A 74-year-old man presents with fatigue, shortness of breath on exertion, and back and rib pain, which is made worse with movement. Investigations reveal he is anemic, calcium, urea, and creatinine are elevated. X-rays reveal multiple lytic lesions in the long bones and ribs, and protein electrophoresis is positive for an immunoglobulin G (IgG) paraprotein. Which of the following is the most likely mechanism for the renal injury?
High-Yield Explanation
In multiple myeloma, tubular damage by light chains is almost always present. The injury is a direct toxic effect of the light chains or indirectly from the inflammatory response. Infiltration by plasma cells and glomerular injury is rare. Hypercalcemia may produce transient or irreversible renal damage as do amyloid and myeloma cell infiltrates.