Internal Medicine => Hematology
Hematology, medical specialty concerned with the study of blood and blood-forming tissues. Physicians in this field are known as hematologists. They study, diagnose, and treat blood disorders such as leukemia, anemia, and hemophilia, as well as diseases of the organs that produce blood, including the lymph nodes, bone marrow, and spleen.
Hematologists use laboratory-based blood tests to diagnose a variety of disorders. Of particular importance are blood tests that provide information about the cellular components of a patient's blood. The most common test, called a complete blood count (CBC), indicates the number of red blood cells, white blood cells, and platelets in a given unit of blood. Hematologists also examine blood samples under a microscope to identify abnormal blood cells and diagnose blood diseases. In addition to testing for blood diseases, hematologists may also be called on to diagnose other types of disorders, such as hepatitis C, a chronic liver disease that is detected in the blood.
Hematologists treat chronic blood disorders such as leukemia, a broad group of cancerous diseases of blood-forming organs. The condition affects white blood cells and is usually diagnosed by blood tests that indicate abnormal numbers of these cells. Treatment, which often is coordinated by hematologists and cancer specialists called oncologists, typically involves a combination of drug and radiation therapy and may also include a bone marrow transplant (see Medical Transplantation).
Another blood disorder commonly treated by hematologists is anemia, a deficiency of hemoglobin, the component of red blood cells responsible for transporting oxygen. The disorder, which reduces the oxygen-carrying capability of blood, is often caused by the inability of the bone marrow to produce enough new red blood cells. Hematologists detect anemia with a blood test and treat the various types of the disease with such methods as vitamin and mineral supplements, hormone therapy, and blood transfusions.
Hemophilia, a genetic blood disorder studied and treated by hematologists, impairs blood clotting. The disease is detected by a blood test; more recently, genetic tests have been used to diagnose hemophilia as well as to determine a parent's risk of passing the disorder to the next generation. People with hemophilia usually receive transfusions of plasma, the fluid component of blood, containing concentrated doses of a protein that aids clotting.
In recent years hematologists have undertaken serious efforts to improve the safety of the blood supply. In the past, blood transfusions were implicated in the spread of infectious diseases transmitted by contaminated blood. With biochemists, hematologists developed screening tests to detect the presence of many infectious diseases, including several forms of viral hepatitis and acquired immune deficiency syndrome (AIDS). Donated blood is now screened for infectious diseases to ensure its safety before it is used in transfusions.
Those seeking a career in hematology must obtain a medical degree and complete a three-year in-hospital training program called a residency, followed by one or two years of additional clinical training in hematology.