Relationship between pre-procedural microalbuminuria and renal functional changes after coronary computed tomography in diabetic patients

Background Diabetes is one of the risks for development of contrast-induced nephropathy (CIN). The percentage change in cystatin C (CyC), a recent new reliable marker for detecting subtle renal dysfunction, of ≥10% for 24 h after procedure is an independent predictor for developing CIN. Urinary microalbumin is one of the markers for preclinical nephropathy in diabetic patients. We investigated the relationship between pre-procedural urinary microalbumin and renal functional changes using CyC after coronary computed tomography angiography (CCTA) in diabetic patients. Methods Two hundred and six patients with diabetes scheduled for CCTA were enrolled. The serum creatinine and CyC levels were measured before and 24 h after CCTA. The percentage change in CyC (%CyC) and absolute change in estimated glomerular filtration rate (eGFR) from pre- to post-procedure were calculated. The pre-procedural urinary microalbumin was measured. The patients were classified into 2 groups as follows: group A comprised 93 patients with pre-procedural urinary microalbumin of ≥30 mg/g creatinine; and group B comprised 113 patients with one of <30 mg/g creatinine. Results The %CyC, fasting plasma glucose levels, and HbA1c were significantly greater in group A than in group B. The absolute change in eGFR was significantly less in group A than in group B. A significant correlation was seen between urinary microalbumin and %CyC (r = 0.49, p < 0.0001). Multivariate regression analysis revealed that pre-procedural urinary microalbumin and HbA1c were independent predictors for a %CyC ≥ 10% (OR: 1.030, 95% CI: 1.020–1.039, p = 0.008; and OR: 1.011, 95% CI: 1.007–1.016, p = 0.004, respectively). The optimal cut-off value of a pre-procedural urinary microalbumin level was 64 mg/g creatinine for predicting a %CyC ≥ 10% using receiver-operating characteristic curve analysis with a sensitivity, specificity, and area under the curve of 56%, 88%, and 0.72, respectively. Conclusions Renal functional changes should be paid attention to after CCTA, particularly in diabetic patients exhibiting elevated pre-procedural urinary microalbumin even though they indicate preserved eGFR.