The Role of Serum Symmetric Dimethylarginine (SDMA) As Endogenous Biomarker of Renal Impairment in Correlation with Severity and Different Stages of Diabetic Kidney Disease

Abstract Background Diabetic Kidney Disease (DKD) is a major complication of Diabetes Mellitus (DM), contributing to increased morbidity and mortality. Early detection remains challenging, with standard markers like Glomerular Filtration Rate (GFR) and albuminuria showing limitations. Symmetric Dimethylarginine (SDMA) is a potential biomarker of renal function, cleared by the kidneys, that may offer better insights into DKD severity. Objective To evaluate the diagnostic utility of SDMA as an endogenous biomarker of renal impairment and its correlation with the severity and stages of DKD. Methods This cross-sectional study involved 150 diabetic cases (type 1 or type 2) who were stratified into late-stage (III-V) and early-stage (I-II) groups. SDMA levels were assessed using enzyme immunoassay, along with other renal function markers, and correlations with eGFR, proteinuria, and diabetes duration were analyzed. Results SDMA showed significant correlations with creatinine ( r = 0.785, p < 0.001), eGFR ( r = -0.598, p < 0.001), and urea ( r = 0.698, p < 0.001). SDMA levels significantly differed between early and late stages of DKD, with the highest levels observed in stage V (median 15.3 nmol/mL). ROC analysis demonstrated SDMA's ability to discriminate between early and late-stage DKD, with AUC values of 0.813 (Modification of Diet in Renal Disease (MDRD)) and 0.844 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI). Conclusion SDMA is a promising biomarker for assessing the severity and stages of DKD, correlating well with traditional renal function markers and offering high diagnostic accuracy.