Kidney failure is common in people with multiple myeloma (MM) and is usually caused by toxic effects of monoclonal light chains.
“Excess antibodies can damage the filtration apparatus of the kidney or the kidney tubule itself, resulting in kidney dysfunction or frank kidney failure,” said Michael Scola, MD, an oncologist and the director of Benign Hematology at Atlantic Hematology/Oncology in Morristown, New Jersey.
About 20% to 40% of people with MM have some degree of kidney impairment at the time of diagnosis. When people with MM develop kidney diseases, it is sometimes called myeloma kidney. This is associated with a higher risk of death.
Link Between MM and Kidney Disease
Kidney disease in MM is linked to the excess proteins – the monoclonal antibody light chains – that are produced by the myeloma cells. These proteins travel to the kidney, where they get deposited and bind to another type of protein called Tamm-Horsfall protein, which is usually present in urine.
The aggregation of the two proteins can form an undegradable cast that cannot be excreted through urine. This can block kidney tubules and glomeruli, leading to inflammation, atrophy, and scarring of kidney tissues.
MM can also affect the kidneys when it causes excess calcium in the blood – a condition called hypercalcemia. “Hypercalcemia causes the kidney to excrete excess fluid, directly damages the kidney, and can precipitate within the kidney as renal stones,” said Dr. Scola.
Symptoms of Kidney Disease in MM
Symptoms of kidney disease in patients with MM may be difficult to distinguish from MM symptoms. These may include things such as:
Loss of appetite
Pain, fluid, or stiffness in the joints
Nausea and headache
Making little urine
Fluid retention, causing swelling in the legs or feet
Weakness and fatigue
Urinary tract infection
Causes of Kidney Failure in MM
The major cause of kidney failure in people with MM is the overproduction of toxic immunoglobulin proteins. Other causes include:
Infections caused by MM or its treatment
High levels of calcium in the blood (hypercalcemia)
Low volume of circulating blood (hypovolemia)
Other medical conditions, such as diabetes and cardiovascular diseases
Use of some medications that can cause damage to the kidney
Risk Factors for Kidney Failure in MM
According to Dr. Scola, “The risk of kidney failure increases with the severity of the myeloma and duration of the disease prior to initiating treatment.”
Factors that may increase the chances of kidney failure in people with MM include:
Underlying chronic kidney disease
Age: 65-70 years is the median age for MM diagnosis, and older age is also a risk factor for kidney disease
Abnormal electrolyte levels
Use of non-steroidal anti-inflammatory drugs (NSAIDs)
Light chain myeloma, a subtype of MM that commonly permeates kidneys, damaging the renal tubules
Underlying medical conditions such as high blood pressure and diabetes
Doctors can order different tests if they suspect a person has MM, including:
Blood tests to reveal abnormal proteins produced by myeloma cells
Imaging tests, such as CT scans, X-rays, and MRIs
Bone marrow examinations
In cases where a person already diagnosed with MM shows signs and symptoms of kidney problems, their doctor will most likely require tests that involve collecting blood and urine samples to test for kidney function.
How to Counteract Kidney Failure
Although kidney failure is a common complication of MM, there are certain things people can do to reduce the likelihood of developing the condition, such as:
Working with their healthcare team to get the right treatment that will manage MM and its symptoms
Drinking enough water or getting fluid therapy to hydrate the body
Treating any other underlying medical condition
Taking medications as directed and keeping blood pressure optimally controlled
Asking their physicians about medications such as bisphosphonates that can help reduce bone damage and lower the level of calcium in the blood
Eating more fruits and vegetables and fewer foods with salt
Opting for kidney dialysis to take some strain off the organ
Notably, “the most serious manifestations of renal injury can be avoided by early recognition, involvement of a nephrologist, and initiation of appropriate supportive therapy,” Dr. Scola said.
There have been advancements in MM treatments. However, when it includes kidney problems, it becomes more challenging to treat. When the kidney is impaired, especially in people diagnosed with cancer, it increases mortality risk because the overall outlook for kidney recovery is still poor.
Other MM Complications
MM has different clinical manifestations and can lead to other health complications, such as:
Weakened immune system
Bone marrow failure
Bone problems, such as fractures and pain
Low red blood cell count (anemia)