UK transplant surgeons could be the first in the world to use a new test aimed at extending the availability of useful organs. The test, developed by scientists at Glasgow University, enables donor kidneys to be tested for their "biological" rather than their chronological age.

UK transplant surgeons could be the first in the world to use a new test aimed at extending the availability of useful organs.

The test, developed by scientists at Glasgow University, enables donor kidneys to be tested for their "biological" rather than their chronological age.

This will allow surgeons to use an organ from a healthy 70-year-old knowing that it is in better shape than one from an unhealthy 50-year-old, which would have been expected to function better because it was younger.

By comparing genetic signs of biological ageing with biochemical markers related to kidney function, they will be better able to predict how long grafted kidneys will last before they in turn need replaced.

The scientists' goal is to whittle down the time it takes to turn around the test results so they can be applied while the kidney is still viable.

But they are also looking ahead to similar tests being available to everyone as an MoT for the body, monitoring the ageing process so that medical intervention or lifestyle improvements can slow down the clock.

Dr Paul Shiels, of the university's department of surgery, who led the research, said: "There are approximately 3000 kidneys available for the 12,000 patients on the European Transplant Organisation waiting list, so many will die without getting a transplant.

"They are trying to use older and more marginal donors to meet the shortfall in organs and the outcome is often not so good. We wanted to find out why in some circumstances an older organ can function better than one from a younger donor.

"Until now the best indicator has been the chronological age of the donor, but we now think the biological age of the organ is more important.

"If you get someone from a high-deprivation area, such as Calton in Glasgow where the average male life expectancy is 54, then the organ may be biologically more aged.

"We can get an indication of how likely it is to reject, or how likely the patient is to suffer a cardiac-related event. These are tied in to kidney function.

He added: "We wanted to find out how you age biologically. You can apply it to disease - what is it that diseases do to your biological clock..

"At the moment we can do the test in four hours. We hope to get this time further reduced before the kidney is installed. The test could be in use within a year."

At the heart of the new test are the telomeres, the tails at the end of each chromosome. These shrink with age, but the rate of shrinkage depends on the individual's state of health. The scientists used an established genetic test, PCR, to measure shortening of the telomeres in donor kidneys prior to transplant.

A number of genetic markers of shortened telomeres - together with the donor's age - were compared with levels of serum creatinine, a sign of reduced kidney function.

The scientists reported in the journal Aging Cell that one genetic factor in particular, CDKN2A, showed a strong link with raised serum creatinine levels, even more so than the age of the donor.

This meant that the "biological age" of the kidney was a more reliable indicator of its health than the patient's chronological age.