Research coming out of a kidney conference sheds light on the complexities of kidney donation and transplantation.

People with high blood pressure or diabetes may be advised not to donate a kidney.

Researchers are saying this weekend that donors with those conditions face a high risk of developing kidney problems themselves, and may need both kidneys in the long term.

The advisory is part of a set of new metrics, based on a donor’s health prior to donation, that can predict the lifetime incidence of kidney failure or end-stage renal disease (ESRD).

All this research was presented today at the ASN Kidney Week 2015 conference in San Diego, California.

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Dr. Hassan Ibrahim, a nephrologist at the University of Minnesota Medical Center, led the team that looked at the health impacts from diabetes and high blood pressure, or hypertension, in living kidney donors.

They found that people who have diabetes or high blood pressure have a two to four times higher chance of experiencing reduced kidney function compared to those who do not.

Overall, they found that for 88 percent of kidney donors, the lifetime risk of ESRD before donation was less than 1 percent.

Dr. Darla Granger, director of the St. John Transplant Specialty Center in Michigan, and a transplant surgeon, told Healthline that people with diabetes are ruled out as donors at her facility.

If a person has high blood pressure and wishes to donate a kidney, they may be considered on a case-by-case basis. Both conditions are top causes of kidney failure.

Granger said obesity is affecting the donor kidney pool and type 2 diabetes is a disease related to obesity.

“We as a society in general keep on getting fatter,” she said, “and the need for kidneys is alarming. There are so many more people waiting for kidneys than there are available donors.”

People with diabetes or hypertension who want to help another person by donating a kidney may not realize that they could wind up hurting themselves in the long run.

“You don’t want to create end-stage renal disease in someone because you took their kidney,” she said. But both hypertension and diabetes can be reversed with lifestyle and diet changes. Donors who can reform their lifestyles may be reconsidered, she said.

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Another study coming out of the conference states that kidneys from donors who have died are routinely being discarded.

This is particularly true of kidneys that become available on weekends, researchers said.

This highlights the need for better procedures to secure transplantable organs on weekends to help address the kidney shortage.

In the study, Dr. Sumit Mohan, a nephrologist from Columbia University, looked at the Scientific Registry of Transplant Recipients and compared deceased donor kidneys procured on Friday to Saturday with those that were taken on other days of the week.

The rate of securing kidneys from donors who have died is about the same throughout the week. Researchers found that about 89 percent of potential donor kidneys were procured on the weekend compared to 90 percent on other days.

However, researchers discovered that organs taken over the weekend were 20 percent more likely to be discarded than those taken on weekdays. They also found that the discarded kidneys were of higher quality than those discarded during the rest of the week.

“The day of the week when a donor kidney becomes available appears to impact the likelihood of procurement and its subsequent utilization, if procured,” Mohan said in a statement.

Dr. David Klassen, the chief medical officer at the United Network for Organ Sharing, told Healthline that the unnecessary waste of organs is an important issue confronting the transplant system.

“The research reported by Mohan and colleagues suggests that increased organ discard rates on weekends may be due to [issues with] transplant program resource availability,” he said.

“No actual estimates of resource availability were provided and it is possible that donors on weekends have clinical differences that might explain increased discard rates,” he said.

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Robert D. Sollars, an Arizona resident who received a donated kidney a year ago, said he does not believe kidneys are going to waste in large amounts.

“In certain areas it is possible, for whatever reason,” said Sollars, who received a kidney from a deceased donor at the Mayo Clinic Hospital in Phoenix.

“They are so desperate for kidneys, if one is donated and is viable, after necessary testing, it is used,” he said.

Granger, however, noted that not all kidneys are viable upon procurement. Some are extracted, and then found to be diseased.

One thing increasing the number of kidneys available is the use of healthy organs from older people — something that wasn’t done in the past.

Though there’s still a kidney shortage, Granger said the concept of organ donation is more widely accepted now. In her state, more than 50 percent of people are on the organ donor registry.

“When you look at the number of people waiting versus the available organs, it’s just not there,” Granger said. “That’s why we use living donors whenever we can.”