This case report describes a 54-year-old, asymptomatic man who presented with 
hyperkalemia on routine lab testing who was later found to have acute renal 
failure, unresponsive to fluid resuscitation, with minimal improvement after 
hemodialysis. After a comprehensive evaluation ruled out common causes of acute 
renal failure, the patient underwent testing with a bone survey, urine protein 
electrophoresis (UPEP), serum protein electrophoresis (SPEP), and 
immunoelectrophoresis for suspected plasma cell dyscrasia and received 
plasmapheresis for hyperviscosity syndrome and nephrotoxicity, which resulted in 
improved renal function. Lab results showed monoclonal gammopathy, elevated 
serum free light chains, and Bence Jones protein in the urine with a follow-up 
bone marrow biopsy indicating plasma cell dyscrasia. The patient received a 
diagnosis of multiple myeloma (MM) and was started on chemotherapy and 
immunosuppression. In patients presenting with acute renal failure with an 
evaluation ruling out prerenal and postrenal causes, multiple myeloma should be 
considered.