What Is Red Bone Marrow?

Medically Reviewed by Kumar Shital, DO on September 15, 2023
Written by WebMD Editorial Contributor
4 min read

Bone marrow is a spongy tissue found inside some of your bones. Your body uses it to make white blood cells, red blood cells, and platelets.

Bone marrow is the soft tissue in your bones that makes and stores blood cells. There are two types of bone marrow. 

Red bone marrow. This type of bone marrow is found mostly in your flat bones, like your pelvis, scapula, skull, and sternum. Red bone marrow has stem cells that grow into red blood cells, white blood cells, and platelets. 

Yellow bone marrow. This type of bone marrow is found in your long bones and is usually surrounded by a layer of red bone marrow. It is mostly made of a high concentration of fat, which gives it a yellow color. 

Yellow bone marrow also stores stem cells. These stem cells become bone cells, cartilage, or fat. This fat gives your bones the nutrition they need to work properly.

Red bone marrow contains stem cells. Stem cells are not blood cells but cells that are used to create other cells. The stem cells in red bone marrow are called hematopoietic stem cells.‌

The stem cells in red bone marrow are used to make red blood cells, white blood cells, and platelets. This process of making new blood cells is called hematopoiesis. ‌

Red Blood Cells. Red blood cells contain hemoglobin, which gives blood its red color. The hemoglobin in red blood cells also binds to oxygen in the lungs.  

Red blood cells transport oxygen throughout the body, and the hemoglobin releases it into tissues. They also remove carbon dioxide from tissues and bring it back to the lungs.‌

White blood cells. These cells help fight infection by defending the body against viruses, bacteria, and other germs. Most of your white blood cells are outside of the blood in other tissues and organs in your body.

There are many types of white blood cells, and they fight infections in different ways. Some white blood cells make antibodies while others destroy invading cells. White blood cells include:

  • Lymphocytes: The three types of lymphocytes are T cells, B cells, and natural killer (NK) cells
  • Granulocytes: The three types of granulocytes are neutrophils, eosinophils, and basophils.
  • Monocytes: These white blood cells turn into macrophages, which eat foreign cells. 

Platelets. These cells make your blood clot and help stop bleeding. When you have an injury, platelets travel to the area and clump together to stop bleeding.

Bone marrow is very important for your health. Sometimes your bone marrow might be damaged or not work properly for different reasons. These can affect how you make blood cells. There are many different types of bone marrow disorders.

Cancer. Bone marrow problems can cause many different types of cancers.

Leukemia is a white blood cell cancer that can appear suddenly or grow slowly over time. It starts when one white blood cell that doesn’t work properly starts to replicate itself. This stops the body from being able to fight infections. 

As these nonfunctioning cells build up, they stop the production of normal white and red blood cells and platelets. There are many different types of leukemia.

Aplastic anemia. This rare condition is often caused by an injury to your bone marrow that causes a loss of stem cells. Without stem cells, your bone marrow can’t make blood cells. 

Aplastic anemia can also be caused by radiation, some chemicals, viruses, and certain medications and can also be inherited in rare cases. Sometimes it has an unknown cause.

Anemia. This condition is most often caused by low iron, low vitamin B12, or low folate. Your bone marrow needs these nutrients to be able to properly make red blood cells and hemoglobin. Without these nutrients, you might not have enough red blood cells.

Chronic infections, a lack of a kidney hormone called erythropoietin, toxins, drugs, or cancers can also cause anemia.

If you have anemia, you might have:

  • Tiredness
  • Weakness
  • Shortness of breath
  • Pale skin
  • Fainting

Plasma cell disorders. These are conditions where your body makes too many plasma cells. These cells are white blood cells that make antibodies to protect the body.

‌If these cells are abnormal and start to replicate out of control, they can cause damage to your organs and decrease your immunity. They can also cause a cancer called multiple myeloma. 

Myelodysplastic Syndromes. These diseases occur when your bone marrow makes too many malfunctioning blood cells. These cells are destroyed before they can make it into your blood. This leads to a lack of cells, which causes anemia, infections, bruising, and bleeding. ‌

Myeloproliferative neoplasms. These are conditions that happen when your bone marrow makes too much of one kind of blood cell. The other cells are crowded out, which causes shortages and problems in your body. 

Cancer treatment and other cancers. High amounts of radiation and chemotherapy can permanently damage or destroy stem cells. Some cancers can also spread to the bone marrow and cause problems with making blood cells.

Bone marrow disorders or other related problems might be treated with:

  • A bone marrow transplant
  • Blood transfusions
  • Iron, B12, or folate supplements, infusions, or needles
  • Chemotherapy
  • Immune system suppressing medications

Sometimes you might not have many symptoms of a bone marrow disorder. You may only become aware of a problem when you have an annual check-up and a complete blood count is done. It’s important to see your doctor regularly or when you don’t feel well to ensure that you stay healthy.