An elevated red blood cell count is associated with dehydration, congenital heart disease, kidney tumors, bone marrow diseases and scarring of the lungs, reports MedlinePlus. Red blood cells contain hemoglobin, a protein that transports oxygen.
In men, a normal red blood cell count ranges from 4.7 to 6.1 million cells per microliter of blood, states MedlinePlus. Women have a slightly lower normal range of 4.2 to 5.4 million cells per microliter. The medications gentamicin and methyldopa are known to increase the number of RBCs in the blood. Moving to a high-altitude area can cause an increase as well. Other causes of a high RBC count include cigarette smoking, a low blood oxygen level and right-sided heart failure.