Lytic bone lesions, hypercalcemia, anemia, and rouleaux = MM

• Multiple myeloma = Bone pain (often in the back) + Lytic bone changes on imaging + Anemia (due to plasma cells crowding out other hematopoeitic cells in bone marrow) + Elevated calcium concentration (due to lytic bone lesions) + Rouleaux formation on peripheral smear (due to sticky immunoglobulin proteins causing RBCs to stack up)
• Key idea: If you see a patient with signs of kidney disease (elevated creatinine/BUN) and hypercalcemia, you should have a high index of suspicion for multiple myeloma because most other forms of kidney disease lead to hypocalcemia (due to binding of phosphate to calcium and reduced vitamin D activation)