staining for megakaryocyte c-mpl may complement morphologic distinction between polycythemia vera and secondary erythrocytosis by A Tefferi, SY Yoon, CY Li – Blood, The Journal of the American …, 2000 –

Secondary polycythemia associated with idiopathic membranous nephropathy by CS Lim, KH Jung, YS Kim, C Ahn, JS Han… – American journal of …, 2000 –

A guideline for the management of specific situations in polycythaemia vera and secondary erythrocytosis: a British Society for Haematology Guideline by MFF McMullin, AJ Mead, S Ali, C Cargo… – British journal of …, 2019 –

Does untreated obstructive sleep apnea cause secondary erythrocytosis? by CD Nguyen, JEC Holty – Respiratory medicine, 2017 – Elsevier