From the Guidelines
Myeloma kidney is a severe complication of multiple myeloma, characterized by kidney damage caused by abnormal light chain proteins, and its management should prioritize prompt treatment with bortezomib and dexamethasone-based regimens to improve renal function and overall survival, as evidenced by recent studies 1.
Definition and Pathophysiology
Myeloma kidney, also known as light chain cast nephropathy, occurs when abnormal light chain proteins produced by cancerous plasma cells in multiple myeloma patients damage the kidneys. These light chains can directly injure kidney tubules, form casts that block urine flow, or trigger inflammation, leading to acute kidney injury (AKI) or chronic kidney disease (CKD) 1.
Clinical Presentation and Diagnosis
Patients with myeloma kidney typically experience symptoms such as decreased urine output, swelling in the legs, fatigue, and high blood pressure. The incidence of AKI at diagnosis is 16-31% when measured by serum creatinine concentration, and 16-22% when defined by estimated glomerular filtration rate (eGFR) 1. Diagnosis is based on laboratory tests, including serum creatinine, eGFR, and urine protein electrophoresis to detect light chains.
Treatment and Management
Treatment should focus on addressing the underlying multiple myeloma with chemotherapy regimens such as bortezomib and dexamethasone-based regimens, as recommended by the European Myeloma Network 1. Supportive measures include:
- Maintaining good hydration (2-3 liters of fluid daily)
- Avoiding nephrotoxic medications like NSAIDs
- Using plasmapheresis to remove excess light chains from the blood, although its role is still unclear and being assessed in clinical trials 1 Early diagnosis and prompt treatment are crucial, as kidney function can sometimes be restored if the myeloma is controlled quickly, and recovery of kidney function reverses the negative impact on overall survival 1.
Prognosis and Outcomes
Renal impairment imposes the greatest impact on overall survival (OS) in multiple myeloma patients, even after adjusting for other cofactors and comorbidities 1. However, with prompt treatment and recovery of kidney function, patients can experience improved outcomes and reduced mortality risk 1.
From the Research
Definition of Myeloma Kidney
- Myeloma kidney, also known as cast nephropathy, is a condition where the kidneys are damaged due to the excessive production of light chains by myeloma cells 2.
- This damage leads to the formation of casts in the renal tubules, resulting in renal impairment 3, 4.
Causes of Myeloma Kidney
- The primary cause of myeloma kidney is the precipitation of monoclonal free light chains with uromodulin in renal tubules, leading to cast nephropathy 3.
- Other precipitating factors, such as dehydration, nephrotoxic treatments, and hypercalcemia, can also contribute to the development of myeloma kidney 3, 4.
Clinical Presentation and Diagnosis
- Myeloma kidney can present with acute kidney injury, characterized by a rapid decline in renal function 3, 4.
- Diagnosis is typically made through a combination of clinical presentation, laboratory tests, and kidney biopsy, although biopsy is not always necessary 3.
- The extent of cast formation, tubular atrophy, and interstitial fibrosis can be assessed through kidney biopsy, which can help predict renal prognosis 3.
Treatment and Management
- Treatment of myeloma kidney involves reducing serum free light chain levels, which is key to recovering renal function 3, 4.
- Chemotherapy, such as bortezomib and dexamethasone, can be effective in reducing free light chain levels and improving renal function 3, 5.
- Extracorporeal removal of light chains, such as hemodialysis with high-flux or high-cut-off membranes, may also be used in combination with chemotherapy to improve renal function recovery 3.