The study, published in the Archives of Internal Medicine, focuses on a group of 11 patients, ranging in age from 61 years old to 89 years old, whose kidneys suddenly shut down after using enemas containing sodium phosphate.

"Their use should be limited to low-risk patients only," wrote Dr. Yaacov Ori and his colleagues from the Rabin Medical Center in Petah-Tikva, Israel.

Enemas to relieve constipation work by drawing water into a person's gut to soften the stool, which allows it to pass more easily.

According to the report, ten of the patients used the enema for constipation, and the other to prepare for a proctoscopy procedure. The majority received the standard 250 milliliter dose, and seven had some trouble with their kidneys before using the enema.

Within one day of using the enema, the authors write, most of the patients had low blood pressure, low calcium levels and elevated phosphate levels in their blood.

Five of the patients died and three of the surviving six required prolonged hospital stays.

In an email to Reuters Health, Ori said once the sodium phosphate is absorbed into a person's body, "it overwhelms the system, and the kidneys cannot deal with this quantity."

Dr. Markus Bitzer, a nephrologist at the University of Michigan, told Reuters Health that it's up to the kidneys to remove the excess salt, but many older people suffer from chronic kidney disease and do not drink enough fluids.

"The kidney tries to eliminate the salt, but what happens is the salt in the kidney system becomes concentrated," said Bitzer.

"Over a few days or weeks it can cause the formation of crystals, and they then cause renal failure," he said.

Concerns over sodium phosphate enemas are not new.

Bitzer said people were aware of possible problems with the enemas and kidneys possibly as far back as the mid-1990s. He added that a few years ago the University of Michigan stopped using the mixture in enemas for their patients.

Instead, Bitzer said, their patients receive a mixture created by their pharmacists of either a special soap or sugar.

In his email, Ori told Reuters Health that patients should not use the enemas if "they have tendency for atonic bowel (patients in nursing homes, taking medications with anti-cholinergic effects, patients with colitis), patients with renal failure, and more."

Bitzer said he would not recommend them for younger patients either, because they may have undiagnosed kidney disease.

He said one way to avoid using the enemas is for a person to focus on their diet.

"Constipation is something that has to do a lot with our diet," said Bitzer. "I emphasize to all of my patients that are constipated to increase their fiber and to make sure they're getting enough fluid intake per day."

Fleet, the company that licensed the enemas used by the patients in the new report, told Reuters Health in a statement, that Dexxon Ltd. manufactured and sold the products in Israel.

"Fleet just became aware of the study. It was not involved in the study or consulted on the report. Fleet is in the process of evaluating the report, contacting the authors of the study, communicating with Dexxon, and communicating with the appropriate regulatory authorities," the statement continued.

SOURCE: bit.ly/zocSOf Archives of Internal Medicine, online February 13, 2012.

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