Common blood test categories are interpreted according to whether they are higher or lower than a normal range. The four most common tests are the complete blood count, blood chemistry tests, blood enzyme tests and blood tests for heart disease risk, as the National Heart, Lung, and Blood Institute indicates.
The most common blood test is the complete blood count, according to the National Heart, Lung, and Blood Institute. Part of routine checkups, doctors use the test to detect blood diseases and disorders such as anemia and blood cancers. The measurements of different parts of the blood, such as red blood cells, white blood cells, hemoglobin, hematocrit and mean corpuscle volume, help doctors determine the level of risk and the condition in question.
Abnormal red blood cells indicate anemia, dehydration, bleeding or other blood disorders. White blood cell readings that are abnormal indicate an infection response is occurring because white blood cells fight diseases. Abnormal white blood cells also indicate immune system disorders, as the National Heart, Lung, and Blood Institute explains.
Platelet readings indicate blood clotting disorders when the blood clots too little or too much. High hematocrit levels signify dehydration, but low levels indicate anemia. Doctors also use hematocrit levels to determine the presence of a blood or bone marrow disorder. Abnormal hemoglobin readings indicate blood disorders such as thalassemia and sickle cell anemia. Mean corpuscle volume, an average of red blood vessel sizes, indicates anemia or thalassemia, according to the National Heart, Lung, and Blood Institute.