Also known as Iron-poor blood, Low blood, Tired blood
Anemia is a condition in which your blood has a lower-than-normal amount of 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. If you have anemia, your body does not get enough oxygen-rich blood. This can cause you to feel tired or weak. You may also have shortness of breath, dizziness, headaches, or an irregular heartbeat.

There are many types and causes of anemia. Mild anemia is a common and treatable condition that can occur in anyone. Some people are at a higher risk for anemia, including women during their menstrual periods and pregnancy and people who donate blood frequently, do not get enough iron or certain vitamins, or take certain medicines or treatments, such as chemotherapy for cancer.

Anemia may also be a sign of a more serious condition. It may result from chronic bleeding in the stomach. Chronic inflammation from an infection, kidney disease, cancer, or autoimmune diseases can also cause the body to make fewer red blood cells.

Your doctor will consider your medical history and physical exam and test results when diagnosing and treating anemia. He or she will use a simple blood test to confirm that you have low amounts of red blood cells or hemoglobin. For some types of mild to moderate anemia, your doctor may recommend over-the-counter or prescription iron supplements, certain vitamins, intravenous iron therapy, or medicines that make your body produce more red blood cells. To prevent anemia in the future, your doctor may also suggest healthy eating changes. If you have severe anemia, your doctor may recommend red blood cell transfusions.

Visit Anemia for more information about this topic.

Participate in NHLBI Clinical Trials

We lead or sponsor many studies on anemia. See if you or someone you know is eligible to participate in our clinical trials.

Do you have a critically ill child in the ICU?

The study will compare the use of fresh red blood cells and the standard blood bank cells, which are typically older, for blood transfusions in critically ill children in the intensive care unit (ICU). To participate, your child must be between 3 days and 16 years of age and require a blood transfusion in the ICU. The study is taking place at multiple locations across the United States, Canada, and Europe.

Were you or your child diagnosed with Diamond-Blackfan anemia?

The registry is collecting information from people with Diamond-Blackfan anemia to improve understanding of the condition. To participate, you or your child must be diagnosed with Diamond-Blackfan anemia. You will complete a questionnaire, provide access to your medical and laboratory records, and answer questions with study staff over the telephone. This study is taking place in Long Island, New York.
View more information about Diamond-Blackfan Anemia Registry (DBAR).

Did you have a heart attack and want to help determine the best strategy for blood transfusion?

The study is comparing two strategies for blood transfusions in patients who have had a heart attack and have anemia. This will help doctors decide whether to give a blood transfusion right away for heart attack patients who are anemic or wait and see whether their condition improves. To participate, you must be an adult hospitalized for a heart attack and have anemia. The study is taking place in New Brunswick, New Jersey.

Did you recently give birth to a very low birth-weight infant?

The study is investigating how anemia and red blood cell transfusions affect oxygen levels in the digestive tract of very low birth-weight infants. To participate, your newborn must have had a very low birth-weight and be within seven days of birth. The study is taking place in Atlanta, Georgia.

Do you want to take part in blood research?

The study aims to screen patients at the National Institutes of Health Clinical Center who have a blood disorder such as anemia and who may be eligible to participate in studies in the Hematology Branch. It will also determine whether it is safe for you to participate in those studies. To be screened, you or your child must be at least 2 years old and seen at the Clinical Center in Bethesda, Maryland.
View more information about Screening for Hematology Branch Protocols.
More Information
Image of the cover of the January edition of the Transfusion journal
Credit: Transfusion journal
Research Feature
Every two seconds someone in the United States needs blood. Five million people receive a blood transfusion every year in the U.S. In a country where blood is perennially in short supply, it is the most common medical procedure of all. Yet giving to a blood bank is not always a slam dunk—some people get turned away because of strict rules meant for...