Several medical conditions ﾖ dehydration, cigarette smoking and certain medications ﾖ may cause high red blood cell counts, according to MedlinePlus. To intentionally increase low red blood cell counts as treatment for anemic patients, options include vitamin and mineral supplementation, blood transfusion and medication.
Congenital heart disease and right-sided heart failure are two causes of abnormally high red blood cell counts, according to MedlinePlus. A low blood oxygen level or dehydration can also cause an increase in red blood cells. Bone marrow disease, a type of kidney tumor called renal cell carcinoma, and a kind of lung damage known as pulmonary fibrosis also can cause high counts.
The Mayo Clinic also names chronic obstructive pulmonary disease and sleep apnea as causes of high red blood cell counts.
MedlinePlus names two drugs, gentamicin and methyldopa, that may lead to high red blood cell counts. Gentamicin is an antibiotic used to treat serious infections, and methyldopa is used to lower high blood pressure, according to Drugs.com. The Mayo Clinic lists as other causes the use of anabolic steroids and "EPO doping" (injection of the protein erythropoietin). EPO doping is used to improve athletic performance.
The Mayo Clinic notes that red blood cell counts increase when a person moves to a higher altitude where less oxygen is available. However, MedlinePlus says this effect lasts for just several weeks.