A 55-year-old man presents with bone pain, progressive renal insufficiency, and fatigue. Laboratory investigations reveal normocytic anemia, hypercal…

The diagnosis of symptomatic multiple myeloma requires clonal bone marrow plasma cells >= 10% (or biopsy-proven plasmacytoma) plus evidence of at least one myeloma-defining event (CRAB criteria: Calcium elevation, Renal insufficiency, Anemia, Bone lesions). However, smoldering multiple myeloma can also be diagnosed with >= 10% plasma cells if CRAB features are absent. Importantly, biomarkers of malignancy (like bone marrow plasma cells >= 60%, involved/uninvolved free light chain ratio >= 100, or >1 focal MRI lesion) can also define active myeloma even in the absence of traditional CRAB features. However, in this patient, the hypercalcemia, renal failure, and anemia are already clinical CRAB features. Option B highlights that the renal failure and hypercalcemia directly fulfill the CRAB criteria, establishing active multiple myeloma.