Association between serum magnesium level and contrast-induced nephropathy in patients undergoing percutaneous coronary intervention for acute coronary syndromes.

Contrast-induced nephropathy (CIN) remains a frequent and clinically significant complication following percutaneous coronary intervention (PCI), particularly in patients with acute coronary syndromes (ACS). In this study of 2,696 ACS patients undergoing PCI, we investigated the association between baseline serum magnesium (Mg) levels and development of CIN. CIN occurred in 27.2% of patients. Those who developed CIN were older and had higher rates of male gender, diabetes, STEMI, Killip class >1, and contrast volume, along with lower left ventricular ejection fraction. Serum Mg levels were significantly lower in the CIN group (1.826±0.208 vs. 2.091±0.183 mg/dL, p<0.001). In addition, patients were stratified into quintiles based on serum Mg levels and a clear stepwise increase in the incidence of CIN with decreasing Mg levels was demonstrated (Q5: 8.8%, Q4: 13.9%, Q3: 21.9%, Q2: 48.8%, Q1: 57.7%; p for trend <0.001). In ROC curve analysis, Mg level <1.92 predicted CIN with 72.1% sensitivity and 73.2% specificity. Mg <1.92 was found as an independent predictor of CIN in logistic regression analysis (OR: 2.992, 95% CI: 1.611-5.232, p<0.001). These findings suggest that serum Mg may serve as a novel biomarker for CIN risk stratification. Further studies are warranted to clarify the role of Mg screening and supplementation in reducing CIN risk among ACS patients.