anemia

Definition

Anemia is a condition in which you don't have enough healthy red blood cells to carry adequate oxygen to your tissues. If you have anemia, you probably feel tired a lot. There are many forms of anemia, each with its own cause. Anemia can be temporary or long term, and it can range from mild to severe.

Symptoms
Signs and symptoms vary depending on the cause of your anemia, but may include:

• Fatigue
• Pale skin
• A fast or irregular heartbeat
• shortness of breath
• Chest pain
• Dizziness
• Cognitive problems
• Cold hands and feet
• Headache
  

Initially, anemia can be so mild it goes unnoticed. But signs and symptoms increase as anemia worsens.

Causes
There are more than 400 types of anemia, which are divided into 3 groupings:

• Anemia caused by blood loss
• Anemia caused by decreased or faulty red blood cell production
• Anemia caused by destruction of red blood cells

Anemia Caused by Blood Loss
Red blood cells can be lost through bleeding, which can occur slowly over a long period of time, and can often go undetected. This kind of chronic bleeding commonly results from the following:

• Gastrointestinal conditions such as ulcers, hemorrhoids, gastritis (inflammation of the stomach) and cancer.
• Use of nonsteroidal anti-inflammatory drugs (NSAIDS) such as aspirin or Motrin.
• Menstruation and childbirth in women, especially if menstrual bleeding is excessive and if there are multiple pregnancies.

Anemia Caused by Decreased or Faulty Red Blood Cell Production
The body may produce too few blood cells or the blood cells may not work properly. In either case, anemia can result. Red blood cells may be faulty or decreased due to abnormal red blood cells or the a lack of minerals and vitamins needed for red blood cells to work properly. Conditions associated with these causes of anemia include the following:

• Sickle cell anemia
• Iron deficiency anemia
• Vitamin deficiency
• Bone marrow and stem cell problems
• Other health conditions

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
• Hypothyroidism
• 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.

Risk Factors
These factors place you at increased risk of anemia:

• Poor diet: Anyone — young or old — whose diet is consistently low in iron and vitamins, especially folate, is at risk of anemia. Your body needs iron, protein and vitamins to produce sufficient numbers of red blood cells.
• Intestinal disorders: Having an intestinal disorder that affects the absorption of nutrients in your small intestine — such as Crohn's disease and celiac disease — puts you at risk of anemia.
• Surgical removal of or surgery to the parts of your small intestine where nutrients are absorbed can lead to nutrient deficiencies and anemia.
• Menstruation. In general, women are at greater risk of iron deficiency anemia than are men. That's because women lose blood — and with it, iron — each month during menstruation.
• Pregnancy. If you're pregnant, you're at an increased risk of iron deficiency anemia because your iron stores have to serve your increased blood volume as well as be a source of hemoglobin for your growing fetus.
• Chronic conditions. For example, if you have cancer, kidney or liver failure, or another chronic condition, you may be at risk of what's called anemia of chronic disease. These conditions can lead to a shortage of red blood cells. Slow, chronic blood loss from an ulcer or other source within your body can deplete your body's store of iron, leading to iron deficiency anemia.
• Family history. If your family has a history of an inherited anemia, such as sickle cell anemia, you also may be at increased risk of the condition.

Complications
Left untreated, anemia can cause numerous complications, such as:

• Severe fatigue. When anemia is severe enough, you may be so tired that you can't complete everyday tasks. You may be too exhausted to work or play.
• Heart problems. Anemia can lead to a rapid or irregular heartbeat — an arrhythmia. Your heart must pump more blood to compensate for the lack of oxygen in the blood when you're anemic. This can even lead to congestive heart failure.
• Nerve damage. Vitamin B-12 is essential not only for healthy red blood cell production, but also for healthy nerve function.
• Impaired mental function. A shortage of vitamin B-12 can also affect your mental abilities.
• Death. Some inherited anemias, such as sickle cell anemia, can be serious and lead to life-threatening complications. Losing a lot of blood quickly results in acute, severe anemia and can be fatal.

Treatment and drugs
Anemia treatment depends on the cause:

• Iron deficiency anemia. This form of anemia is treated with iron supplements, which you may need to take for several months or longer. If the underlying cause of iron deficiency is loss of blood — other than from menstruation — the source of the bleeding must be located and stopped. This may involve surgery.
• Vitamin deficiency anemias. Pernicious anemia is treated with injections — often lifetime injections — of vitamin B-12. Folic acid deficiency anemia is treated with folic acid supplements.
• Anemia of chronic disease. There's no specific treatment for this type of anemia. Doctors focus on treating the underlying disease. Iron supplements and vitamins generally don't help this type of anemia. However, if symptoms become severe, a blood transfusion or injections of synthetic erythropoietin, a hormone normally produced by your kidneys, may help stimulate red blood cell production and ease fatigue.
• Aplastic anemia. Treatment for this anemia may include blood transfusions to boost levels of red blood cells. You may need a bone marrow transplant if your bone marrow is diseased and can't make healthy blood cells. You may need immune-suppressing medications to lessen your immune system's response and give the transplanted bone marrow a chance to start functioning again.
• Anemias associated with bone marrow disease. Treatment of these various diseases can range from simple medication to chemotherapy to bone marrow transplantation.
• Hemolytic anemias. Managing hemolytic anemias includes avoiding suspect medications, treating related infections and taking drugs that suppress your immune system, which may be attacking your red blood cells. Short courses of treatment with steroids, immune suppressant medications or gamma globulin can help suppress your immune system's attack on your red blood cells.
  
• Sickle cell anemia. Treatment for this anemia may include the administration of oxygen, pain-relieving drugs, and oral and intravenous fluids to reduce pain and prevent complications. Doctors also commonly use blood transfusions, folic acid supplements and antibiotics. A bone marrow transplant may be an effective treatment in some circumstances. A cancer drug called hydroxyurea (Droxia, Hydrea) also is used to treat sickle cell anemia in adults.
  

Rujukan

1. http://www.webmd.com
2. http://www.mayoclinic.com