Multiple myeloma frequently impacts the kidneys, with up to half of patients presenting with reduced kidney function at diagnosis.1-4 The most common cause of kidney damage is light chain cast nephropathy,5,6 and Bence Jones proteinuria is present in 64%-96% of cases at diagnosis.7-9 Nephrologists must be keenly aware of multiple myeloma as a potential diagnosis in cases of undifferentiated kidney dysfunction. Because of this, some employ a commonly taught “clinical pearl” assessing for discrepancy between the urinary protein-creatinine ratio (UPCR) and urinary albumin-creatinine ratio (UACR) as a surrogate screen for multiple myeloma.