Nephrologists warn of kidney failure induced by drugs, medical procedures

The number of people with kidney disease is increasing, but experts say that not all cases can be blamed on increasing rates of obesity, diabetes and hypertension that are so often cited as likely causes.

The things physicians do as part of patient care also might inadvertently cause damage, and physicians need to be aware of this possibility, according to a session at the Renal Week 2007, the American Society of Nephrology's 40th Annual Meeting and Scientific Exposition in San Francisco last month.

"When you talk about drugs having toxicity, it's very common for that negative effect to be in the kidney," said Glen Markowitz, MD, associate professor of clinical pathology at Columbia University in New York. "We need to educate physicians on recognizing these toxicities."

And some of the newly discovered causes of iatrogenic kidney disease are fairly common parts of medical practice.

For example, Dr. Markowitz presented information on the kidney failure that can result from ingesting oral sodium phosphate solution to prepare the bowels for colonoscopy or surgery. Several studies, including some he wrote, have documented several dozen cases, particularly among older women taking hypertension medications or nonsteroidal anti-inflammatories. The Food and Drug Administration warned of this adverse event last year and called for these preparations not to be used in those at high risk for kidney failure. Ample hydration can help make this complication less likely.

Additional areas of concern

Nephrologists also are concerned about bisphosphonates used to treat osteoporosis, Paget's disease and bone metastases associated with some cancers. These drugs may damage the kidneys, although data suggest that this scenario is most likely when the drugs are used at high doses in patients who already have some kidney problems.

"To get toxicities, you really have to [take] more than the approved amount or [take the drug] more frequently than is approved. Having some decreased renal function also makes it more likely," said Daniel W. Coyne, MD, professor of medicine in the renal division at Washington University School of Medicine in St. Louis. "In patients with decreased kidney function, you should consider whether you're administering the right dose or whether you want to use these drugs."

Experts urge assessment of a patient's kidney before starting these drugs, particularly if the medicine will be taken in large quantities. Also, doctors should consider discontinuing them if problems develop.

By far the most controversial possibility emerging from the data is that newer contrast agents for various scanning modalities such as computed tomography and magnetic resonance imaging might be toxic to the kidneys. Older iodine-based contrast agents have long been recognized as possible culprits in this adverse event, but newer gadolinium-based ones may also have this affect, particularly for patients who already have some kidney problems.

"Some [studies] show no potential for risk, while others clearly show that there is a risk for this complication. It is my conclusion that gadolinium may cause further kidney damage in cases where the recipient has prior kidney disease," said Roger Rodby, MD, a nephrologist and associate professor of medicine at Rush University Medical Center in Chicago.

Experts are recommending caution when using gadolinium in this population. Not only can it cause further damage to the kidneys, in some cases it can trigger a very painful skin condition.

It's unknown how much kidney disease is caused by medical care itself. Meanwhile, the rates of this disorder are increasing and expected to continue to do so.

This phenomenon is primarily explained by the increasing rates of obesity, diabetes, hypertension and the aging of the population.

According to the latest numbers from the United States Renal Data System, the prevalence of end-stage renal disease will grow by 60% between 2005 and 2020.

These projections were presented at last month's meeting. Also, a study in the Nov. 7 Journal of the American Medical Association found that from 1999 to 2004 more than 13% of the population had some form of chronic kidney disease. These figures marked an increase from the 10% documented from 1988-1994. That study did not count those who were at the end stages.