Blood disorders can affect any of the components of blood, including red blood cells, white blood cells, platelets, and clotting factors. Blood disorders can also affect the bone marrow, where immature cells called stem cells develop into the specialized cells of blood.
Each component of blood has unique functions. Red blood cells carry oxygen to the body’s tissues and take carbon dioxide away from tissues. White blood cells help fight infection and cancer. Platelets and clotting factors help the blood to clot, preventing both excessive bleeding and excessive clotting. Problems in the production or functioning of any of these specialized elements of blood can result in a variety of problems.
Here are some of the most common disorders affecting the blood:
A disorder in which the red blood cells do not provide enough oxygen to the body’s tissues, resulting in fatigue and other symptoms such as weakness, pale skin, rapid heartbeat, shortness of breath, dizziness, and numb or cold hands or feet. There are many types of anemia, each with its own cause. Some are associated with low production of red blood cells and others are related to an increased breakdown of red blood cells. Anemia can be temporary or chronic, and it can range from mild to severe.
- Iron deficiency anemia
A decrease in the number of red blood cells caused by too little iron, an element that is needed to make hemoglobin. Iron deficiency anemia is the most common type of anemia, especially among women. Causes include an iron-poor diet, poor absorption of iron by the body, and loss of blood due to heavy menstrual bleeding, ulcers, or other causes.
- Vitamin deficiency anemia
Anemia caused by inadequate levels of folic acid or vitamin B-12, two B vitamins that are needed to form healthy red blood cells. Pernicious anemia is a type of vitamin B-12 deficiency anemia caused by low levels of intrinsic factor, a protein produced in the gastrointestinal tract that is needed to absorb vitamin B-12 from the stomach.
- Sickle cell anemia
An inherited disease in which the red blood cells are abnormally shaped. These misshapen red blood cells die prematurely, causing a chronic shortage of red blood cells. They can also cause small blood clots and recurrent painful episodes called sickle cell pain crises. Continuous treatment is necessary to manage and control symptoms and to try to limit the frequency of crises.
- Aplastic anemia
A rare, life-threatening anemia caused by a decline in the bone marrow’s ability to produce all three types of blood cells (red blood cells, white blood cells, and platelets). Aplastic anemia may be caused by exposure to toxins, radiation, chemotherapy, some medications, and certain viral infections. Depending on the cause, it may be a temporary condition or a chronic disease.
- Hemolytic anemia
An anemia that occurs when red blood cells are destroyed faster than the bone marrow can replace them. Hemolytic anemia may be caused by an inherited illness or defect, an autoimmune disease such as lupus, an infection such as hepatitis, or certain medications such as antibiotics. In some cases it has no known cause.
A disorder that interferes with iron metabolism and results in excess iron deposits throughout the body. The accumulation of iron can cause liver disease, heart failure, diabetes, arthritis, and other serious problems. Hemochromatosis is one of the most common inherited blood disorders. It is treated by removing blood from the body to reduce iron stores.
A rare inherited bleeding disorder in which the blood does not clot normally due to absent or low levels of proteins called clotting factors. Severe hemophilia is usually diagnosed in the first year of life, but milder disease may not be diagnosed until adulthood. Hemophilia is treated with infusions or injections of clotting factors to prevent bleeding or to stop bleeding when it occurs.
A condition in which stem cells produced in the bone marrow fail to mature normally into red blood cells, white blood cells, and platelets. The immature blood cells do not work the way they should and die prematurely. Myelodysplastic syndrome is more common among older adults. In most cases, the cause is unknown. Treatment depends on the clinical situation.
A condition in which a greater than normal number of stem cells produced in the bone marrow develop into one or more types of blood cells and the total number of blood cells slowly increases. There are several types of myeloproliferative disorders, depending on the type of cell or tissue that is increasing excessively.
An abnormally low number of neutrophils, a type of white blood cell that helps fight bacterial infections. Neutropenia is not a disease but a sign of an underlying problem, such as a bacterial or viral infection, leukemia, aplastic anemia, or a medication side effect. Treatment involves addressing the underlying cause.
An inherited disease characterized by defective production of hemoglobin, the oxygen-carrying component of blood cells. Severe thalassemia requires regular blood transfusions and folate supplements. Because frequent blood transfusions can result in iron overload, chelation therapy may also be necessary to prevent iron-induced damage to the heart, liver, and other organs.
A blood disorder in which there are not enough platelets, the cells in the blood that help blood to clot. A low platelet count can occur due to low production of platelets in the bone marrow or increased breakdown of platelets in the bloodstream, spleen, or liver. Treatment depends on the cause of the condition.