Correlation between Levels of Serum Creatinine and Erythrocytic Malondialdehyde(MDA) and Antioxidant Enzymes in Patients with Diabetic Nephropathy

Park, Keun Yong; Park, Sung Bae; Kim, Hyun Chul; Mun, Kyo Cheol; Kwak, Chun Sik; Kang, Mi Jeong; Jang, Jong Eog; Shin, Weon Seung

Abstract

Oxygen free radical activity is elevated in diabetes mellitus and has been implicated in the etiology of vascular complications and diabetic nephropathy is a serious microvascular complication in patients with IDDM. Despite intensive investigation, the pathophysiology of diabetic renal disease has not been fully elucidated. However, several clinical and experimental studies have suggested that endothelial dysfunction and changes of peritubular microcirculation might deteriorate renal function in patients with IDDM. We performed this study to examine the oxidative stress and correlation between levels of serum creatinine and erythrocytic MDA, SOD, catalase, GPX in IDDM patients with diabetic nephropathy. Twenty one patients with IDDM(diabetic duration >5 years) and persistent albuminuria(albumin excretion>1000mg/day) and 15 normal healthy controls were investigated prospectively for erythrocytic MDA(thiobarbituric acid assay) and antioxidant enzymes[SOD(Hyland et al.), catalase(Nelson and Kiesow), GPX(Palgia and Valentine)] and correlation to serum creatinine levels. Levels of erythrocytic MDA were significantly higher in patients with diabetic nephropathy than in normal healthy controls(p<0.05) and levels of erythrocytic antioxidant enzymes were significantly lower in patients with diabetic nephropathy than in normal healthy controls(p<0.05). There was no significant correlation between serum levels of creatinine and erythrocytic MDA in group 1(r=0.12, p>0.05) and group 2(r=0.12,p>0.05) but there was significant correlation between serum levels of creatine and erythrocytic MDA in group 3(r=0.96, p<0.05). There was no significant correlation between serum levels of creatinine and erythrocytic antioxidant enzymes in all patients with diabetic nephropathy groups(group 1, group 2, and group 3; p>0.05). We concluded that increased oxidative stress and decreased antioxidative defense mechanism might be factors in the initiation of diabetic nephropathy and the oxidative stress correlated with higher serum levels of creatinine(more than 5mg/dL)(p<0.05).