Cystatin C: A possible sensitive marker for detecting potential kidney injury after computed tomography coronary angiography

OBJECTIVES: Cystatin C (CyC) has recently been recognized as a sensitive marker for potential renal dysfunction. We investigated the role of CyC for evaluating potential kidney injury after computed tomography coronary angiography (CTCA). METHODS: The CyC, serum creatinine (sCr), estimated glomerular filtration rate (eGFR), and blood urea nitrogen (BUN) levels were evaluated before and 1 day and 1 week after the procedure in 140 patients with preserved renal function referred for CTCA. The amount of unrestricted oral fluid intake was measured for 24 hours after CTCA. The relationship between the amount of oral fluid intake and the changes in each renal marker was compared. RESULTS: A strong correlation was observed between oral fluid volume and the changes in CyC (r = -0.80, P < 0.0001) as well as the changes in sCr (r = -0.54, P < 0.0001) and eGFR (r = 0.57, P < 0.0001), but a weak correlation was observed between oral fluid volume and the changes in BUN (r = -0.22, P = 0.03). A progressive rise in a mean level of CyC was observed. The percentage of diabetic history was greater (73% vs 40%, P < 0.001) and oral fluid volume was lower (1142 mL vs 2114 mL, P < 0.0001) in patients with a rise in CyC but without one in sCr than in those showing a rise in neither CyC nor sCr at 1 day postprocedure. Seventy-four (80%) of 92 patients with a rise in CyC at 1 day postprocedure showed a recovery to the baseline sCr levels at 1 week postprocedure, but only 26 (28%) showed a recovery to the baseline CyC levels at 1 week. CONCLUSIONS: Cystatin C is a more sensitive marker than sCr in evaluating the effects of oral fluid volume on renal function and in detecting potential kidney injury, especially in diabetic patients after CTCA.