What confirmatory test and finding are associated with multiple myeloma?

Multiple myeloma is a malignancy characterized by the proliferation of monoclonal plasma cells in the bone marrow, which can lead to various clinical manifestations including bone pain, anemia, increased susceptibility to infections, and renal impairment. The diagnosis of multiple myeloma is confirmed through specific laboratory and histological findings, one of the most definitive being a bone marrow biopsy.

A bone marrow biopsy showing greater than 10% monoclonal plasma cells is critical for establishing the diagnosis of multiple myeloma. In this condition, the presence of these abnormal plasma cells is a hallmark of the disease, as they produce excessive amounts of a single type of immunoglobulin, leading to various complications.

Other tests and imaging modalities, such as magnetic resonance imaging or ultrasound, may be used for evaluating associated conditions or complications, but they do not provide the definitive confirmation of multiple myeloma on their own. A serum creatinine level can indicate renal impairment, which is common in multiple myeloma, but it does not confirm the diagnosis. Therefore, the bone marrow biopsy with over 10% monoclonal plasma cells stands out as the key confirmatory test for diagnosing multiple myeloma.