What is Hematology?

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

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 the 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.

What is a hematologist?

A hematologist is a specialist in hematology, the science or study of blood, blood-forming organs, and blood diseases.

The medical aspect of hematology is concerned with the treatment of blood disorders and malignancies, including types of hemophilia, leukemia, lymphoma, 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.

Education

Becoming a hematologist requires 7 or more years of medical school and postgraduate training, before earning a board certification in internal medicine.

In addition, at least 2 years of specialty training, studying a range of hematologic disorders, are required. Hematologists can later gain further certification in a subspecialty.

Specialty areas

Hematologists work in various settings, including blood banks, pathology laboratories, and private clinics. Specialists in this branch of medicine, such as hematopathologists, can choose to focus on specific topics within the field of hematology (e.g. lymphatic organs, bone marrow) and may diagnose blood count irregularities or platelet irregularities. They are able to treat organs that are fed by blood cells, including the lymph nodes, spleen, thymus, and lymphoid tissue.

Those in blood banks work to keep blood supplies safe and accessible and may supervise labs that analyze blood samples and provide advice to organizations that provide advocacy services for patients with genetic blood disorders. These hematologists may also work with government agencies on education campaigns designed to inform the public of disorders, such as anemia.

As part of a patient care team, hematologists work closely with surgeons, radiation oncologists, and other specialists to help patients understand their diagnosis, develop individualized treatment plans, coordinate aspects of care, and provide surgical, chemotherapeutic, and immunotherapeutic treatment.

The work of hematologists is supported by laboratory technicians who examine samples of blood and blood-forming tissue, which provides information about abnormalities and issues identified in laboratory screening. A hematologist may also specialize in genetic testing if they focus on inherited blood conditions.

Hematologists working in laboratories are referred to as hematopathologists. These physicians work closely with hematologists to diagnose hematologic diseases. Working together, the hematologist and hematopathologist formulate a diagnosis and deliver appropriate therapy when needed.

Blood Diseases

Hematologists treat blood diseases and disorders. Examples include:

Hemophilia, coagulation disorders, and idiopathic thrombocytopenic purpura;
Hematologic malignancies, such as leukemia and lymphoma;
Hemoglobinopathies, such as sickle cell disease;
arterial thromboembolism; deep-vein thrombosis; and neutropenia.

Deep vein thrombosis (DVT) occurs when a blood clot forms in one or more deep veins in the body, usually in the legs, and can cause pain or swelling or occur with no symptoms. Pulmonary embolism occurs when the DVT clot breaks loose and travels through the bloodstream to the lungs, blocking blood flow. When DVT and pulmonary embolism occur together, it’s called venous thromboembolism (VTE).

Not only does a hematologist focus on the diagnosis, treatment, and prevention of blood diseases, but also on immunologic, hemostatic (blood clotting), and vascular systems.

Hematologic Testing

Hematologic tests aid in the diagnosis of blood diseases, such as anemia and certain cancers of the blood and inflammatory diseases, and can help monitor blood loss and infection.

An example of a hematologic test is a complete blood count (CBC). This test includes white blood cell count (WBC), red blood cell count (RBC), platelet count, hematocrit (HCT) red blood cell volume, hemoglobin (Hb) concentration, differential white blood count, and red blood cell indices.

Other examples of hematologic tests include prothrombin time (PT), partial thromboplastin time (PTT), and international normalized ratio (INR).