Bone Marrow Disorders

What bone marrow does

Bone marrow is the spongy tissue inside large bones such as the hips, spine and breastbone. It contains stem cells that produce every day billions of:

• red blood cells, which carry oxygen
• white blood cells, which fight infection
• platelets, which help blood clot

Disorders arise when the stem cells are damaged, when they acquire genetic changes that make them grow abnormally, or when the marrow is crowded out by other cells.

Main types of bone marrow disorders

Symptoms

Symptoms reflect which cells are affected:

• Low red cells (anemia): tiredness, weakness, pale skin, breathlessness, dizziness, a fast heartbeat
• Low white cells (neutropenia): frequent, unusual or severe infections, mouth ulcers, fever
• Low platelets (thrombocytopenia): easy bruising, nosebleeds, bleeding gums, heavy periods, tiny red spots on the skin
• Too many cells: headaches, itching after bathing, red skin, blood clots (polycythemia vera); enlarged spleen causing fullness under the left ribs (myelofibrosis)
• Cancer-related: fevers, night sweats, weight loss, bone pain

Some disorders, such as early MDS or chronic leukemias, cause no symptoms and are found on routine blood tests.

Causes and risk factors

• Age: most marrow cancers and MDS are more common after 60
• Previous chemotherapy or radiation therapy
• Chemical exposures: benzene and some pesticides
• Autoimmune attack on stem cells, the usual cause of aplastic anemia
• Medicines and infections: some drugs, hepatitis viruses, Epstein-Barr virus, parvovirus B19
• Inherited conditions
• Smoking, which increases risk of some leukemias and MDS

Nutritional deficiencies (B12, folate, copper) and heavy alcohol use can also suppress the marrow and mimic marrow disease.

Diagnosis

1. Complete blood count (CBC) with differential, showing levels of each cell type.
2. Blood smear: examining cells under a microscope for abnormal shapes or immature cells.
3. Other blood tests: B12, folate, iron, kidney and liver function, reticulocyte count, protein electrophoresis for myeloma.
4. Bone marrow aspiration and biopsy: a needle takes a sample of liquid marrow and a small core of bone from the back of the hip bone under local anesthetic. It takes about 15 to 30 minutes and causes a deep ache for a day or two.
5. Genetic and molecular tests on the marrow, which classify the disease and guide treatment.
6. Imaging to check the spleen, lymph nodes and bones.

Treatment

Treatment depends on the specific disorder, its severity and the person's age and health.

• Watchful waiting for slow, early disorders such as MGUS, low-risk MDS or some chronic leukemias
• Transfusions of red cells or platelets to manage symptoms
• Growth factors that stimulate red or white cell production
• Immunosuppressive therapy for aplastic anemia
• Targeted therapies: such as tyrosine kinase inhibitors for chronic myeloid leukemia or JAK inhibitors for myelofibrosis
• Chemotherapy and hypomethylating agents for leukemia and higher-risk MDS
• Venesection (removing blood) and low-dose aspirin for polycythemia vera, as advised by a specialist
• Allogeneic stem cell transplant: replaces the diseased marrow with donor stem cells. It is the only potential cure for many marrow disorders but carries significant risks

Infection prevention is important when white cells are low: hand hygiene, food safety, vaccines as advised, and urgent treatment for any fever.

Outlook

Outlook varies enormously. MGUS and many chronic myeloproliferative neoplasms are compatible with a normal or near-normal life span with monitoring. Aplastic anemia often responds well to immunosuppression or transplant, especially in younger people. Acute leukemias and high-risk MDS are serious, but treatments have improved substantially, and many people achieve remission.

Frequently asked questions

What are the symptoms of a bone marrow disorder?

Common symptoms are tiredness, pale skin and breathlessness from anemia, frequent infections from low white cells, and easy bruising or bleeding from low platelets. Some disorders cause fevers, night sweats, weight loss or bone pain. Many are found on routine blood tests.

Is bone marrow disease cancer?

Some are and some are not. Leukemias, multiple myeloma, MDS and myeloproliferative neoplasms are blood cancers or cancer-like conditions. Aplastic anemia and marrow suppression from nutritional deficiencies or medicines are not cancers.

How is a bone marrow disorder diagnosed?

It starts with a complete blood count and blood smear. If those are abnormal, a bone marrow aspirate and biopsy, taken from the hip bone under local anesthetic, usually confirms the diagnosis, with genetic tests to classify the disease.

Can bone marrow disorders be cured?

Some can. Aplastic anemia and some leukemias can be cured with treatment or stem cell transplant. Others, such as myeloma and many myeloproliferative neoplasms, are usually controlled long-term rather than cured.