Laboratory studies of blood, urine or joint (synovial) fluids are used to identify the presence and amount of chemicals, proteins, and other substances. Your doctor may order various laboratory studies depending on what he or she finds during the initial examination. For example, laboratory studies can identify the amount of uric acid in the blood, which is an indicator of gout. A high white blood cell count in joint fluid may indicate severe inflammation or infection. Laboratory tests are usually required before surgeries to identify medical abnormalities.
You may be required to fast for a specific number of hours before donating samples for a laboratory test.