What is Hematology? - Definition & History

Instructor: Danielle Haak

Danielle has a PhD in Natural Resource Sciences and a MSc in Biological Sciences

Hematology is the branch of science that focuses on the health and diseases of the blood. Read on to learn about the study of blood, major scientific advances in hematology, and common diseases that can affect the blood.

What is Hematology?

If you've ever been really sick, you may have had blood drawn for analysis. Our blood can hold secrets that aren't readily visible to the naked eye. When the blood fails to function normally, diseases such as anemia, clotting disorders, leukemia, and a number of others can occur. The study of blood and its disorders is called hematology.

Scientists or doctors who study the blood are called hematologists, and they specifically look at blood health and blood diseases. Blood is composed of red blood cells, white blood cells, and platelets. Organs of the body affected by, or used to, transport blood include the blood vessels, bone marrow, lymph nodes, and spleen. Proteins in the body are also involved in bleeding and clotting.

History of Hematology

The history of hematology dates back to ancient Egypt and the use of blood-letting tools. A major breakthrough in the study of blood occurred in 1642 when Anthony van Leeuwenhoek built a microscope and identified blood cells. In 1770, William Hewson, the 'Father of Hematology', introduced the clotting features of blood and shared his knowledge of leukocytes, or white blood cells. It wasn't until 1818 that James Blundell successfully completed the first recorded blood transfusion between humans, but the world would have to wait almost another hundred years before Reuben Ottenberg used blood typing to conduct transfusions and identified the universality of type O blood.

Here are some other important dates associated with the history of hematology:

  • 1901: Karl Landsteiner and his associates define the different blood groups: A, B, AB, and O.
  • 1914: Richard Lewisohn discovers how sodium citrate can be used to store blood.
  • 1936: The first blood bank opens in Chicago.
  • 1961: The role of platelets in treating cancer patients is identified.
  • 1971: Healthcare professionals in the United States start testing blood for Hepatitis B.
  • 1983: Doctors in France and the United States discover the human immunodeficiency virus (HIV).
  • 1987: The Food and Drug Administration approves the use of azidothymidine (AZT) to treat HIV.
  • 1990s: Recombinant factor replacement products are used to treat hemophilia.

Diseases Affecting the Blood

Approximately three million people in the United States suffer from anemia, which is the most common type of blood disorder. In this disease, there are not enough red blood cells in the body, or the red blood cells malfunction and don't carry enough hemoglobin, an important protein that is rich in iron. Anemic people suffer from dizziness, irregular heartbeat, shortness of breath, and weakness, among other symptoms. A poor diet is the most common cause of anemia, so you should talk with your doctor to make sure your own daily food intake includes all the nutrients you need to stay healthy.

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