Anemia is more than just iron-poor blood, a widespread perception of this health condition. Anemia can result from a number of problems that reduce your blood's ability to transport oxygen.
There are several types of anemia, each with its own cause.
Iron-deficiency anemia. Your body isn't getting enough iron, is losing iron or isn't absorbing iron normally.
Megaloblastic anemia. Red blood cells don't mature normally and have a reduced capacity to carry oxygen.
Hemolytic anemia, including sickle cell disease. Red blood cells are destroyed faster than bone marrow can replace them.
Anemia is the most common blood disorder. It affects about 4 million Americans. In people younger than age 65, about six times as many women as men have anemia. However, this gender gap narrows to less than 2 to 1 in people older than age 65.
Although common, anemia can be a complex problem to diagnose and treat because of its many causes. If left untreated, the disorder may lead to serious illness.
Signs & Symptoms
Iron-deficiency anemia
This anemia is caused by a deficiency of iron. In older adults, iron deficiency usually results from chronic bleeding. In premenopausal women, iron-deficiency anemia typically results from excessive menstrual bleeding. A less common cause is too little iron in your diet. Rarely, surgical removal of your stomach or an intestinal disorder, such as celiac disease, can prevent adequate iron absorption. Mild anemia may cause no symptoms, or signs and symptoms may include:
Pale skin, gums, nail beds or eyelid linings
Fatigue
Rapid and forceful heartbeat
Megaloblastic anemia
Megaloblastic anemia can occur when red blood cells don't mature normally. The cells formed in bone marrow are enlarged, with a reduced capacity to carry oxygen. Abnormal bone marrow function (myelodysplastic syndromes), especially in elderly people, increasingly leads to megaloblastic anemia. Your body needs vitamin B-12 and folic acid, a B vitamin, for red blood cells to mature normally. When anemia is caused by a deficiency of B-12, it's called pernicious anemia. Usually, no signs and symptoms are apparent early in this disease, or signs and symptoms may include:
Reduced exercise endurance and rapid, forceful heartbeat
Sore tongue
Poor appetite, loss of weight
Disturbed gait and balance
Mental changes, including memory loss, depression and dementia
Numbness in hands and feet
Usually, no signs and symptoms are apparent early in folic acid deficiency anemia, or signs and symptoms may include:
Low exercise endurance and rapid heartbeat
Weight loss
Diarrhea
Hemolytic anemia
This is an uncommon anemia that develops when red blood cells are destroyed faster than bone marrow can replace them. The result is a shortage of red blood cells to transport oxygen. Early destruction can result from genetic defects or acquired defects.
Genetic defects in the red blood cell's physical or chemical makeup can lead to a rigid or elongated shape. The deformity causes red blood cells to become trapped in your spleen, where most are destroyed before the end of their normal lifespan. More commonly, defective hemoglobin causes red blood cells to develop a crescent (sickle) shape. Sickle cells lodge in small arteries, causing acute pain and blood clots. Sickle cell anemia most often affects blacks of African-American descent and Hispanic Americans.
Signs and symptoms of sickle cell disease:
Fatigue, breathlessness and rapid heartbeat
Delayed growth and development
Susceptibility to infections
Skin ulcers on the lower legs
Vision problems
Attacks of pain caused by blocked blood vessels and damaged organs
Aplastic crises, in which the number of red blood cells decreases drastically
In an emergency, severe shortness of breath, fatigue, light-headedness, particularly on standing
Acquired defects can occur when some infections or use of antibiotics or anti-inflammatory drugs break down red blood cells. Occasionally, you may acquire a mild form of anemia through an autoimmune process (reaction of the body against its own tissues perceived as foreign substances, resulting in the production of antibodies). Some artificial heart valves also increase the risk of red blood cell destruction by directly injuring cells.
Signs and symptoms of hemolytic anemia:
Fatigue, breathlessness and rapid heartbeat
Paleness
Yellow-tinged skin
Dark urine
Enlarged spleen
Sudden onset of pain in the upper abdomen
Risk Factors
Iron-deficiency anemia
These groups of people are most at risk:
Women of child-bearing age. In nonpregnant women, excessive menstrual bleeding may cause anemia. In pregnant women, a growing fetus may deplete the body's stores of iron.
Growing infants, children and adolescents. Growth spurts require increased amounts of iron.
Children who have lead poisoning.
Adults who experience blood loss from their digestive tract. This blood loss can occur through a variety of factors: use of aspirin and nonsteroidal anti-inflammatory drugs, a tumor in the colon or an ulcer in the esophagus, stomach or duodenum.
Megaloblastic anemia
In pernicious anemia, the basis of the deficiency of vitamin B-12 often is hereditary. People of northern European ancestry are at a higher risk.
Folic acid deficiency anemia occurs often in alcoholics. When alcohol is the primary source of calories, poor absorption of nutrients and malnutrition can occur. Pregnant or breast-feeding women may be at a higher risk if they aren't taking in enough folic acid for their body's higher demands. Infants and adolescents also need more folic acid during growth spurts, and the demand may outrun the supply. Certain anticonvulsant drugs and other medications may increase the risk of folic acid deficiency.
Hemolytic anemia
Inherited defects — such as occurs in sickle cell disease, which affects mostly blacks of African-American descent — can cause red blood cells to break down.
Medications, such as anti-inflammatory drugs or antibiotics, and autoimmune illnesses or infections may increase the risk of destruction of red blood cells.
Screening & Diagnosis
Iron-deficiency anemia
Your doctor may order blood tests to detect the size of your red blood cells and the amount of hemoglobin in the blood. When there is a question of blood loss from the digestive tract, you may undergo tests to detect blood in your stool.
Megaloblastic anemia
When a deficiency of vitamin B-12 is suspected, your doctor may order a blood test to measure the amount of vitamin B-12 in your blood and may examine a sample of your blood under a microscope to determine the size and shape of your red blood cells. Your doctor also may study a sample of your bone marrow. You may undergo a test to determine if intrinsic factor is present. Intrinsic factor is made by cells lining your stomach and is essential to absorb vitamin B-12. A Schilling test can determine if a deficiency of vitamin B-12 is due to lack of intrinsic factor or a failure to absorb the vitamin for some other reason.
When the anemia may be caused by folic acid deficiency, your doctor may advise blood tests to count the cells in your blood, to examine your cells under a microscope and to measure the amount of folic acid in your blood.
Hemolytic anemia
You may need to undergo blood tests, to check the number of young red blood cells and to see if the red blood cells are deformed. If you have hemolytic anemia, you'll have a higher number of young red blood cells than normal. One of the tests isolates and identifies the abnormal hemoglobin S, responsible for the sickle shape of the defective red blood cells in sickle cell disease. An enlarged spleen also raises a question of hemolytic anemia.
Treatment
Iron-deficiency anemia
Treating the anemia involves locating and stopping the bleeding. If the source can't be found or is menstrual, periodic iron supplements — either orally, or intravenously for people with absorption problems — help build up depleted stores. Your doctor may recommend surgery if you have an iron deficiency due to a loss of blood from your digestive tract, such as is the case with colon cancer. If anemia is severe, a transfusion of packed blood cells can immediately restore normal levels of red blood cells.
Megaloblastic anemia
Lifelong injections of vitamin B-12 correct pernicious anemia.
Treatment of folic acid deficiency involves eating a healthful diet and talking folic acid supplements as prescribed.
Hemolytic anemia
If you have sickle cell disease, your doctor may prescribe oral supplements of folic acid because sickle cell anemia increases your body's need for folic acid. Hydroxyurea, a drug used to treat other blood disorders, may help reduce the recurrence of acute attacks (crises). During an attack, your doctor may also administer pain relievers, fluid to prevent dehydration or oxygen to boost the level in your bloodstream. Your doctor also may prescribe antibiotics to deal with or prevent infections associated with sickle cell anemia. Blood transfusions may reduce your body's level of abnormal hemoglobin. If the anemia is the result of autoimmunity (reaction of your body to its own tissues perceived as foreign substances, resulting in production of antibodies), managing your condition may include avoiding suspect medications, treating related infections and taking immunosuppressive drugs, such as corticosteroids. Sometimes, removing your spleen is needed.