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October 02, 2023
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What is hematology?

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This article, previously posted on March 23, 2022, has been republished to include website enhancements.

Hematology is the science or study of blood and blood diseases.

Scrabble tiles on a table spell out 'lymphoma.'
Hematology is the science or study of blood and blood diseases, and it is frequently associated with oncology. Image: Adobe Stock

In the medical field, hematology includes the treatment of blood disorders and malignancies, including types of hemophilia, blood clots, leukemia, lymphoma, myeloma and sickle-cell anemia. Hematology is a branch of internal medicine that deals with the physiology, pathology, etiology, diagnosis, treatment, prognosis and prevention of blood-related disorders.

Hematologists focus largely on lymphatic systems and bone marrow and may diagnose blood count irregularities or platelet irregularities. Hematologists treat organs that are fed by blood cells, including the lymph nodes, spleen, thymus and lymphoid tissue.

Anatomy of blood

Blood is made up of several parts, including red blood cells, white blood cells and platelets (combined, about 45% of volume) as well as plasma (about 55% of volume). Red blood cells (also known as RBCs or erythrocytes), which make up about 45% of whole blood, carry oxygen from the lungs to the body’s tissue. They also carry carbon dioxide back to the lungs to be exhaled. They are disc-shaped and produced in the bone marrow.

White blood cells (also known as WBCs or leukocytes), which are also made in the marrow, help fight infection. Together with platelets, they make up less than 1% of whole blood. Platelets (also called thrombocytes) are small, colorless fragments that stick together and interact with clotting proteins to stop or prevent bleeding. They are also produced in bone marrow.

Plasma is the yellowish fluid part of the blood. Composed of 92% water, it also contains 7% vital proteins and 1% mineral salts, sugars, fats, hormones and vitamins.

Areas of study

Four major areas of study within hematology include hemoglobinopathy, hematologic malignancies, anemia and coagulopathy. Hemoglobinopathy is the study of abnormality in the globin chains of hemoglobin molecules. In addition to sickle cell anemia, thalassemia (also known as erythropoiesis) is part of hemoglobinopathy.

The area of hematologic malignancies is concerned with the diagnosis and treatment of cancers of the bone marrow, blood and lymph nodes. Myeloma is one type of hematologic malignancy, along with leukemia and lymphoma. Other disorders treated by a hematologist include arterial thromboembolism, deep-vein thrombosis and neutropenia.

Hematology oncology

Although hematologists work together with experts from various medical and surgical specialties, hematology is most often linked with oncology. Hematologists and oncologists work together to care for adults and children with cancers of the blood and bone marrow, including leukemia and lymphoma.

Hematology tests

One of the most common hematology tests is the complete blood count, or CBC. This test is often conducted during a routine exam and can detect anemia, clotting problems, blood cancers, immune system disorders and infections. 

Other hematology tests include:

  • blood chemistry test;
  • blood enzyme test; and
  • blood tests to assess heart disease risk.

Additional information can be found by searching the following websites:

www.accc-cancer.org/home/learn/cancer-types/hematologic-malignancies

www.acponline.org/about-acp/about-internal-medicine/subspecialties-of-internal-medicine/hematology

www.hematology.org/education/patients/blood-disorders

www.hopkinsmedicine.org/health/treatment-tests-and-therapies/hematology

www.mayoclinic.org/departments-centers/hematology/sections/overview/ovc-20201283medlineplus.gov/ency/article/001291.htm

www.nhlbi.nih.gov/health/anemia

www.nhlbi.nih.gov/health/blood-tests

www.redcrossblood.org/donate-blood/how-to-donate/types-of-blood-donations/blood-components.html

www.uclahealth.org/mattel/pediatric-hematology-oncology/hematology-disorders