Multiple myeloma is a cancer originating in plasma cells, a type of white blood cell located within the bone marrow. These abnormal plasma cells multiply uncontrollably and produce large quantities of dysfunctional proteins, known as monoclonal proteins or M proteins, instead of healthy antibodies that fight infection. These abnormal proteins circulate throughout the bloodstream and can accumulate in various organs, leading to a range of complications. Kidney failure is a serious complication of multiple myeloma, affecting many patients.
How Multiple Myeloma Harms Kidneys
Multiple myeloma can impair kidney function through several mechanisms. The most common cause is the overproduction of abnormal proteins called monoclonal light chains, also known as Bence Jones proteins. These light chains are filtered by the kidneys, but their excessive presence overwhelms the kidney’s reabsorptive capacity. The light chains then combine with Tamm-Horsfall mucoprotein, forming insoluble casts that obstruct the kidney tubules. This blockage, known as myeloma kidney or cast nephropathy, directly damages kidney tissue and leads to a decline in function.
Elevated calcium levels in the blood, or hypercalcemia, also contribute to kidney damage. Myeloma cells stimulate bone breakdown, releasing excess calcium into the bloodstream. High calcium concentrations directly impair the kidney’s ability to filter waste and can lead to calcium deposits within the kidney tissue, worsening dysfunction.
Amyloidosis involves the deposition of abnormal protein fragments, called amyloid fibrils, within various organs, including the kidneys. These amyloid deposits can accumulate in the glomeruli, the kidney’s filtering units, disrupting their structure and hindering their ability to effectively filter blood. While less common than cast nephropathy, amyloidosis can lead to significant kidney impairment.
Other factors can further compromise kidney health. Dehydration, often due to increased calcium levels or decreased fluid intake, reduces blood flow to the kidneys, intensifying damage. Certain medications, including some non-steroidal anti-inflammatory drugs (NSAIDs), specific antibiotics, and contrast agents used in imaging studies, can be toxic to the kidneys and worsen existing impairment. Infections can also place additional stress on vulnerable kidneys, contributing to a decline in function.
Recognizing Kidney Issues
Recognizing kidney issues in multiple myeloma can be challenging, as some symptoms may overlap with the underlying cancer. General indicators of kidney dysfunction include increased fatigue, unexplained weight loss, and loss of appetite. Individuals might also notice swelling in the face, hands, or feet from the body retaining excess fluid.
Changes in urination patterns are common, such as urinating more frequently, especially at night, or producing frothy urine due to increased protein content. Some individuals may even observe blood in their urine. Other signs can include dry, itchy skin, muscle cramps or weakness, poor concentration, and difficulty sleeping.
Diagnosis of kidney problems in multiple myeloma involves laboratory tests. Blood tests measure serum creatinine levels and calculate the estimated glomerular filtration rate (eGFR) to assess kidney function. Electrolyte levels are also checked to detect imbalances.
Urine tests include a 24-hour urine collection to quantify total protein excretion and identify Bence Jones proteins (monoclonal light chains) through urine protein electrophoresis. In some cases, a kidney biopsy may be performed to examine kidney tissue. This helps determine the specific type and extent of kidney damage, guiding targeted treatment.
Treatment Approaches
Treating kidney failure caused by multiple myeloma primarily focuses on addressing the underlying cancer to reduce harmful protein production. Chemotherapy regimens, often including proteasome inhibitors like bortezomib, are frequently used to rapidly suppress myeloma cell activity. These medications can be administered alone or in combination with other agents such as cyclophosphamide and dexamethasone.
Targeted therapies and immunotherapies specifically attack myeloma cells or boost the body’s immune response against them. These treatments aim to reduce abnormal plasma cells, decreasing toxic light chains circulating in the blood. A stem cell transplant, typically an autologous transplant using the patient’s own cells, may be considered for eligible individuals after initial chemotherapy to achieve deeper, more durable remission.
Beyond treating the myeloma, specific interventions manage and support kidney function. Maintaining adequate hydration, often through intravenous fluids, helps dilute light chains and maintain urine flow. High blood calcium levels, if present, are managed with medications like bisphosphonates or denosumab, which reduce bone breakdown and lower calcium concentrations.
Patients should avoid nephrotoxic medications, such as NSAIDs, certain antibiotics, and radiocontrast agents, to prevent further kidney damage. For severe kidney failure, dialysis may be necessary to remove waste products and excess fluid from the blood. High-cutoff hemodialysis, which uses specialized filters to remove light chains more effectively, or plasma exchange, can sometimes rapidly reduce circulating light chains, offering a chance for kidney function recovery.
Managing Life with Multiple Myeloma Kidney Failure
Living with multiple myeloma and associated kidney issues requires ongoing management to maintain health and quality of life. Regular monitoring of kidney function involves periodic blood tests to assess serum creatinine and eGFR, as well as urine tests for protein levels. These tests help track kidney damage or recovery and guide treatment adjustments.
Dietary considerations play a role in managing kidney health. Depending on the degree of kidney impairment, individuals may need to limit their intake of sodium, potassium, and phosphorus, as damaged kidneys struggle to excrete these minerals. A registered dietitian can provide personalized guidance to ensure adequate nutrition while adhering to dietary restrictions.
Adherence to prescribed medications is also crucial, as consistent treatment of the underlying multiple myeloma and any related complications can help preserve kidney function. Patients should discuss any over-the-counter medications, supplements, or herbal remedies with their healthcare team to avoid potential kidney-damaging interactions.
A multidisciplinary care team, including hematologists, nephrologists, and dietitians, provides comprehensive support. This collaborative approach ensures all aspects of the patient’s condition are addressed, from cancer treatment to kidney-specific care and nutritional needs. Patient education and access to support resources also empower individuals to actively participate in their long-term health management.