There are various types of blood tests which can all check for different things, including: Complete blood counts. A routine complete blood count (CBC) test checks for levels of 10 different components of red blood cells, white blood cells and platelets. Red blood cell count, hemoglobin, and hematocrit are all important components measured by this test. Abnormal levels of these components may indicate: • Nutritional deficiencies, such as vitamin B6 or B12 • Iron deficiency • Bone marrow issues • Tissue inflammation • Infection • Heart conditions Blood tests are also used in some STD tests and can detect: • Chlamydia • Gonorrhea • Herpes • HIV • Syphilis Coagulation tests check for underlying conditions that may affect clotting and results can be used to diagnose: • Acute myeloid leukemia • Excessive bleeding (hemophilia) • Thrombosis • Liver conditions • Vitamin K deficiency