Erythrocytosis means there is a high number of red blood cells, also called erythrocytes, in a person’s blood. A person’s red blood cells are created in his bone marrow and used to move oxygen from his lungs to other parts of the body that need it. A high red blood cell count may indicate a range of conditions. For example, it could mean there is a problem with a person’s heart, lung, or kidney function. Sometimes it occurs because the bone marrow is producing abnormally high amounts of red blood cells or because the red blood cells are aren’t carrying as much oxygen as they should.
One condition a person may have when he has a high red blood cell count is congenital heart disease. Congenital heart disease is a heart defect or condition that has been present since birth. There are many different types of congenital heart problems a person may have, but many of them are accompanied by an elevated red blood cell count, shortness of breath, and difficulty with performing physical exercise.
A high red blood cell count may also indicate that a person has chronic obstructive pulmonary disease (COPD). COPD is a lung disease in which a person’s airflow is impaired and breathing is harder than it should be. Often, a person’s symptoms become progressively worse, and a person finds breathing even more difficult as time passes.
Dehydration may also contribute to a higher than normal red blood cell count. An individual may become dehydrated when he loses a lot of fluids and is unable to replace them quickly enough. For example, a person may become dehydrated when he has diarrhea or vomits and is unable to consume enough liquids to make up for those he’s lost. Sometimes a person may also become dehydrated in relation to a fever or because he is sweating much more than normal.
It’s important to note that a high red blood cell count may be the result of either a temporary or chronic condition. It is practically impossible for a person to determine its cause without a medical professional's help. If an individual has been told his red blood cell count is high, he’ll typically need to see his doctor for further evaluation and testing to determine the cause of the change. If an individual has already been diagnosed with a condition known for causing high blood cell counts, however, his doctor may be able to determine its cause with fewer tests.