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What Causes Anemia? continued... Sickle cell anemia is an inherited disorder that affects African-Americans. Red blood cells become crescent-shaped because of a genetic defect. They break down rapidly, so oxygen does not get to the body's organs, causing anemia. The crescent-shaped red blood cells also get stuck in tiny blood vessels, causing pain. Iron deficiency anemia occurs because of a lack of the mineral iron in the body. Bone marrow in the center of the bone needs iron to make hemoglobin, the part of the red blood cell that transports oxygen to the body's organs. Without adequate iron, the body cannot produce enough hemoglobin for red blood cells. The result is iron deficiency anemia. Iron deficiency anemia can be caused by the following: - An iron-poor diet, especially in infants, children, teens and vegetarians
- The metabolic demands of pregnancy and breastfeeding that deplete a woman's iron stores
- Menstruation
- Frequent blood donation
- Endurance training
- Digestive conditions such as Crohn's disease or surgical removal of part of the stomach or small intestine
- Certain drugs, foods, and caffeinated drinks
Vitamin deficiency anemia may occur when vitamin B-12 and folate are deficient. These two vitamins are needed to make red blood cells. Conditions leading to anemia caused by vitamin deficiency include the following: - Megaloblastic anemia: Vitamin B-12 or folate or both are deficient
- Pernicious anemia: Poor vitamin B-12 absorption caused by conditions such as Crohn's disease, an intestinal parasite infection, surgical removal of part of the stomach or intestine, or infection with HIV
- Dietary deficiency: Eating little or no meat may cause a lack vitamin B12, while overcooking or eating too few vegetables may cause a folate dificiency
- Other causes of vitamin deficiency: pregnancy, certain medications, alcohol abuse, intestinal diseases such as tropical sprue and gluten-sensitive enteropathy (celiac disease)
During early pregnancy, sufficient folic acid can prevent the fetus from developing neural tube defects such as spina bifida. Bone marrow and stem cell problems may prevent the body from producing enough red blood cells. Some of the stem cells found in bone marrow develop into red blood cells. If stem cells are too few, defective, or replaced by other cells such as metastatic cancer cells, anemia may result. Anemia resulting from bone marrow or stem cell problems include the following: - Aplastic anemia occurs when there's a marked reduction in the number of stem cells or absence of these cells. Aplastic anemia can be inherited, can occur without apparent cause, or can occur when the bone marrow is injured by medications, radiation, chemotherapy, or infection.
- Thalassemia occurs when the red cells can't mature and grow properly. Thalassemia is an inherited condition that typically affects people of Mediterranean, African, Middle Eastern, and Southeast Asian descent. This condition can range in severity from mild to life-threatening; the most severe form is called Cooley's anemia.
- Lead exposure is toxic to the bone marrow, leading to fewer red blood cells. Lead poisoning occurs in adults from work-related exposure and in children who eat paint chips. Improperly glazed pottery can also taint food and liquids with lead.
Anemia associated with other conditions usually occur when there are too few hormones necessary for red blood cell production. Conditions causing this type of anemia include the following: - Advanced kidney disease
- Hypothroidism
- Other chronic diseases – examples include cancer, infection, and autoimmune disorders such as lupus or rheumatoid arthritis
Anemia Caused by Destruction of Red Blood Cells When red blood cells are fragile and cannot withstand the routine stress of the circulatory system, they may rupture prematurely, causing hemolytic anemia. Hemolytic anemia can be present at birth or develop later. Sometimes there is no known cause (spontaneous). Known causes of hemolytic anemia may include any of the following: - Inherited conditions, such as sickle cell anemia and thalassemia
- Stressors such as infections, drugs, snake or spider venom, or certain foods
- Toxins from advanced liver or kidney disease
- Inappropriate attack by the immune system (called hemolytic disease of the newborn when it occurs in the fetus of a pregnant woman)
- Vascular grafts, prosthetic heart valves, tumors, severe burns, chemical exposure, severe hypertension, and clotting disorders
- In rare cases, an enlarged spleen can trap red blood cells and destroy them before their circulating time is up
VitaDocs Medical Reference
SOURCES: American Academy of Family Physicians. The American Medical Athletic Association. Albemarle Pulmonary Medical Associates, PA. Gary W. Tamkin, MD, Attending Physician, Highland General Hospital - Alameda County Medical Center, Oakland. Cornell University Department of Animal Science Reviewed by Joseph C. Alvarnas, MD on July 19, 2007 © 2007 VitaDocs.com All rights reserved.
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