People who donate a kidney live just as long and are just as healthy as those with two kidneys, according to a new study by University of Minnesota researchers that is the largest ever done on the long-term health consequences of donation.

The study provides reassurance about the safety of kidney donation that could encourage more organ donations at a time when the need for such transplants is on the rise. Today there are 78,000 people on the kidney transplant list, and most will not survive the five- to seven-year wait for a kidney from a deceased donor.

"I'm hoping that this will alleviate the anxiety about living with one kidney," said Dr. Hassan Ibrahim, a university transplant surgeon and the lead author. "We can remove a lot of misconceptions."

The findings are in today's New England Journal of Medicine with an editorial that described the results as surprising and quite reassuring.

Ibrahim and his co-authors tracked down nearly all of the 3,700 people who had donated kidneys at the university's transplant center between 1963 and 2007. They found that the donors' life spans, and their risk for high blood pressure, diabetes, and, most important, kidney disease were the same as or better than those of non-donors of similar age, race and gender.

The result puts to rest lingering questions about the long-term health consequences for people who give a kidney to a family member, friend or stranger, said Dr. Bryan Becker, president of the National Kidney Foundation and a surgeon at the University of Wisconsin, who was not involved in the research. Now, he said, transplant surgeons "can give them confidence that their own health will not be compromised."

The number of people with kidney failure is growing at an astronomical rate -- 90,000 new cases per year, according to the National Kidney Foundation -- the result of an aging population beset with obesity, diabetes and other chronic conditions.

A living kidney donation is the best option for the 340,000 people with end-stage kidney disease who are tethered to dialysis machines for survival.

Living donors growing

The rate of kidney donation by living donors is growing, and now equals the number of kidneys from deceased donors, the more common source of organs. But compared with the demand, the number of both types of donor kidneys is quite small. In 2007 there were a total of 13,000 donated kidneys, about half from living donors.

Ibrahim and his co-authors were able to find 3,100 of the 3,698 people who had been donors at the university. In all, the donors' life spans and health status were average, compared with national health data bases, Ibrahim said, which confirms what a handful of much smaller studies had already found. What surprised him most was that they also had rates of high blood pressure and excess protein in their urine that were similar to those in the average population. Both have long been believed to be the result of living with only one kidney, he said.

Quality of life

The one area with a clear difference was quality of life, defined as physical and mental health, which was measured among a subgroup of 255 study subjects. For reasons that he could not explain, donors had a clear advantage, Ibrahim said.

Marv Jenkins, 75, of Woodbury, donated a kidney to his diabetic younger sister in 1978, at a time when living donation for diabetes patients was the Wild West of transplant medicine. He was one of the 255 donors in the subgroup who received more intensive tests.

At the time, he was so determined to be his sister's donor that he didn't think much about the long-term consequences, he said.

"One question my wife wanted me to ask was about coffee consumption. I drink a lot of coffee," he said. He asked, but his doctor brushed it aside.

"He said, 'The only thing I recommend that you discontinue is playing tackle football and horseback riding. But drink all the coffee you want,'" Jenkins said.

His sister lived for only two more years before she died as a result of a viral infection. But Jenkins said he has no regrets.

"I firmly believe that in the course of your life there are a limited number of issues that you have to confront in order to live at peace with yourself,'' he said. This was one. I wish she could have lived longer. But that wasn't in my hands."

Josephine Marcotty • 673-7394.