Abstract: FR-PO0477
Minimal Dipstick Proteinuria Masking Severe Light-Chain Multiple Myeloma-Associated Kidney Disease
Session Information
- AKI: Case Reports - TMA, Vasculitis, Immune-Mediated Injury, and Systemic Disease
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 102 AKI: Clinical, Outcomes, and Trials
Authors
- Capasso, Anthony, Westchester Medical Center Health Network, Valhalla, New York, United States
- Schwender, Eric, Westchester Medical Center Health Network, Valhalla, New York, United States
- Spira, Yaakov, Westchester Medical Center Health Network, Valhalla, New York, United States
Introduction
Multiple myeloma can cause acute kidney injury in several ways. One mechanism is by filtration of nephrotoxic light chains depositing in the tubules. Renal involvement portends a worse prognosis, and prompt treatment gives the best chance for recovery. A discrepancy between urine protein by dipstick and urine protein-to-creatinine ratio offers a diagnostic clue explained by filtration of Bence Jones proteins. We present a case in which recognition of this pattern allowed for prompt antineoplastic therapy and renal recovery.
Case Description
A 57-year-old woman with a history of well controlled type 2 diabetes mellitus was found to have a creatinine of 7.2 and a hemoglobin of 7.9 on outpatient labs during evaluation for cholestatic liver injury. Three months prior, the creatinine was 1.1 and hemoglobin 13. She felt well and review of systems was negative for fatigue, constipation, bone pain, or nausea. Urinalysis revealed only trace protein and blood, but no red blood cells on microscopy. Urine protein to creatinine ratio was 950 mg/g. Autoimmune serologies, complement, and infectious panels were unremarkable.
Free light chain assay demonstrated elevated kappa (1424 mg/L), lambda (68.7 mg/L), with a kappa/lambda ratio of 20.7. Serum protein electrophoresis did not reveal a monoclonal spike. Renal biopsy showed tubular basement membrane and glomerular capillary staining for kappa light chains only, consistent with light-chain deposition disease. Bone marrow biopsy revealed 40% kappa-restricted CD138-positive plasma cells, confirming multiple myeloma. The patient’s creatinine improved modestly with intravenous fluids but improved significantly following initiation of CyBorD (cyclophosphamide, bortezomib, dexamethasone) decreasing to 2.67 mg/dL by discharge.
Discussion
This case highlights light chain multiple myeloma as a cause of acute kidney injury, which can be missed if reliant solely on a negative serum M-spike. Bence Jones proteinuria should be considered when there is disparity between trace protein on dipstick and significant proteinuria on quantitative testing, as urinalysis detects albumin rather than filtered light chains. Early nephrology involvement, renal biopsy confirmation, and prompt hematologic therapy markedly improve renal recovery.