A red blood cell (RBC) count is a blood test that measures the number of red blood cells (RBCs) in a blood sample. Normal range of RBC count is 4.5 to 5.5 million cells/cubic mm. The test is a part of the most routine complete blood count (CBC) test.
Low levels of RBCs are seen in iron deficiency anaemia, thalassemia, stomach ulcers, sickle cell anaemia and certain cancers. The oxygen supply to the body is decreased leading to fatigue and weakness or anaemia. High RBC count is seen in case of chronic smokers, alcoholics and in people with long-term lung, kidney, heart or liver disease. The count may also be increased in cases of dehydration, burns, diarrhoea and vomiting. If the levels of RBCs are higher than normal, they stick to each other, form clumps and block blood vessels.