A metabolic test to distinguish temporary and persistent renal graft dysfunction prior to transplantation

BACKGROUND: Despite donor organ shortage, many grafts are still discarded due to questionable quality. Functional evaluation of the graft prior to transplantation is compromised by the fact that many kidneys suffer from transient filtration failure early after preservation. We tried to circumvent this problem by using a non-invasive quantitative method to determine metabolic turnover of 13C-acetate in the isolated perfused kidney and then correlating this to graft function after actual transplantation. METHODS: Female porcine kidneys subjected to varying degrees of ischemic injury were put on a machine perfusion device. After injection of non-radioactive 13C-labelled acetate to the perfusate, its turnover by the citrate cycle was quantified by direct detection of 13CO2 in the gas outflow of the oxygenator with a mobile, high precision laser spectrometer. RESULTS: Even in the absence of urine production the method discriminates all kidneys that go on to resume function from those that do not resume function after actual transplantation. There is no overlap between the two groups. CONCLUSIONS: Potentially the 13 C turnover test offers an objective, quantitative and valuable adjunct in the toolbox for pre-transplant evaluation of questionable grafts.