What could cause my red blood count to be elevated?

There are several things that can cause your red blood cell count, or similar lab tests such as hemoglobin and hematocrit, to be high. The most common is dehydration, because of a relative concentration of your red blood cells compared to the amount of fluid, or "plasma," in your bloodstream. Another common cause of a high red blood cell count is having a health condition that makes the amount of oxygen in your blood chronically low, such as chronic obstructive pulmonary disease (COPD). More concerning things that can cause this would be your body making too many red blood cells without a cause, a condition called polycythemia. Only your doctor can tell you which one of these conditions may be causing your elevated red blood cells.