What does high hematocrit mean?

Some causes of a high hematocrit include:

– Dehydration—this is the most common cause of a high hematocrit. As the volume of fluid in the blood drops, the RBCs per volume of fluid artificially rises; with adequate fluid intake, the hematocrit returns to normal.

– Lung (pulmonary) disease—if someone is unable to breathe in and absorb sufficient oxygen, the body tries to compensate by producing more red blood cells.

– Congenital heart disease—in some forms, there is an abnormal connection between the two sides of the heart, leading to reduced oxygen levels in the blood. The body tries to compensate by producing more red blood cells.

– Kidney tumor that produces excess erythropoietin

– Smoking

– Living at high altitudes (a compensation for decreased oxygen in the air)

– Genetic causes (altered oxygen sensing, abnormality in hemoglobin oxygen release)

– Polycythemia vera—a rare disease in which the body produces excess RBCs inappropriately.

A high hematocrit with a high RBC count and high hemoglobin indicates polycythemia. Polycythemia (also known as polycythaemia or polyglobulia) is a disease state in which the proportion of blood volume that is occupied by red blood cells increases.