Tests that study the blood cells. Blood tests may be taken by a finger stick or drawn from a vein in the arm using a needle. Blood tests are used to measure the red blood and white blood cell count, hematocrit, hemoglobin, prothrombin and platelet count. Tests the amount of substances carried in the blood. Blood chemistry tests study the amount of sugar, drugs and poisons, creatinine, blood urea nitrogen, uric acid, bilirubin, calcium, or protein in the blood and many other components.
Antigens are substances that cause a reaction in blood or tissues.
Antibodies are produced to fight antigens. Blood may be tested for blood type and RH factor, evidence of exposure to disease. These tests may also check for enzymes or microbes. Biopsy, Pap tests, throat culture, spinal tap, sputum test, stool sample and gastric juice are examples of specimen and tissue tests.