In multiple myeloma, what does "CRAB" stand for?

In the context of multiple myeloma, the acronym "CRAB" is used to summarize the four most common clinical features associated with the disease: HyperCalcemia, Renal failure, Anemia, and Bone lesions. Each element of this acronym helps in identifying the complications that may arise due to the underlying pathophysiology of multiple myeloma.

Hypercalcemia occurs as a result of increased osteoclastic activity prompted by malignant plasma cells, which release osteoclast-activating factors. This can lead to symptoms such as confusion, thirst, and constipation. Renal failure is frequently observed in patients due to the deposition of light chains (from monoclonal immunoglobulins) in the renal tubules, which can lead to acute kidney injury. Anemia is common in multiple myeloma due to the disruption of normal hematopoiesis and the replacement of bone marrow by neoplastic plasma cells. Finally, bone lesions can result from the increased breakdown of bone tissue, leading to osteolytic lesions that may manifest as pain or fractures.

These features, represented by the "CRAB" mnemonic, are critical for both diagnosing multiple myeloma and monitoring its complications, making this answer the most accurate in describing the hallmark signs