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Why might doctors examine bone marrow when diagnosing a blood disorder?

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blood disease Peripheral blood smear revealing histopathologic features indicative of a blast crisis in a case of chronic myelogenous leukemia (CML). Blast crisis occurs when one-fifth to one-third of the cells in the blood or bone marrow are immature blood cells, or blast cells. This phase of CML is characterized by fever, weakness, and an enlarged spleen.

Doctors examine bone marrow when diagnosing a blood disorder because it is the primary site of blood cell formation in adults, responsible for producing red blood cells, platelets, and the majority of white blood cells. Because the marrow contains stem cells that differentiate into these various blood components, examining it provides critical insights into the production and maturation stages of blood cells that cannot be fully determined through peripheral blood tests alone.123

A bone marrow aspiration—the direct removal of a small sample of marrow—is typically performed after initial blood studies indicate an abnormality. This examination is particularly valuable for diagnosing conditions such as leukemia, multiple myeloma, Gaucher disease, and unusual cases of anemia. Additionally, the procedure allows clinicians to assess iron stores and verify if malignant cells from other organs have metastasized to the bone marrow.13