What Is Anemia?

Anemia is defined as a low number of red blood cells. In a routine blood test, anemia is reported as a low hemoglobin or hematocrit. Hemoglobin is the main protein in your red blood cells. It carries oxygen, and delivers it throughout your body. If you have anemia, your hemoglobin level will be low too. If it is low enough, your tissues or organs may not get enough oxygen. Symptoms of anemia -- like fatigue or shortness of breath -- happen because your organs aren't getting what they need to work the way they should.

Anemia is the most common blood condition in the U.S. It affects almost 6% of the population. Women, young children, and people with long-term diseases are more likely to have anemia. Important things to remember are:

Certain forms of anemia are passed down through your genes, and infants may have it from birth.

Women are at risk of iron-deficiency anemia because of blood loss from their periods and higher blood supply demands during pregnancy.

Older adults have a greater risk of anemia because they are more likely to have kidney disease or other chronic medical conditions.

There are many types of anemia. All have different causes and treatments. Some forms -- like the mild anemia that happens during pregnancy -- aren’t a major concern. But some types of anemia maymay reflect a serious underlying medical condition