Hematology is the study of diseases related to the blood, including diagnosis, pathology, treatment, prevention, and prognosis. There are a variety of diseases under the hematology umbrella—including anemia, bleeding disorders (hemophilia, blood clots, Von Willebrand disease), and blood cancers (leukemia, lymphoma, multiple myeloma).
The blood is made up of different components, and different diseases of the blood are associated with these different components.
Red Blood Cells
Red blood cells transport fresh oxygen throughout your body. They are created in the bone marrow and have a typical lifespan of about four months.
Red blood cell disorders include:
What is Anemia?
Patients with anemia do not have enough red blood cells for oxygen to travel throughout the body. There are several types of anemia, ranging in timespan and severity, and different things may cause the disease. According to Mayo Clinic, general symptoms of anemia may include:
- Pale/yellowing skin
- Irregular heartbeat
- Shortness of breath
- Chest pain
- Cold hands/feet
Degree of symptoms may also vary from person to person, and could also change overtime.
is also characterized by fewer red blood cells than normal as well as less hemoglobin. Thalassemia may cause anemia, so some thalassemia symptoms overlap those of anemia, such as fatigue, weakness, and pale/yellowing skin. Other signs of thalassemia may include facial bone deformities, slow growth, abdominal swelling, and dark urine.
Unlike anemia and thalassemia, polycythemia, a rare blood disorder, manifests in the presence of too many red blood cells. This restricts blood flow because the blood becomes too thick. In primary polycythemia, the increased red blood cell count is biological due to something in the patient’s body, but in secondary polycythemia, oxygen cannot easily make its way through the body due to other causes like smoking or congenital heart disease. Polycythemia shares some symptoms with other red blood diseases, including fatigue, shortness of breath, headache, and dizziness; according to the Dana-Farber Cancer Institute, additional symptoms may include:
- Deep reddish-purple coloring
- Poor feeding
- Low blood sugar
- Itchiness, notably after a warm bath/shower
- Numbness/tingling/burning/weakness in the hands/feet/arms/legs
White Blood Cells
Although they only constitute a small part of the overall composition of the blood, white blood cells are important because they defend the body from viruses, bacteria, and other disease-causing culprits. Like their red counterparts, white blood cells are also made in the bone marrow, but they only have a lifespan of one to three days. White blood cells include monocytes, lymphocytes, neutrophils, basophils, and eosinophils.
White blood cell disorders include
Lymphoma is classified by two main types: Hodgkin’s lymphoma and non-Hodgkin’s lymphoma. Patients with Hodgkin’s lymphoma (previously called Hodgkin’s disease) have abnormal growth in their lymphatic system cells. Hodgkin’s lymphoma symptoms may include:
- Swelling (but no pain) in the lymph nodes of the neck/armpits/groin
- Night sweats
- Unexplained weight loss
- Alcohol sensitivity, or lymph node pain after alcohol consumption
In non-Hodgkin’s lymphoma, which is more common that Hodgkin’s lymphoma, tumors manifest from lymphocytes. Non-Hodgkin’s lymphoma shares many symptoms with Hodgkin’s lymphoma, including swollen lymph nodes without pain, fatigue, fever, night sweats, and unexplained weight loss; additional symptoms may include abdominal pain or swelling and chest pain, coughing, and difficulty breathing.
Although leukemia could, in some cases, affect other blood cells, it is most commonly associated with an overproduction of abnormal white blood cells that cannot fight off infection the way healthy white blood cells do. Leukemia may have similar symptoms as lymphoma, including swollen lymph nodes, unexplained weight loss, fatigue, and night sweats, as well as other symptoms such as:
- Bruising/bleeding easily
- Susceptibility to infection
- Discomfort beneath left lower ribs
Platelets are the blood cells that are responsible for forming clots to prevent bleeding. When a blood vessel is damaged, the platelets are made aware. When they arrive the platelets stick together—forming a clot—to help heal the injury, as well as signal more platelets to come help finish the job. Platelets are made in the bone marrow. Abnormal platelet counts—high or low—could result in conditions including thrombocytopenia and thrombocytosis. A healthy adult platelet count could be anywhere from 150,000 to 450,000 platelets per microliter of blood. Risks become significant when platelet counts fall below 20,000 and 10,000; a count under 50,000 could cause mild bleeding issues.
Thrombocytopenia occurs when the body has an unusually low platelet count—below 150,000 platelets per microliter of blood. The disease could be mild or moderate in severity and span anywhere from a few days to years. According to the National Heart, Lung, and Blood Institute, the disease often has no symptoms at all and is only discovered through routine blood testing. Signs of bleeding—internally or externally—are the major symptoms of the disease. External bleeding is often the first symptom of the disease and could also lead to purpura—purple, brown, and red bruises—and petechiae—red or purple dots—on the skin.
Unlike thrombocytopenia, a condition called thrombocytosis occurs when the body produces too many platelets. Often, there is an underlying cause, like an infection—in this case, the condition is referred to as reactive thrombocytosis or secondary thrombocytosis. In more rare instances, there is no clear cause, and the disease is then referred to as primary thrombocythemia or essential thrombocythemia. Just as in thrombocytopenia, there are often no signs or symptoms of the disease—if symptoms occur, they often pertain to the underlying cause of the condition. Possible symptoms may be similar to those of other bleeding disorders, including:
- Chest pain
- Numbness/tingling in hands/feet
Plasma, which makes up the majority of the blood, is responsible for bringing vital components of the blood—such as nutrients, protein, and hormones—throughout the body. Not only does it help transport what the body needs; it also eliminates harmful waste from the body.
Plasma disorders are rare, but one of them is multiple myeloma, a cancer of the plasma cells. In patients with multiple myeloma, the plasma cells become cancerous, and their growth overpowers that of healthy cells. Healthy plasma cells make antibodies called immunoglobulins, which help defend the body from germs, but cancerous plasma cells make abnormal antibodies. Because multiple myeloma patients have an overabundance of cancerous cells, they have fewer healthy cells, which could cause anemia or thrombocytopenia. In its early stages, multiple myeloma could display no symptoms at all, and may only be discovered through routine or unrelated check-ups. When they do present, symptoms of multiple myeloma include:
- Bone pain usually in the back/ribs
- Unexplained fractures, usually in the spine
- Recurring infections
- Shortness of breath
- Unexplained weight loss
- Increased thirst/urination
Sources: Mayo Clinic; Cancer Treatment Centers of America; National Heart, Lung, and Blood Institute; Dana-Farber Cancer Institute; American Society of Hematology; Healthline; University of Rochester Medical Center; American Cancer Society