TUESDAY, Oct. 18 (HealthDay News) -- A seemingly innocuous change in the way that parts of kidney dialysis machines are sterilized may have adverse health consequences, new research suggests.

A recently developed sterilization method called electron beam (e-beam) sterilization may have caused lower levels of platelets in the blood of dialysis patients, according to the study. Platelets help the blood clot. Low levels of platelets, a condition called thrombocytopenia, can lead to excessive bleeding.

The part of the dialysis machine that is sterilized by e-beam sterilization is called the dialyzer. The dialyzer is also sometimes called an artificial kidney. This is the part of the machine that filters the blood.

"Thrombocytopenia is not widely recognized as a potential dialyzer-related complication," wrote the study authors. But, after observing this complication in 20 people following dialysis, the authors wanted to find the cause.

"In this cohort of patients undergoing hemodialysis in two Canadian provinces in 2009-2010, the use of e-beam sterilized dialyzers was associated with significant thrombocytopenia following dialysis," they wrote.

Results of the study are published in the Oct. 19 issue of the Journal of the American Medical Association.

Complications related to dialyzers were more common in the 1960s because the material used to make dialyzers was not as biocompatible, or well-tolerated by the human body, as the material used today.

Dialyzers made from newer, more biocompatible substances significantly reduced immunological reactions, so much so that adverse device reactions to dialysis treatments are uncommon today, the authors said.

But, in 2009, it was discovered that a woman undergoing dialysis just before she was scheduled to have a kidney transplant had low levels of platelets following dialysis. Normally, blood is tested prior to dialysis, but not after. This particular woman's blood was taken before and after dialysis because of her scheduled transplant. Her platelet levels had dropped significantly enough that her transplant had to be cancelled.

Two days later, the woman returned for another dialysis treatment. Blood testing revealed that, again, her platelet levels had dropped during dialysis. After ruling out other potential causes, her doctors used a dialyzer that had been sterilized with gamma radiation instead of e-beam sterilization. Gamma radiation was used to sterilize dialyzers before a switch to e-beam sterilization occurred in 2009. When the gamma-radiation sterilized dialyzer was used, the woman experienced no post-dialysis drops in her platelet counts. She received a kidney transplant a month later.

The study authors then identified 19 more people who experienced drops in platelet levels after dialysis with an e-beam sterilized dialyzer. Once switched back to gamma-radiation sterilized dialyzers, no drop in platelets was seen. Two people were inadvertently exposed to an e-beam sterilized dialyzer again, and had a repeated drop in their blood platelet levels, reported the study.

The study authors then looked at about 1,700 people undergoing hemodialysis in British Columbia. Most were undergoing dialysis with e-beam sterilized dialyzers. The researchers found that e-beam sterilization was associated with a 3.6-fold increase in the risk of thrombocytopenia compared to non e-beam sterilized dialyzers.

Similar results were seen when they evaluated platelet levels of more than 400 dialysis patients in Alberta, the authors said.

It's not yet clear how e-beam sterilization might contribute to a drop in platelets, said Dr. Jonathan Himmelfarb, director of the Kidney Research Institute at the University of Washington in Seattle and author of an editorial in the same journal. In addition, he said, "We don't yet know if there are any clinical consequences for patients."

One thing is clear, he said. "Any systematic change in dialysis procedure should be systematically evaluated," he explained. "Although hemodialysis has become quite commonplace, we need to remember that it's still a complex medical procedure and we need to always be vigilant."

Dr. Robert Provenzano, vice chair of nephrology at St. John Providence Health System in Detroit, echoed Himmelfarb's concern. "We need to be cautious about how these products that our blood is exposed to are sterilized. Sterilization can alter the chemistry of the dialyzer. It may not be as benign as we thought," he said.

If you're undergoing hemodialysis, Provenzano said you can ask your center how the dialyzer is sterilized. If it's with e-beam sterilization, you can ask if it's affecting your platelets. But, centers can't reasonably screen every patient, he said. Centers using e-beam sterilization might screen some patients when there is a problem, he said. Also, some centers re-use dialyzers, which actually helps avoid some complications and is cost-effective, he said.

More information

To learn more about dialysis, visit the New York-based National Kidney Foundation.