Symptoms and Causes of Kidney Damage in Multiple Myeloma Patients

Multiple myeloma, a type of blood cancer affecting plasma cells, frequently leads to kidney complications. When kidney function is impaired due to this condition, symptoms can vary significantly depending on the severity of the damage. In mild to moderate cases, patients may notice increased foaming in the urine, frequent nighttime urination (nocturia), and swelling around the eyelids—often one of the first visible signs of fluid retention caused by declining kidney function.

Recognizing Severe Kidney Impairment

In more advanced stages, kidney damage becomes significantly more dangerous. Individuals may experience oliguria (greatly reduced urine output) or even anuria (complete absence of urine production). These conditions are often accompanied by life-threatening metabolic imbalances such as hyperkalemia (high potassium), metabolic acidosis, and disturbances in calcium and phosphate levels. Without timely medical intervention, such complications can rapidly progress to acute or chronic kidney failure.

How Common Is Kidney Damage in Multiple Myeloma?

Renal involvement is alarmingly common among multiple myeloma patients—over 50% will show some degree of kidney dysfunction during the course of their illness. This makes early detection and management crucial for improving long-term outcomes and quality of life.

The Primary Cause: Light Chain Deposition

The most frequent cause of kidney injury in multiple myeloma is the buildup of monoclonal immunoglobulin light chains (also known as Bence Jones proteins), produced by malignant plasma cells. These abnormal proteins circulate in the bloodstream and are filtered by the kidneys, where they accumulate in the renal tubules. Over time, this accumulation causes direct toxicity to kidney cells, leading to tubular atrophy, interstitial inflammation, and progressive loss of kidney function—a condition often referred to as "myeloma cast nephropathy."

Other Contributing Factors

Besides light chain toxicity, several other factors can worsen or trigger kidney damage in these patients. Hypercalcemia, resulting from widespread bone destruction caused by myeloma lesions, can lead to calcium deposition in the kidneys and impair filtration. Additionally, certain medications used in treatment—such as nonsteroidal anti-inflammatory drugs (NSAIDs) or contrast dyes—may be nephrotoxic. Infections, dehydration, and high uric acid levels also place additional stress on already compromised kidneys.

Why Early Detection Matters

Identifying kidney problems at an early stage allows healthcare providers to implement protective strategies, including aggressive hydration, avoidance of nephrotoxic agents, and prompt treatment of underlying myeloma. Blood tests measuring creatinine and estimated glomerular filtration rate (eGFR), along with urine tests for proteinuria and light chains, are essential tools in monitoring renal health.

Understanding the link between multiple myeloma and kidney disease empowers patients and clinicians to act proactively. With proper management, it's possible to slow the progression of renal damage and improve overall prognosis for individuals battling this complex condition.