Bone marrow: What does it do in our bodies?

Our bones are not simply solid structures. Inside, there’s a liquid called bone marrow, which supports many life functions.

The bone marrow plays a vital role in helping the body maintain oxygen levels, fight infections and stop bleeding.

Bone marrow: the body’s blood cell factory

Bone marrow is a liquid, sponge-like material inside all bones. It plays a critical role in the production of blood cells and is found throughout the body, with larger amounts in bigger bones, such as the hip bone.

Bone marrow serves as the body’s “blood cell factory,” creating stem cells that develop into three types of blood cells.

• Red blood cells carry oxygen throughout the body.
• White blood cells help fight infection.
  • Neutrophils primarily fight bacteria.
  • Lymphocytes (including B and T cells) generally fight viruses. They also have a memory function that “learns” from vaccines and previously created antibodies.
  • Other white blood cells may address inflammation, allergies or parasites.
• Platelets help blood clot and prevent excessive bleeding.

By creating these cells, healthy marrow helps prevent severe anemia, supports immunity and reduces bleeding risk.

Bone marrow as we age

As we age, our bone marrow produces fewer cells. A rough estimate of the body’s percentage of cell-producing bone marrow is 100 minus a person’s age. For example, in someone who is 40 years old, we expect that about 60% of the bone marrow will be producing blood cells. This is sometimes referred to as “red” marrow.

The rest of the space inside the bone becomes filled in with fat cells. This is sometimes referred to as “yellow” marrow.

Bone marrow disorders

Bone marrow disorders can be due to cancerous or non-cancerous conditions.

Blood cancers are the most common bone marrow disorders diagnosed in adults. These include leukemias, lymphomas and other blood cancers. They often happen when blood cells fail to fully develop and don’t function normally.

Other bone marrow disorders include inherited bone marrow failure syndromes and acquired bone marrow failure syndromes. Inherited syndromes are associated with genetic mutations and are often diagnosed in childhood. Acquired syndromes may be linked to infection, medication, a weakened immune system or unknown causes.

Symptoms that can indicate a bone marrow disorder

• Frequent or lingering infections or viruses, including cold sores
• Fatigue, shortness of breath, dizziness or lightheadedness
• Easy or unexplained bruising
• Frequent nosebleeds or bleeding gums
• Tiny pinpoint spots on the skin

These symptoms may come on gradually and can be easy to overlook. Be sure to visit a doctor for any unexplained symptoms.

Diagnosing bone marrow disorders

Abnormal blood counts often provide the first clue to a bone marrow disorder.

A bone marrow biopsy is often needed to confirm the diagnosis. This generally involves taking a small portion of bone marrow from the hip bone so it can be analyzed.

In some cases, blood testing alone can identify certain mutations.

Treating bone marrow disorders

Treatment for a bone marrow disorder depends on the cause.

Some options include:

• Addressing infections
• Stopping a triggering medication
• Blood transfusions
• Immune-suppressing therapy
• Chemotherapy
• Immunotherapy or other targeted therapy
• A bone marrow or stem cell transplant

When a transplant may be needed for a bone marrow disorder

A transplant may be considered when there’s a non-reversible cause of bone marrow failure or to cure certain blood cancers.

Modern transplants are generally stem cell transplants and not actual bone marrow transplants.

This means the transplants use donor stem cells that have been medically encouraged to temporarily move from the bone marrow to the veins. The process allows the cells to be collected through a blood draw and prevents the need for harvesting marrow directly from a donor’s bone.

People with bone marrow disorders should discuss transplant options as early as possible after diagnosis. This allows the care team to start considering donor availability.

While a match, usually with a related donor, was once necessary, we’re now able to transplant with unrelated donors. The use of stem cell collection also allows us to transplant with older donors.

Preventing bone marrow disorders

Many bone marrow disorders cannot be fully prevented, however some risk factors include radiation, chemotherapy and use of certain medications.

To support normal blood-cell production, eat a balanced diet.

Deficiencies in nutrients such as iron, folate or B12 can sometimes mimic bone marrow problems. If you suspect a deficiency, talk to a primary care doctor before starting any supplements, because taking too much can lead to other problems.