Nephrotoxicity is a rapid decline in kidney function following exposure to certain medications, chemicals, or toxins. The kidneys filter waste products from the blood and produce urine. When damaged, they can no longer effectively remove these waste materials or excess fluid from the body. This leads to a buildup of wastes and an imbalance in the body’s chemistry, with consequences ranging from temporary impairment to more lasting issues.
Common Causes of Kidney Damage
A wide array of substances can cause kidney damage, with medications being a prominent category. Certain prescription drugs, including antibiotics like aminoglycosides, chemotherapy agents such as cisplatin, and some antiviral medications pose a risk. Beyond prescription medications, common over-the-counter drugs can also contribute to kidney problems. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, are a frequent cause when used for extended periods or at high doses, as they can alter blood flow within the kidneys and cause harm over time.
Diagnostic procedures can also introduce substances that affect the kidneys. Intravenous (IV) contrast dyes, used to enhance visibility during imaging tests like CT scans, can sometimes lead to acute kidney injury. The risk is higher in individuals who already have some degree of kidney impairment or are dehydrated.
Exposure to substances in the environment or workplace is another potential source of nephrotoxicity. Heavy metals, including lead and mercury, are well-documented nephrotoxins that can cause significant kidney damage with prolonged exposure. Certain industrial solvents can also have a toxic effect on kidney tissue.
Signs and Symptoms
The signs of nephrotoxicity can vary in intensity. One of the most common indicators is a decrease in urine output. When the kidneys are unable to filter blood effectively, less urine is produced, which is a direct sign of impaired function.
As the body retains fluid, swelling (edema) occurs. This swelling is most apparent in the lower extremities, such as the legs, ankles, and feet, but can become more widespread. This fluid retention can also lead to shortness of breath if fluid accumulates in the lungs.
General feelings of illness are also characteristic of declining kidney function. Individuals may experience fatigue, weakness, and confusion or mental fogginess. Nausea is another frequent complaint, sometimes with a loss of appetite. These symptoms arise as waste products build up in the bloodstream.
Diagnosis and Monitoring
Healthcare professionals rely on specific tests to confirm a diagnosis of nephrotoxicity and to monitor the extent of the damage. Blood tests are fundamental in this process, measuring the levels of waste products that the kidneys are supposed to filter. Elevated levels of serum creatinine and blood urea nitrogen (BUN) are key markers, indicating that the kidneys are not clearing these substances from the blood efficiently.
Urine tests, or urinalysis, provide direct insight into the health of the kidneys. Analyzing a urine sample can reveal abnormalities that point to damage, such as the presence of protein or blood. The appearance of certain types of cells or cellular casts under a microscope can also help pinpoint the location and nature of the injury within the kidney.
In some situations, imaging studies may be used to visualize the kidneys’ structure. An ultrasound can help identify any blockages, such as kidney stones, or changes in the size and shape of the kidneys. For a more definitive diagnosis, a kidney biopsy may be performed. This procedure involves taking a small sample of kidney tissue to be examined under a microscope, which can reveal the specific type and severity of damage to the kidney cells.
Management and Prevention
The first step in managing nephrotoxicity is to identify and discontinue the substance causing the kidney damage. Once the offending drug or toxin is removed, the kidneys may begin to recover. Supportive care is then provided to help the body manage while the kidneys heal. This often involves carefully managing fluid intake and correcting any electrolyte imbalances that have occurred.
In more severe cases where kidney function is significantly impaired, dialysis may be required. Dialysis is a medical procedure that takes over the filtering function of the kidneys, removing waste products and excess fluid from the blood. This treatment is typically temporary, used to support the patient until their own kidney function improves.
Preventing nephrotoxicity involves several proactive measures. Staying well-hydrated helps the kidneys function properly and flush out potentially harmful substances. It is also important to take all medications as prescribed and to avoid long-term, high-dose use of over-the-counter pain relievers without medical supervision. Informing healthcare providers about all medications, including supplements, is another protective step before a procedure that involves IV contrast dye.