Chemotherapy is a primary treatment for many types of cancer, aiming to destroy rapidly dividing cancer cells. While effective, these powerful medications can also affect healthy cells and organs. The kidneys are particularly susceptible to potential side effects from chemotherapy.
How Chemotherapy Affects Kidneys
The kidneys play a crucial role in filtering waste products and drugs from the bloodstream, including chemotherapy agents. As they process these medications, kidney damage, known as nephrotoxicity, can occur. Chemotherapy drugs can directly harm kidney cells, leading to cellular disruption and dysfunction. This direct cellular damage can manifest as acute tubular necrosis, where the kidney’s filtering tubules are injured.
Some chemotherapy agents can also lead to the formation of crystals within the kidney tubules, obstructing the filtration process. Chemotherapy can trigger inflammatory responses within the kidneys, contributing to tissue damage. Tumor lysis syndrome is an indirect cause of kidney injury, occurring when a large number of cancer cells break down rapidly, releasing their contents into the blood. This sudden release overwhelms the kidneys with substances like uric acid and phosphates, which can crystallize and block the tubules, potentially leading to acute kidney injury.
Chemotherapy Drugs Linked to Kidney Damage
Several chemotherapy drugs and drug classes are recognized for their potential to cause kidney damage. Platinum-based drugs, such as cisplatin and carboplatin, are nephrotoxins. Cisplatin can accumulate in kidney cells, leading to direct injury to the renal tubules, inflammation, and oxidative stress. This damage is a significant concern that can limit the drug’s dosage. Carboplatin also carries a risk of kidney injury, especially at higher doses or in patients previously exposed to cisplatin.
Methotrexate can cause kidney damage, particularly with high-dose therapy. Its mechanism involves the formation of crystals in the kidney tubules, impeding their function. Ifosfamide, an alkylating agent, is also associated with kidney toxicity, primarily due to its metabolite, chloroacetaldehyde. This metabolite can induce dysfunction in the proximal tubules of the kidneys, affecting their ability to reabsorb essential substances. Other antimetabolites and antitumor antibiotics have also been linked to kidney damage.
Identifying and Addressing Kidney Issues
Monitoring for specific signs and symptoms helps identify potential kidney problems during chemotherapy. Patients might experience swelling in their hands, ankles, or feet, changes in urination frequency or amount, or persistent fatigue. Other indicators include high blood pressure, nausea, vomiting, or a metallic taste in the mouth. Patients should communicate any new or worsening symptoms to their healthcare team promptly.
Kidney function is routinely monitored through blood tests such as creatinine and blood urea nitrogen (BUN). Glomerular filtration rate (GFR), an estimate of how well the kidneys are filtering, is also assessed. Urinalysis can detect protein or blood in the urine, indicating kidney damage.
Managing kidney damage involves maintaining adequate hydration, often with intravenous fluids, to help flush chemotherapy byproducts. Dosage adjustments of chemotherapy drugs may be necessary, and protective medications can be administered. For tumor lysis syndrome, medications may be used to manage uric acid levels.
Factors Increasing Kidney Risk
Several factors can increase the risk of kidney damage during chemotherapy. Individuals with pre-existing kidney conditions face a higher risk due to reduced kidney reserve capacity. Older age is another contributing factor, as kidney function naturally declines with age. Dehydration, whether due to inadequate fluid intake, nausea, vomiting, or diarrhea from treatment, can stress the kidneys and increase susceptibility to damage.
Chronic medical conditions like diabetes and hypertension also elevate the risk of chemotherapy-induced kidney injury. These conditions can independently affect kidney health over time, making the kidneys more vulnerable to the additional stress of chemotherapy. Concurrent use of other nephrotoxic medications, such as certain antibiotics or non-steroidal anti-inflammatory drugs, can further compound the risk. Healthcare providers consider these factors when planning treatment to minimize potential harm to the kidneys.