What is anemia?

Anemia is a condition in which the blood has too little hemoglobin, the protein inside red blood cells that carries oxygen throughout the body. Anemia can happen when there are fewer red blood cells than normal or when each red blood cell contains less hemoglobin than it should.

Because oxygen is essential for producing energy, people with anemia may feel tired, weak, dizzy, or short of breath. Some people may also notice pale skin, headaches, or a fast heartbeat.

What do red blood cells and hemoglobin do?

Red blood cells are made in the bone marrow and circulate in the bloodstream for about 120 days. Their main job is to transport oxygen from the lungs to the rest of the body. Hemoglobin binds oxygen in the lungs and releases it to tissues and organs that need it to function correctly.

When red blood cells are too few, damaged, or low in hemoglobin, the body receives less oxygen, leading to anemia symptoms.

What causes anemia?

Anemia can develop for many reasons, and in some people, more than one cause may be present at the same time. Doctors often group the causes of anemia based on what happens to red blood cells.

Problems with red blood cell production

Anemia can occur if the bone marrow does not make enough red blood cells. This may happen due to chronic illness, kidney disease, bone marrow disorders, nutritional deficiencies, or certain medications.

Problems with red blood cell maturation

In some conditions, red blood cells are produced but do not mature normally. These cells may be larger or smaller than normal or may not function properly. Vitamin deficiencies, such as low vitamin B12 or folate, are common causes.

Increased loss or destruction of red blood cells

Red blood cells may be removed from the bloodstream faster than normal. This can happen with bleeding, inherited red blood cell disorders, immune-related conditions, or mechanical damage to red blood cells. When red blood cells are destroyed early, the condition is called hemolytic anemia.

Common types of anemia

Iron deficiency anemia

Iron deficiency anemia occurs when the body does not have enough iron to make hemoglobin. It is the most common type of anemia and may be caused by blood loss, low dietary iron, or problems absorbing iron from food.

Anemia of chronic disease

This type of anemia is seen in people with long-term illnesses such as infections, autoimmune diseases, cancer, or chronic kidney disease. In these conditions, the body has difficulty using stored iron and producing red blood cells.

Megaloblastic anemia

Megaloblastic anemia occurs when red blood cells cannot mature properly, most often due to low levels of vitamin B12 or folate. The red blood cells become abnormally large and less effective at carrying oxygen.

Hemolytic anemia

Hemolytic anemia happens when red blood cells are destroyed faster than they can be replaced. Inherited conditions, autoimmune diseases, infections, medications, or mechanical damage to red blood cells may cause this.

How is anemia diagnosed?

Anemia is usually diagnosed with a blood test called a complete blood count (CBC). This test measures hemoglobin levels, red blood cell count, and red blood cell size and shape. Additional blood tests may be ordered to identify the underlying cause, such as iron studies, vitamin levels, or tests for hemolysis.

Why is identifying the cause of anemia important?

Anemia is a sign of an underlying problem, not a disease by itself. Identifying the cause helps guide appropriate treatment. Some types of anemia improve with supplements, while others require treatment of an underlying medical condition or more specialized care.

Questions to ask your doctor

• What type of anemia do I have?

• What is causing my anemia?

• Do I need additional blood tests or other investigations?

• Will I need iron, vitamins, or other treatments?

• How will my anemia be monitored over time?