What Causes High Blood Cell Counts?

High blood cell counts can be a result of a condition that increases the bone marrow's production of white or red blood cells, according to Mayo Clinic. White blood cell production increases when the body needs to fight an infection or as a reaction to an immune system disorder or certain medication. High red blood cell counts can occur because the body needs to compensate for low oxygen levels at high altitudes or due to poor lung or heart function.

Leukocytosis or a high white blood cell count can be a result of anemia, leukemia, tissue damage, cigarette smoking or certain medications, explains MedlinePlus. Infections, inflammatory diseases and extreme physical or mental stress are other common factors that lead to lekocytosis. Taking drugs such as beta adrenergic agonists, epinephrine, corticosteroids, heparin and lithium can contribute to a high white blood cell count.

Sleep apnea, anabolic steroids, heart failure, carbon monoxide poisoning and congenital heart disease in adults can cause a high red blood cell count, notes Mayo Clinic. When the kidneys release too much erythropoietin, it enhances the production of red blood cells as well. The depletion of sodium and water can also cause a loss of the liquid component of blood or blood plasma, leading to higher red blood cell levels.