What Are the Different Types of Anemia?

There are many types of anemia. Although all anemia types are characterized by low levels of red blood cells or red blood cells that don’t work as they should, there can be significant differences in the causes, severity, and treatment between each type.

Anemia is typically diagnosed with blood tests that look at the number, shape, and health of your red blood cells. If the condition is diagnosed as anemia, treatment will depend on the type of anemia you have.

Anemia is typically divided into three main types, each of which can have different causes:

• Microcytic: With microcytic anemia, red blood cells don’t have enough hemoglobin. As a result, the red blood cells are smaller than normal.
• Normocytic: In normocytic anemia, there aren’t enough red cells to meet your body’s needs. Normocytic anemia tends to accompany certain chronic diseases.
• Macrocytic: Macrocytic anemia happens when bone marrow makes red blood cells that are larger than normal.

Let’s take a closer look at these three types of anemia in more detail.

In microcytic anemia, red blood cells are smaller than they should be. This happens because your red blood cells don’t have enough hemoglobin — a protein in red blood cells that helps carry oxygen through your bloodstream and throughout your body.

The types of conditions that can cause microcytic anemia include:

• Iron-deficiency anemia: Iron-deficiency anemia is the most common cause of microcytic anemia, and it happens when your body doesn’t have sufficient iron to make hemoglobin. Without enough hemoglobin, your red blood cells have a harder time delivering oxygen throughout your body. As a result, you may feel tired and out of breath. Common causes of iron-deficiency anemia include:
  • blood loss due to internal bleeding, heavy menstrual periods, or surgery
  • not enough iron in your diet
  • difficulty absorbing iron
  • pregnancy
  • childbirth
• Sideroblastic anemia: In sideroblastic anemia, your bone marrow is unable to make enough healthy red blood cells. Depending on the cause, sideroblastic anemia can be microcytic (red blood cells are too small) or macrocytic (red blood cells are too large). You can be born with this condition, or it may develop due to certain medications or exposure to some types of toxins and chemicals.
• Thalassemia: Thalassemia is a blood disorder that’s caused by inherited genes. If you have thalassemia, your body makes an abnormal form of hemoglobin. There are different types of thalassemia, and each type can affect your red blood cells in a different way.
• Lead toxicity: High levels of lead exposure may also cause a disruption to how your body produces hemoglobin and red blood cells.

The treatment of microcytic anemia depends on the underlying cause. For instance:

• For iron-deficiency anemia, treatment may include iron supplements, increased dietary intake of iron-rich foods, or vitamin C supplements (which may help with iron absorption).
• For less severe sideroblastic anemia, treatment may include vitamin B6 (pyridoxine) therapy.
• For more severe sideroblastic anemia or severe thalassemia, a bone marrow transplant or blood transfusions may be necessary.

With normocytic anemias red blood cells are all the same size, but there aren’t sufficient levels of circulating red blood cells to meet your body’s needs.

Normocytic anemia is most often caused by an underlying chronic illness. Less frequently, you may be born with it, or it can be a side effect of a medication.

The most common conditions that can affect red blood cell production and lead to normocytic anemia include:

• Anemia of chronic disease (ACD): Diseases that cause inflammation are the underlying cause of ACD. Inflammation can reduce the production of red blood cells or cause weaker red blood cells to be produced that die more quickly. Many types of chronic diseases that cause inflammation can lead to ACD, including:
  • autoimmune conditions such as lupus or rheumatoid arthritis
  • infections such as tuberculosis or transmissions of HIV
  • inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease
  • cancer
• Blood loss: Losing too much blood because of an injury, heavy periods, surgery, or bleeding in the gastrointestinal tract can all lead to normocytic anemia.
• Hemolytic anemia: Hemolytic anemia causes red blood cells to break down and die too rapidly. Sometimes the condition is mild and doesn’t need treatment. Often this type of anemia can be successfully treated once the cause is determined. There are multiple causes of hemolytic anemia, including:
  • inherited conditions such as sickle cell anemia, thalassemia, or glucose-6-phosphate dehydrogenase (G6PD) deficiency
  • infections
  • medication side effects
• Aplastic anemia: Aplastic anemia occurs when the stem cells in the bone marrow aren’t able to make enough red blood cells. This anemia is often a result of the body’s immune system attacking bone marrow stem cells, and it can also occur after:
  • a severe viral infection
  • treatment with radiation
  • exposure to toxic chemicals
• Bone marrow infiltrative disorders: Red blood cells live for about 120 days. Once red blood cells die off, they’re replaced by new red blood cells in the bone marrow. Some types of diseases can affect the bone marrow and make it harder for red blood cells to be produced. This includes conditions such as:
  • myelofibrosis (a type of bone marrow cancer)
  • leukemia (cancer of the blood cells)
  • cancer metastases (cancer that starts somewhere else in the body and spreads to the bones)

The treatment of normocytic anemia depends on the underlying cause.

With macrocytic anemia, the bone marrow makes red blood cells that are larger in size than normal red blood cells. This type of anemia can develop if your body lacks certain types of nutrients that it needs.

There are two kinds of macrocytic anemia: megaloblastic anemia and nonmegaloblastic anemia.

Megaloblastic anemia

Megaloblastic anemia happens when you don’t get enough vitamin B12 or folate. If your body doesn’t have enough of these nutrients, your bone marrow will have a hard time making healthy red blood cells.

Treatment of megaloblastic anemia may include taking vitamin B12 and folate supplements and increasing your dietary intake of these vitamins.

Some people have an autoimmune condition called “pernicious anemia” that prevents their bodies from absorbing vitamin B12. If left untreated, pernicious anemia can cause irreversible damage to the nervous and digestive systems.

Treatment of pernicious anemia usually involves vitamin B12 injections that are given daily or weekly until B12 levels are within a healthy range.

Nonmegaloblastic anemia

With nonmegaloblastic anemia, certain medical conditions may affect how easily your body is able to absorb the nutrients needed for healthy red blood cell production. The most common conditions that can cause nonmegaloblastic anemia include:

• hypothyroidism, also known as an underactive thyroid
• alcohol use disorder
• liver disease
• hereditary spherocytosis, a condition that causes your red blood cells to be shaped like spheres instead of flattened discs
• myelodysplastic syndromes, a group of conditions that affects your body’s ability to make healthy blood cells

If nonmegaloblastic anemia is caused by an underlying chronic condition, treatment will focus on the underlying disease that’s causing the anemia.

Some types of anemia, such as those that are inherited, can’t be prevented. However, you can take steps to help reduce the risk of some other types of anemias, including:

• eating a healthy diet containing iron-rich foods such as shellfish, poultry, and beef
• eating vegetables to help your body absorb iron
• getting enough folate and B12 in your diet or taking supplements
• talking with a doctor about hormonal therapy if you have heavy menstrual bleeding

Anemia is a health condition that occurs when you don’t have enough red blood cells, and it causes symptoms such as lightheadedness, fatigue, weakness, and shortness of breath.

There are different types of anemia. They share similar symptoms but have different causes as well as different treatments and severity levels. Some anemias, such as megaloblastic anemia, can be treated with dietary changes. Other anemias, such as sickle cell anemia, are chronic and inherited.

You can’t prevent inherited types of anemia, but you can take steps to help your body get the nutrients it needs to prevent anemias caused by a lack of iron, B12, or folate.