Abstract: PUB191
Lambda Light-Chain Deposition Disease Unmasked by Disproportionate AKI in a Patient with Diabetic Nephropathy
Session Information
Category: Onconephrology
- 1600 Onconephrology
Authors
- Ali, Ali, HCA Houston Healthcare Clear Lake, Webster, Texas, United States
- Ibrahim, Nawras, HCA Houston Healthcare Clear Lake, Webster, Texas, United States
- Ghosoun, Nour, HCA Houston Healthcare Clear Lake, Webster, Texas, United States
- Achkar, Katafan, HCA Houston Healthcare Clear Lake, Webster, Texas, United States
Introduction
MIDD is a rare cause of AKI that may be masked by coexisting glomerulopathies. Lambda-restricted LCDD accounts for only 10–20% of cases. We present a case where AKI disproportionate to known diabetic nephropathy revealed lambda LCDD from underlying multiple myeloma.
Case Description
A 68-year-old man with type 2 diabetes (A1c 5.7) presented with anasarca, AKI (Cr 2.8→3.3, GFR 23), sub-nephrotic proteinuria (UPCR 2.39), refractory hyperkalemia (5.8→7.5) requiring hemodialysis, low C4 with normal C3, and normocytic anemia (Hb 6.4). Cryoglobulin, ANA, ANCA, and hepatitis panel were negative. With other etiologies excluded, the isolated low C4 suggested a paraprotein-mediated process. SPEP showed M-spike 0.6; immunofixation confirmed IgG lambda monoclonal protein. Free lambda was 23,000 mg/L. Bone marrow showed 80% lambda-restricted plasma cells. Kidney biopsy showed lambda-restricted MIDD with linear immunofluorescence along tubular and glomerular basement membranes, superimposed on diabetic nodular glomerulosclerosis with 30% fibrosis. EM confirmed non-organized deposits without fibrils, excluding amyloidosis.
Discussion
AKI disproportionate to known diabetic nephropathy should prompt paraprotein screening, particularly with unexplained low C4 and anemia. LCDD and diabetic nephropathy can coexist — NDRD is found in up to 59% of biopsied diabetic patients — and attributing injury to diabetes alone risks missing a treatable plasma cell disorder.