A high red blood cell count is usually accompanied by an increased red blood cell pressure product, which can be caused by a variety of reasons, including blood concentration and increased red blood cell synthesis. Erythrocyte pressure volume, also known as hematocrit, is the ratio of the volume of blood occupied by red blood cells to the total volume of blood, and a high red blood cell count usually results in an elevated Erythrocyte pressure volume. A high red blood cell count is usually caused by the following reasons: loss of large amounts of body fluids and concentration of blood, such as severe diarrhea, and increased red blood cell synthesis, such as true erythrocytosis and pulmonary heart disease. If you have a high red blood cell count, you should go to the hospital to find out the cause to avoid delaying your condition.