Can the kidney volume help to differentiate the types of rejection before biopsy?

Background: The aim of this study was to use the volume of the graft as an adjunct tool for better decision making. Methods: Kidney transplanted patients with acute azotemia and documented volume and finally a biopsy were enrolled in this study‌. Graft volumes between rejected patients (antibody-mediated rejection {AMR} and cell - mediated rejection {CMR}) and ‌non rejected but azotemic patients were compared. Results: A total of 76 patients were enrolled in this study ‌(45 case and 31 control‌). 53.3% of the case group were‌ (AMR)‌ and 46.7% belonged to ‌(CMR). There was no difference between kidney volume according to age or sex. But the case group had a significantly bigger volume than controls (253.09 cm3 and 186.45 cm3; p< 0.001). In addition, there was a significant difference between the volumes of AMR kidneys with CMR and controls ‌(286.24+66.70‌, 224.08+76.79 and 186.95+39.92; P=0.003 and p<0.001, respectively), but not between CMR and controls ‌(P=0.067). A cutoff point of 200 cm3 was determined as rejection with sensitivity and specificity of 70% and a cutoff point of 250 cm3 could be used as AMR cut off with sensitivity of 76% and specificity of 70%. Conclusion: There was a significant difference in volume between rejection and control group and between AMR and CMR. So, kidney volume determination is an easy and valuable tool to help the clinician to have a more rapid and better decision making.