Anemia

Overview

Anemia develops when your blood has a lower-than-normal amount of healthy red blood cells or hemoglobin. Hemoglobin is an iron-rich protein that helps red blood cells carry oxygen from the lungs to the rest of the body.

When you have anemia, your body does not get enough oxygen-rich blood. This can make you feel tired or weak. Some types last a long time and may never go away completely.

Related Terms

Anemia goes by several other names depending on its type:

• Iron-deficiency anemia occurs when a lack of iron reduces the body’s ability to produce hemoglobin. It is the most common type of anemia.
• Pernicious anemia is caused by a problem with the body not being able to absorb vitamin B12, which prevents the body from creating enough healthy red blood cells. Cobalamin is another name for vitamin B12, so this type of anemia can also be called cobalamin deficiency.
• Hemolytic anemia is caused by red blood cell destruction.
• Aplastic anemia is caused by the bone marrow (an area within the bones) not being able to make new blood cells.
• Macrocytic anemia or megaloblastic anemia occurs when the bone marrow produces abnormally large red blood cells. This is usually due to a nutritional deficiency like a lack of vitamin B12 or folate.

Signs and Symptoms

Symptoms of anemia can be mild or severe. They depend on how serious the anemia is and how quickly it develops. Mild anemia is common and treatable. If you have mild anemia, you may have no symptoms at all. Other types are serious and need prompt treatment. Some rare anemias, such as severe aplastic anemia, can be fatal if left untreated.

Mild anemia may cause:

• Tiredness or weakness
• Pale or yellowish skin

Moderate anemia may cause:

• Faintness or dizziness
• Increased thirst
• Sweating
• Weak and rapid pulse
• Fast breathing

Severe anemia may cause:

• Lower leg cramps while exercising
• Shortness of breath
• Abnormal heart rhythms, called arrhythmias
• Heart murmur (an extra or unusual sound heard during a heartbeat)
• Enlarged heart
• Heart failure
• Sadness, low energy, and changing moods

Iron-deficiency anemia may also cause:

• Pale skin
• Chest pain
• Coldness in the hands and feet
• Difficulty concentrating
• Pica (an unusual craving for non-food items such as ice, dirt, paint, or starch)
• Restless legs syndrome

Vitamin B12 deficiency can cause:

• Tingling and numbness in the hands and feet
• Smooth tongue
• Muscle weakness and loss of reflexes
• Trouble walking or keeping balance
• Confusion, dementia, depression, or memory loss in severe cases

Related Health Effects

Untreated anemia can lead to serious health problems. If left untreated, anemia can raise your risk of:

• Heart problems, including an irregular heartbeat, a larger than normal heart, and heart failure
• Infections
• Pregnancy complications

Anemia can also make other health conditions worse. In children, severe anemia can cause developmental delays. This means that the child does not reach some developmental milestones as early as healthy children.

Severe or long-lasting pernicious anemia can damage the heart and nervous system. People who have pernicious anemia may also be at higher risk for stomach cancer.

Serious or untreated anemia in pregnancy can cause:

• Preterm labor
• Low birthweight
• Anemia and developmental delays in the baby

Causes and Risk Factors

Anemia can affect people of all ages, races, and ethnicities. It has three main causes: 

• Your body does not make enough red blood cells. To make healthy red blood cells, your body needs iron, vitamin B12, folate (another B vitamin), small amounts of other vitamins and minerals, and protein. Your body also needs a hormone called erythropoietin, which boosts red blood cell production. Certain chronic diseases — such as cancer, HIV/AIDS, rheumatoid arthritis, and kidney disease — can harm the body’s ability to make enough red blood cells.
• Your body destroys too many red blood cells. Red blood cells normally live about 120 days. Sometimes the body destroys them too soon through a process called hemolysis. This can be caused by an infection, an inherited condition, or an autoimmune disorder.
• Your body loses too many red blood cells. Blood loss leads to low levels of iron. Without enough iron, the body makes fewer red blood cells. Causes of blood loss include inflammation of the esophagus, stomach, intestines or colon, injuries, surgery, heavy menstrual periods, and certain cancers.

Other common conditions that can lead to anemia include:

• Pregnancy
• Inflammation of the gastrointestinal tract (esophagus, stomach, intestines, colon)
• Colon polyps or colon cancer
• Ulcers
• Inherited blood disorders such as sickle cell disease and thalassemia

Risk factors that increase your chances of developing anemia include:

• Age: Your chances of developing anemia increase as you age.
• Family history: Some types of anemia are inherited.
• Other health conditions: Chronic kidney disease, cancer, and autoimmune diseases can cause your body to make fewer red blood cells.
• Certain medicines or treatments: Chemotherapy and radiation therapy for cancer can raise your risk.
• Diet: Not getting enough iron, vitamin B12, or folic acid raises your risk.
• Alcohol use: Drinking too much alcohol raises your risk because it leads to nutritional deficiencies.

Prevention Guidance

You can take steps to prevent some types of anemia. Here are key actions to take:

• Eat iron-rich foods. Good sources of iron include beans, dried fruits, eggs, lean red meat, salmon, iron-fortified breads and cereals, peas, tofu, and dark green leafy vegetables. Foods rich in vitamin C — such as oranges, strawberries, and tomatoes — help your body absorb iron.
• If you cannot prevent anemia through diet alone, ask your doctor whether any vitamin supplements are needed. It generally takes 3–6 months to replenish iron stores through supplements. If you are a strict vegetarian or vegan, talk to your doctor about how to get all the nutrients you need. Keep iron supplements out of reach of children. The high doses of iron in these supplements can quickly cause life-threatening poisoning if a child eats them.
• Avoid foods and drinks that block iron absorption. Black tea can reduce iron absorption.
• Take prenatal vitamins during pregnancy. Anemia in pregnancy is preventable and treatable. Your body makes more blood to support your baby’s growth during pregnancy, so you need more iron and other nutrients.
• Talk with your family. Some types of anemia can be inherited. Anemia caused by your genes cannot be prevented. If you have been diagnosed with an inherited type of anemia, suggest that family members visit their doctors for a checkup. If you plan to have children and have an inherited type of anemia, you can talk to a genetic counselor.
• Avoid substances that can trigger anemia. Certain toxins in the environment, such as pesticides or chemicals in the air, can cause some types of anemia. Other types of anemia can be triggered by certain foods or cold temperatures.

Diagnosis

Your doctor will use your medical history, a physical exam, and test results to diagnose anemia. Sometimes anemia is found during a test for another condition or when you try to donate blood.

During a physical exam, your doctor may:

• Check your tongue, nails, or the inner lining of your eyelids to see if they are pale
• Listen to your heart for a rapid or irregular heartbeat
• Feel your abdomen for an enlarged liver or spleen
• Check for signs of internal bleeding

Blood tests are the most common way to diagnose anemia. Because all women are at risk for anemia during pregnancy, doctors do blood tests to check for the condition at different stages of pregnancy.

The most important blood test is the complete blood count (CBC), which measures many parts of your blood. The CBC includes:

• Red blood cell count: A lower-than-normal count suggests anemia.
• Hemoglobin levels: Low hemoglobin points to anemia.
• Hematocrit. This measures how much space red blood cells take up in your blood.
• Mean corpuscular volume (MCV): This measures the average size of red blood cells, which gives clues about the type of anemia.

Other tests your doctor may order include:

• Bone marrow tests: These check whether your bone marrow is making normal amounts of blood cells.
• Colonoscopy: This procedure looks for bleeding or tumors in the colon.
• Endoscopy: This procedure looks for bleeding in the esophagus, stomach, and small intestine.
• Genetic tests: These look for changes in genes that control how your body makes red blood cells.
• Urine tests: These check kidney function and look for bleeding in the urinary tract.

Treatment and Management

Treatment for anemia depends on the type you have and how serious it is. People with mild anemia and no symptoms may not need treatment. People with severe anemia need treatment right away.

The main goals of treatment are to:

• Increase your red blood cell count or hemoglobin level
• Treat the underlying condition causing your anemia
• Prevent complications such as heart or nerve damage
• Relieve symptoms and improve your quality of life

Sometimes you can treat anemia simply with dietary changes and nutritional supplements to achieve appropriate iron, vitamin B12, and folate levels. Other times, more intensive treatment is needed.

Medicines

Medicines such as erythropoiesis stimulating agents (ESAs) help the bone marrow make more red blood cells. These are often used for people who also have kidney disease.

Medicines to suppress the immune system may be used when anemia is caused by an autoimmune disease. Autoimmune diseases occur when your immune system attacks your own cells, such as your blood cells or the bone marrow cells that make new blood cells.

Procedures

Medical procedures used to treat anemia include:

• Intravenous (IV) iron: This procedure delivers iron directly into a vein. It often takes only one or a few sessions to replenish iron.
• Blood transfusions: Transfusions quickly increase the amount of red blood cells and iron in the blood. They are used for serious anemia.
• Blood and bone marrow transplant: The transplant replaces damaged cells in the bone marrow with healthy cells. This is generally the best treatment option for people with severe aplastic anemia.
• Surgery or other medicines may be needed to stop internal bleeding.

Living With Anemia

To manage day-to-day fatigue and weakness, save your energy and ask for help with daily tasks. Balance periods of rest with periods of light activity like walking.

Be prepared for emergencies. Because of your blood condition, your needs may change. Keep the following on hand:

• Two weeks of prescription medicine
• Two weeks of food, water, and general medicines
• Your electronic medical records, insurance card, and emergency contact card

For children and teens with anemia, talk to them about how they can take an active role in their own care by learning about their condition and making decisions with their doctor. Older children and teens with severe anemia may have an increased risk of injury or infection, so talk with your doctor about ways to keep them as healthy as possible.

Healthy eating habits are essential for everyone with anemia. It is important to eat healthy to ensure your diet has iron-rich foods, as well as foods that contain vitamin B12.

If you have hemolytic anemia, reduce your chances of getting an infection by washing your hands often, avoiding people who have colds, and staying away from crowds.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find clinical trials on anemia.

Find Treatment

Your doctor may refer you to one or more specialists to help treat your anemia. These specialists may include:

• Hematologists: Doctors who specialize in blood disorders
• Gastroenterologists: Doctors who specialize in digestive system diseases
• Obstetrician/gynecologists: Doctors who specialize in women’s health and pregnancy
• Cardiologists: Doctors who specialize in heart and blood vessel diseases
• Neurologists: Doctors who specialize in nervous system disorders
• Registered dieticians: Accredited food and nutrition experts

Community Support

Managing anemia is easier with support. You do not have to go through it alone. Support groups and community organizations can provide empathy, acceptance, and wisdom.

For caregivers, two important tips are:

• Make sure you have support so you can better support your loved one.
• Ask for help before you feel overwhelmed. Look to others in your circle to pitch in so you can have time for self-care.

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.  

NIH supports research on the causes of blood disorders and ways to prevent and treat them. Common types of anemia are generally straightforward and easily treated, so NIH’s clinical research focuses on specific types, including sickle cell disease and thalassemia.

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.