Erythrocytosis means that there are a large number of red blood cells, also called erythrocytes, in a person's blood. A person's red blood cells are created in their bone marrow and are used to move oxygen from their lungs to other parts of the body that need it. A high red blood cell count can indicate a variety of conditions. For example, it could mean there is a problem with a person's heart, lung, or kidney function. It sometimes happens because the bone marrow makes abnormally high numbers of red blood cells or because the red blood cells don't carry as much oxygen as they should.
One condition that a person can have when they have 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 that a person can have, but many of them are accompanied by high red blood cell counts, shortness of breath, and difficulty exercising.
A high red blood cell count can also indicate that a person has chronic obstructive pulmonary disease (COPD). COPD is a lung disease in which a person's airflow is affected and breathing is more difficult than it should be. Often, a person's symptoms get progressively worse and a person finds it even more difficult to breathe as time goes on.
Dehydration can also contribute to a higher-than-normal red blood cell count. An individual can become dehydrated when they lose too much fluid and cannot replace it quickly enough. For example, a person can become dehydrated when they have diarrhea or vomiting and are unable to consume enough fluids to make up for what they have lost. Sometimes a person can also become dehydrated in connection with a fever or because they are sweating a lot more than normal.
It is important to note that a high red blood cell count may be the result of a temporary or chronic condition. It is virtually impossible for a person to determine its cause without the help of a medical professional. If an individual has been told that their red blood cell count is high, they will usually need to see their doctor for further evaluation and tests to determine the cause of the change. However, if a person has already been diagnosed with a condition known to cause high blood cell counts, their doctor may be able to determine the cause of it with fewer tests.