What are the CRAB features of multiple myeloma?

• A. Hypercalcemia, Renal failure, Anemia, Bone lesions (lytic); monoclonal protein (M-protein) in serum/urine
• B. Hyperkalemia, Hypertension, Hypophosphatemia, Osteoporosis
• C. Hyperglycemia, Polycythemia, Liver failure, Retinopathy
• D. Hypocalcemia, Acute kidney injury, Leukopenia, Osteoporosis

Answer: (A)

CRAB features are the end-organ damages that multiple myeloma typically causes: hypercalcemia from bone resorption, renal failure from light-chain–related nephropathy and calcium elevation, anemia from marrow replacement, and bone lesions due to osteolytic activity. These problems reflect how the malignant plasma cells disrupt bone and kidney function and crowd out normal blood cell production. In addition, the presence of a monoclonal protein (M-protein) in serum or urine is a hallmark finding in myeloma and helps confirm the diagnosis, often detected by electrophoresis tests. So the best answer captures both the CRAB end-organ consequences and the monoclonal protein feature that accompanies the disease. Other options mix conditions that aren’t characteristic CRAB manifestations of multiple myeloma.