Transplanting a pair of kidneys with limited function into one patient may offer one solution to short supply of donated kidneys

Transplanting a pair of kidneys with limited function into one patient can be just as successful as the standard procedure in which a patient receives a single kidney, according to new research at Wake Forest University Baptist Medical Center.

"Performing double transplants using kidneys that would otherwise be discarded may be one viable solution to the growing shortage of organs for transplantation," said Robert Stratta, M.D., co-author of a study presented at a meeting of the Central Surgical Association in Louisville, Ky.

During the 45-month study period, 19 patients underwent double transplants using organs from deceased donors that had been turned down by other centers because of limited function. The kidneys had marginal filtering capacity either because they were very small - from children - or they were from older adults who had begun to lose some kidney function.

"Patients who received double kidney transplants had similar short-term outcomes to patients who received single transplants," said Stratta. "In our short-term followup, we found that we could achieve excellent patient survival and kidney function using marginal kidneys if they are both transplanted into a single recipient."

The mean ages of the donors were 22 months for the pediatric kidneys and 65 years for the adult kidneys. Patient survival in both groups was 100 percent during a followup period of 20 months for those receiving adult kidneys and 10 months for those receiving pediatric kidneys. Kidney graft survival rates were 87 percent and 100 percent, respectively.

Stratta said a key to success is selecting patients with a lower risk of rejection and matching the estimated function of the kidneys to the needs of the recipient. People are normally born with two kidneys but require only about half the capacity of one kidney, depending on their age, size and other factors.

With a traditional single transplant, a donated kidney is placed in the abdomen and connected to the iliac artery and vein, major vessels in the abdomen. The failed kidneys are left in place and eventually shut down and shrivel in size.

With the double transplant surgery, two donated kidneys from a single donor are placed in the abdomen. In the case of very small kidneys from pediatric donors, organs are transplanted "en bloc," which means that the kidneys are left attached to their vessels and are transplanted as one unit.

While double transplants have been performed since the mid-1990s, they are not common. The significance of the current study was that it used kidneys from donors at the extremes of age. Stratta, a professor of surgery at Wake Forest University School of Medicine, said the use of dual transplants from these donors is part of an ongoing effort to learn more about which kidneys are suitable for transplant to make the best use of the limited number of organs from deceased donors.

About 67,000 people are on the national waiting list for a kidney transplant and only about 25 percent on the list receive a transplant each year.

In October 2002, the United Network for Organ Sharing (UNOS) implemented a new system for allocating higher-risk kidneys that were once considered unsuitable for transplantation and discarded. Referred to as expanded criteria donors (ECD), these include kidneys from deceased donors over age 60 or those over age 50 with health conditions such as high blood pressure, stroke or elevated levels of a protein called creatinine. Levels of creatinine, which is produced by muscle, are used to determine kidney function.

Wake Forest Baptist adopted a policy of routinely transplanting kidneys from ECDs and was able to double its annual transplant activity. Now, the center is one of the 50 most active kidney transplant centers in the country, according to the November issue of Nephrology News and Issues. About 40 percent of its deceased donor transplants are from ECDs. Waiting times for the ECD transplants average 20 months, compared to 30 months for standard transplants.

Stratta and colleagues have reported success using organs at the outer limits of acceptance criteria, which Stratta refers to as organs from "extreme" donors. These include donors older than 70 years, having high levels of creatinine, dying from cardiac arrest prior to organ donation, or prolonged storage time for the organ.