Anemia is caused by three main factors: blood loss, low red blood cell production, and red blood cell destruction.
1. Blood loss
2. Low red blood cell production
Dietary deficiencies of iron, folic acid, protein, vitamin B12, and vitamin C can cause anemia. Anemia is also common during pregnancy, as more red blood cells are needed for the growing fetus. Chronic diseases may also hinder red blood cell production, such as kidney diseases, arthritis, diabetes, and cancer.
3. Red blood cell destruction
Since red blood cells have a four-month lifespan, the body must continue to produce new ones. However, red blood cells can be destroyed early due to conditions such as sickle cell anemia and thalassemia. Medical treatment such as chemotherapy can also kill red blood cells due to complex reactions between the drugs and red blood cell proteins.
What are common types of anemia?
- Iron-deficiency anemia: Iron-deficiency anemia occurs when your body does not have enough iron, due to either blood loss or poor iron absorption. Risk factors for iron-deficiency anemia include pregnancy, childbirth, and gastric bypass surgery for weight loss.
- Pernicious anemia: Pernicious anemia is caused by low levels of vitamin B12 or folate (folic acid), often due to insufficient consumption of these nutrients via diet. In some cases, low vitamin B12 and folate levels can occur due to parasitic infestation, medications, acidity, or an autoimmune disorder that prevents the vitamin from being absorbed in the gastrointestinal tract.
- Aplastic anemia: Aplastic anemia is a rare condition in which the bone marrow stops producing enough blood cells (red blood cells, white blood cells, and platelets). This occurs when blood-forming stem cells in bone marrow are destroyed or depleted, especially when the immune system attacks the stem cells. Aplastic anemia can also be caused by viral infections, ionizing radiation, or exposure to harmful chemicals or drugs.
- Hemolytic anemia: Hemolytic anemia occurs when red blood cells are broken down in the bloodstream or the spleen. Causes include leaky heart valves, aneurysm, infections, autoimmune diseases, or congenital defects that affect the shape and function of red blood cells. Examples of inherited hemolytic anemias include thalassemia and low levels of enzymes such as glucose-6 phosphate dehydrogenase.
- Sickle cell anemia: Sickle cell anemia is hereditary hemolytic anemia in which the hemoglobin protein is defective, resulting in stiff red blood cells that block circulation due to their inability to move through small blood capillaries.
- Other disorders: Other conditions can cause anemia by impairing the body's ability to produce red blood cells. For example, people with kidney disease may suffer from anemia because their kidneys do not produce enough erythropoietin, a hormone that signals the bone marrow to create new or more red blood cells.
How is anemia treated?
Managing anemia involves treating the underlying cause and may include:
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Maakaron JE. Anemia. Medscape. https://emedicine.medscape.com/article/198475-overview
National Institutes of Health. In Brief: Your Guide to Anemia. https://www.nhlbi.nih.gov/files/docs/public/blood/anemia-inbrief_yg.pdf
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