foot and mouth Urine tests can reveal infections in the kidneys, the bladder, and the rest of the urinary tract. The chemical and cell content of urine can also show how well the digestive system is working. Urine can be tested in four different ways. First, it can be examined visually for color and texture. Normal urine is a clear yellow; if it is cloudy, reddish, or some other color, an infection or an injury may be present in the body. Second, the water content of the urine can be measured. This shows how well the kidneys are doing their job of filtering the body's wastes. Third, the chemical content of the urine can be analyzed, to find out if the body is discarding necessary chemicals that should be retained. Finally, the urine can be examined under a microscope to find out what cells, bacteria, and other material are present. Chemical analysis of urine is often used as a screening test for diabetes, a disease in which the body does not properly use the carbohydrates (sugars and starches) that are its chief sources of energy. To test for diabetes, the amount of glucose (a form of sugar) in the urine is measured by dipping a chemically treated stick in the urine and comparing the color of the stick with a color chart. If the glucose concentration is above a certain level, diabetes may be the cause. Blood tests are then done to verify the diagnosis. BLOOD TESTS Blood circulates throughout the body, so the contents of the blood can provide information both about general health and about specific diseases. The blood to be tested is drawn out of a vein with a syringe or taken by pricking a finger. The method used to take a sample depends on how much blood is needed for the tests that are to be done, and also how "clean" the specimen needs to be. A fingerstick sample is more likely to be contaminated by contact with the surface of the finger than is a sample taken by putting a sterile needle into a vein. Many different tests can be done on the blood, and a few of the most common ones are described here. More complex tests can be done to find out what chemicals are present in the blood. Hematocrit. This test is done to find out how much of the blood is made up of red blood cells, which carry oxygen to the body tissues. This is one of two tests done to check for anemia (red blood cell deficiency). A blood sample is spun in a machine called a centrifuge, which makes it separate into red blood cells, white blood cells, and plasma. The red cells are the heaviest, so they sink to the bottom. The percentage of red cells is then determined and compared with the normal range. Hemoglobin. Hemoglobin is a protein that gives red blood cells their red color; it combines with oxygen so that it can be carried in the blood. The amount of hemoglobin in the blood is tested by adding certain chemicals to the blood and then measuring the intensity of the red color that signifies the presence of hemoglobin. A hemoglobin test is often done at the same time as a hematocrit. incubation