What Is Anemia?
Anemia (uh-NEE-me-uh) is a condition in which your blood has a lower than normal number of red blood cells.
Anemia also can occur if your red blood cells don’t contain enough hemoglobin (HEE-muh-glow-bin). Hemoglobin is an iron-rich protein that gives blood its red color. This protein helps red blood cells carry oxygen from the lungs to the rest of the body.
If you have anemia, your body doesn’t get enough oxygen-rich blood. As a result, you may feel tired or weak. You also may have other symptoms, such as shortness of breath, dizziness, or headaches.
Severe or long-lasting anemia can damage your heart, brain, and other organs in your body. Very severe anemia may even cause death.
Overview
Blood is made up of many parts, including red blood cells, white blood cells, platelets (PLATE-lets), and plasma (the fluid portion of blood).
Red blood cells are disc-shaped and look like doughnuts without holes in the center. They carry oxygen and remove carbon dioxide (a waste product) from your body. These cells are made in the bone marrow-a sponge-like tissue inside the bones.
White blood cells and platelets (PLATE-lets) also are made in the bone marrow. White blood cells help fight infection. Platelets stick together to seal small cuts or breaks on the blood vessel walls and stop bleeding. With some types of anemia, you may have low numbers of all three types of blood cells.
Anemia has three main causes: blood loss, lack of red blood cell production, or high rates of red blood cell destruction. These causes might be the result of diseases, conditions, or other factors.
Outlook
Many types of anemia can be mild, short term, and easily treated. You can even prevent some types with a healthy diet. Other types can be treated with dietary supplements.
However, certain types of anemia can be severe, long lasting, and even life threatening if not diagnosed and treated.
If you have signs or symptoms of anemia, see your doctor to find out whether you have the condition. Treatment will depend on the cause of the anemia and how severe it is.
More information
The three main causes of anemia are:
- Blood loss
- Lack of red blood cell production
- High rates of red blood cell destruction
For some people, the condition is caused by more than one of these factors.
Blood Loss
Blood loss is the most common cause of anemia, especially iron-deficiency anemia. Blood loss can be short term or persist over time.
Heavy menstrual periods or bleeding in the digestive or urinary tract can cause blood loss. Surgery, trauma, or cancer also can cause blood loss.
If a lot of blood is lost, the body may lose enough red blood cells to cause anemia.
Lack of Red Blood Cell Production
Both acquired and inherited conditions and factors can prevent your body from making enough red blood cells. “Acquired” means you aren’t born with the condition, but you develop it. “Inherited” means your parents passed the gene for the condition on to you.
Acquired conditions and factors that can lead to anemia include poor diet, abnormal hormone levels, some chronic (ongoing) diseases, and pregnancy.
Diet
A diet that lacks iron, folic acid (folate), or vitamin B12 can prevent your body from making enough red blood cells. Your body also needs small amounts of vitamin C, riboflavin, and copper to make red blood cells.
Conditions that make it hard for your body to absorb nutrients also can prevent your body from making enough red blood cells.
Hormones
Your body needs the hormone erythropoietin (eh-rith-ro-POY-eh-tin) to make red blood cells. This hormone stimulates the bone marrow to make these cells. A low level of this hormone can lead to anemia.
Diseases and Disease Treatments
Chronic diseases, like kidney disease and cancer, can make it hard for your body to make enough red blood cells.
Some cancer treatments may damage the bone marrow or damage the red blood cells’ ability to carry oxygen. If the bone marrow is damaged, it can’t make red blood cells fast enough to replace the ones that die or are destroyed.
People who have HIV/AIDS may develop anemia due to infections or medicines used to treat their diseases.
Pregnancy
Anemia can occur during pregnancy due to low levels of iron and folic acid and changes in the blood.
During the first 6 months of pregnancy, the fluid portion of a woman’s blood (the plasma) increases faster than the number of red blood cells. This dilutes the blood and can lead to anemia.
Aplastic Anemia
Some infants are born without the ability to make enough red blood cells. This condition is called aplastic anemia. Infants and children who have aplastic anemia often need blood transfusions to increase the number of red blood cells in their blood.
Acquired conditions or factors, such as certain medicines, toxins, and infectious diseases, also can cause aplastic anemia.
High Rates of Red Blood Cell Destruction
Both acquired and inherited conditions and factors can cause your body to destroy too many red blood cells. One example of an acquired condition is an enlarged or diseased spleen.
The spleen is an organ that removes wornout red blood cells from the body. If the spleen is enlarged or diseased, it may remove more red blood cells than normal, causing anemia.
Examples of inherited conditions that can cause your body to destroy too many red blood cells include sickle cell anemia, thalassemias, and lack of certain enzymes. These conditions create defects in the red blood cells that cause them to die faster than healthy red blood cells.
Hemolytic anemia is another example of a condition in which your body destroys too many red blood cells. Inherited or acquired conditions or factors can cause hemolytic anemia. Examples include immune disorders, infections, certain medicines, or reactions to blood transfusions.