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myeloma cast nephropathy; light chain cast nephropathy
Etiology:
- always associated with multiple myeloma.
Epidemiology:
- 20% of patients with multiple myeloma
Pathology:
- Ig light chains in urine
- renal tubular injury
- obstructive uropathy of tubular origin
- filtered light chains endocytosed by proximal tubule cells are nephrotoxic, resulting in proximal tubular dysfunction
- always associated with multiple myeloma
Clinical manifestations:
- acute or slowly progressive kidney injury
Laboratory:
- 24 hour urine protein
- high levels of Ig light chains in urine
- albumin in urine may be normal
- nephrotic level proteinuria, but not nephrotic syndrome (no edeme
- urine dipstick detects albumin, not Ig light chains
- serum protein electrophoresis
- high serum free light chains
- urine protein electrophoresis
- immunofixation electrophoresis
- hypercalcemia
- anemia
Radiology:
- lytic bone lesions may be noted
Differential diagnosis:
- AA amyloidodsis
- frequently present with the nephrotic syndrome
- history of an inflammatory disease, edema, hypoalbuminemia
- monoclonal gammopathy of renal significance
- no hypercalcemia, anemia, or lytic bone lesions
- fibrillary glomerulopathy
- hematuria, hypertension
Management:
- treatment of multiple myeloma
- reduce free Ig light chains with chemtherapy
- avoid bisphosphonates
- pamidronate may induce acute renal failure & nephrotic syndrome
- zoledronate may induce acute tubular necrosis
- contraindicated if GFR > 30 mL/min
- avoid NSAIDs, especially in patients with volume depletion
General
multiple myeloma; plasmacytoma/plasma cell myeloma
nephropathy
References
- Medical Knowledge Self Assessment Program (MKSAP) 15, 16, 18, 19.
American College of Physicians, Philadelphia 2009, 2012, 2018, 2021.
- Medical Knowledge Self Assessment Program (MKSAP) 20
American College of Physicians, Philadelphia 2025
- Mene P, Stoppacciaro A, Lai S, et al.
Light chain cast nephropathy in multiple myeloma: prevalence, impact and
management challenges.
Int J Nephrol Renovasc Dis. 2022;15:173-183.
PMID: 35592304