American Board of Internal Medicine (ABIM) Certification Practice Exam

When is therapy required for multiple myeloma?

1. When plasma cells represent more than 20% of marrow

2. When plasma cells represent more than 10% of the total marrow cellularity

3. When the serum calcium is elevated

4. When patient experiences bone pain

The correct answer is: When plasma cells represent more than 10% of the total marrow cellularity

Therapy is indicated for multiple myeloma when plasma cells make up more than 10% of the total marrow cellularity, which reflects the presence of a significant clonal expansion of plasma cells. This threshold is recognized in clinical guidelines as it reflects a higher burden of disease, often associated with clinical symptoms or complications. In multiple myeloma, the presence of over 10% plasma cells in the bone marrow is generally used as one of the diagnostic criteria indicating that the disease is active and warrants treatment. The initiation of therapy at this stage helps manage the disease actively and mitigate potential complications associated with more advanced stages of the disease. While elevated serum calcium and bone pain are important clinical considerations in the management of multiple myeloma, they are not the primary criteria for starting treatment. These findings typically indicate complications arising from the disease rather than being sole determinants for initiating therapy. Identifying the percentage of plasma cells in the marrow provides a more direct assessment of the myeloma's progression and activity, which is essential for guiding therapeutic intervention.