Utility of serum creatinine/cystatin C ratio in diagnosis of postrenal acute kidney injury

Background: in obstructive uropathy, despite a severe increase in the serum creatinine (cr) levels, only a mild cystatin c (cysc) increase was previously reported. therefore, we aimed to determine the availability of serum cr/cysc ratio in predicting postrenal acute kidney injury (aki). materials and methods: this was a cross-sectional study involving 61-adult patients with heterogeneous aki cases. patients with bilateral pelvicalyceal dilatation in renal sonography were considered as postrenal aki group (n = 15) and others were intrinsic aki group (n = 46). venous blood sampling for blood urea nitrogen, cr and cysc measurements were performed on admission. results: the mean age of study population was 66.3 ± 15.5 years; 38 (62%) of which were male. two groups were similar regarding age, gender, and comorbidities. cr/cysc ratio was significantly higher in postrenal aki group (6.9 ± 3.1 vs. 4.4 ± 2.1, p = 0.007). conclusion: we suggest that serum cr/cysc ratio seems to be a useful diagnostic tool for detection of postrenal aki cases, especially for the cases without definite hydronephrosis.