A hematologist is a medical doctor who specializes in conditions affecting blood, bone marrow, and the lymphatic system. This medical professional diagnoses, manages, and treats a range of disorders, which can be either noncancerous or cancerous.
A Hematologist’s Scope
A hematologist’s expertise covers the components of blood, including red blood cells, white blood cells, and platelets. They also focus on the bone marrow, which is the spongy tissue inside bones responsible for producing these blood cells through a process called hematopoiesis. The lymphatic system, comprising lymph nodes, spleen, and thymus, falls within their purview, as it plays a role in immunity and fluid balance.
Conditions Related to Blood Cell Abnormalities
Hematologists frequently diagnose conditions stemming from irregularities in blood cell production or function. Anemias, characterized by insufficient red blood cells or hemoglobin, are common examples. These include iron deficiency anemia, aplastic anemia (where the bone marrow doesn’t produce enough new blood cells), and hemolytic anemia (involving premature red blood cell destruction).
Blood cancers also fall within this specialization, including:
- Leukemia: Involves the overproduction of abnormal white blood cells in the bone marrow.
- Lymphoma: Affects the lymphatic system, leading to abnormal cell growth in lymph nodes and other lymphatic tissues.
- Multiple myeloma: A cancer of plasma cells, a type of white blood cell, that accumulates in the bone marrow.
- Myelodysplastic syndromes (MDS): Disorders where the bone marrow produces abnormal or immature blood cells, leading to low blood counts.
- Myeloproliferative neoplasms (MPN): Involve the overproduction of one or more types of blood cells (red blood cells, white blood cells, or platelets) originating from a mutated stem cell in the bone marrow.
Bleeding and Clotting Disorders
Hematologists also manage disorders that affect the blood’s ability to clot, either excessively or insufficiently. Bleeding disorders occur when the blood cannot properly form clots, leading to prolonged or excessive bleeding. Hemophilia is a rare inherited bleeding disorder where specific clotting factors, typically Factor VIII or IX, are deficient or absent, preventing proper clot formation. Von Willebrand disease is another common inherited bleeding disorder, caused by a deficiency or dysfunction of von Willebrand factor, a protein that helps platelets adhere to injured blood vessels. Thrombocytopenia involves abnormally low platelet counts, which impairs the blood’s ability to clot effectively.
Conversely, clotting disorders involve an increased tendency for blood to form clots, potentially blocking blood flow. Deep vein thrombosis (DVT) is a condition where blood clots form in deep veins, often in the legs, which can lead to pain and swelling. A pulmonary embolism (PE) occurs when a DVT clot breaks off and travels to the lungs, blocking a pulmonary artery. Thrombophilia refers to a group of disorders that increase the risk of developing abnormal blood clots, often due to genetic factors like Factor V Leiden mutation or acquired conditions like antiphospholipid antibody syndrome.
How Hematologists Investigate Conditions
Hematologists utilize various diagnostic tools to investigate blood-related conditions. A complete blood count (CBC) is a routine test that measures the number of red blood cells, white blood cells, and platelets, as well as hemoglobin and hematocrit levels. A peripheral blood smear involves examining a blood sample under a microscope to assess the size, shape, and appearance of blood cells, which can reveal abnormalities.
For conditions affecting the bone marrow, a bone marrow biopsy and aspiration may be performed. This procedure involves taking a small sample of liquid marrow (aspiration) and solid bone marrow tissue (biopsy), typically from the hip bone, for microscopic analysis. Coagulation tests, such as prothrombin time (PT) and partial thromboplastin time (PTT), measure how long it takes for blood to clot, helping to identify bleeding or clotting disorders. Genetic testing is also employed to detect inherited or acquired genetic changes that can cause various hematologic disorders, including certain cancers.
When to Consult a Hematologist
A referral to a hematologist is typically made when a primary care physician suspects an underlying blood, bone marrow, or lymphatic system disorder. Common symptoms that might prompt such a referral include persistent unexplained fatigue or weakness, which can indicate anemia or other blood count issues. Easy bruising or bleeding, such as frequent nosebleeds or heavy menstrual bleeding, suggests a potential bleeding disorder.
Recurrent or severe infections may point to problems with white blood cell production or function. Swollen lymph nodes, an enlarged spleen, or unexplained weight loss are also signs that could warrant a hematology evaluation, as these can be symptoms of blood cancers like lymphoma or leukemia. Abnormal results from routine blood tests, such as unusually high or low red blood cell, white blood cell, or platelet counts, often lead to a hematologist consultation.