Multiple Myeloma with Renal Involvement Presenting with Atypical Clinical Findings

Multiple myeloma (MM) is a multisystem disorder where renal involvement worsens the prognosis significantly. Herein, we present two cases with an atypical clinical presentation. A 38-year-old female presented to our clinic with acute kidney injury (AKI) (urea: 47 mg/dl, creatinine: 3.0 mg/dl, calcium: 10.4 mg/dl, sedimentation: 49 mm/hour, proteinuria: 3.9 gr/day and urine sediment: 1-2 erythrocytes) after using gentamicin and nonsteroidal anti-inflammatory drugs (NSAIDs) for 6 weeks because of cystitis. Co-existence of cast nephropathy and IgA nephropathy was detected with renal biopsy while kappa light chain myeloma was detected with bone marrow biopsy. The second case was a 71-year-old male with normal preoperative creatinine levels while AKI developed following NSAID use after right lobectomy for non-small cell lung cancer (urea: 210 mg/dl, creatinine: 9.7 mg/dl, potassium: 6.1 mmol/L, calcium: 9.1 mg/dl, sedimentation: 63 mm/hour and proteinuria: 6 gr/day). The patient’s renal biopsy revealed cast nephropathy accompanied by nephrosclerosis. Lambda light chain myeloma was diagnosed with bone marrow biopsy. MM should be kept in mind in patients who develop AKI after use of nephrotoxic drugs without additional risk factors for the development of AKI and in patients in a higher risk age group for MM.