A 55-year-old man is evaluated because his fatigue and exertional shortness of breath are worsening. He does not have any chronic medical conditions and does not take any medications. The physical examination reveals facial puffiness as well as bilateral lower extremity edema. A urine analysis reveals 3+ proteinuria. The image below depicts kidney biopsy findings with special staining under polarized light: Which of the following tests would be most helpful for establishing a specific diagnosis in this patient?

Question

A 55-year-old man is evaluated because his fatigue and exertional shortness of breath are worsening. He does not have any chronic medical conditions and does not take any medications. The physical examination reveals facial puffiness as well as bilateral lower extremity edema. A urine analysis reveals 3+ proteinuria. The image below depicts kidney biopsy findings with special staining under polarized light:  Which of the following tests would be most helpful for establishing a specific diagnosis in this patient?

Quizplus · Accepted Answer

Eductional Objective: Proteinuria and nephrotic syndrome are common symptoms of renal amyloidosis. A kidney biopsy reveals apple-green birefringence with Congo red staining under polarized light, confirming the diagnosis. The presence of a monoclonal protein in serum protein electrophoresis aids in the diagnosis of immunoglobulin light chain (AL) amyloidosis.

A 55-Year-Old Man Is Evaluated Because His Fatigue and Exertional