A 75-year-old man comes to the physician because of fatigue and low back pain. He takes ibuprofen as needed for lower back pain. He has no prior medical history and takes no medications. Physical examination shows tenderness to palpation over the lumbar spine. There is pedal edema. Radiographs reveal lytic bone lesions. Laboratory results are as follows:
Urine dipstick is negative for protein, but quantitative measurement reveals elevated 24-hour urinary protein excretion. Urine electrophoresis is most likely to detect which of the following?

Question

A 75-year-old man comes to the physician because of fatigue and low back pain. He takes ibuprofen as needed for lower back pain. He has no prior medical history and takes no medications.  Physical examination shows tenderness to palpation over the lumbar spine. There is pedal edema. Radiographs reveal lytic bone lesions.  Laboratory results are as follows: 
  Urine dipstick is negative for protein, but quantitative measurement reveals elevated 24-hour urinary protein excretion.  Urine electrophoresis is most likely to detect which of the following?

Quizplus · Accepted Answer

Eductional Objective: Multiple myeloma should be suspected in elderly patients who have any combination of osteolytic lesions, hypercalcemia, anemia, or acute kidney injury.  Renal disease is most commonly caused by light chain cast nephropathy, in which free light chains form obstructive casts in the renal tubules.  Monoclonal paraproteins are not detected by urine dipstick (which detects only albumin), but both spot and 24-hour protein concentrations will be elevated.

A 75-Year-Old Man Comes to the Physician Because of Fatigue