Expression of serum cystatin C （Cys C）and urinary N-acetyl-beta-D.glucosaminidase（NAG） in elderly diabetes patients with early renal injury

Objective To explore the expression of serum cystatin C （Cys C）and urinary N-acetyl-beta-D- glucosaminidase（NAG） in elderly diabetes patients with early renal injury. Methods 127 cases of diabetes were divided into the pure diabetic group, early diabetic nephropathy group, diabetic nephropathy, and the other 38 cases of healthy persons as the control group. The serum Cys C, and serum Creatinine （Scr） concentration by automatic biochemical analyzer were detected,urinary NAG activity was detected by colorimetric determinate,24 hours albumin excretion rate （UAER/24h）was tested. Results The serum Cys C, urinary NAG, Scr, UAER/24h showed an increasing trend in four groups of patients respectively, the difference was statistically significant（ P 〈 0.05 or P 〈 0.01 ）. The serum Cys C and urinary NAG showed a positive correlation with Scr and UAER/24 h respectively. The accuracy, sensitivity, specificity of serum Cys C in diagnosis of early diabetic nephropathy group were 86.8%, 76.1% ,97.8% respectively, The accuracy, sensitivity, specificity of NAG in diagnosis of early diabetic nephropathy group were 83.5 %, 71.7% ,95.6%. Conclusion The serum Cys C and urinary NAG could sensitively reflect early elderly diabetic renal damage,which were the ideal endogenous indicators of glomerular filtration rate（GFR）. Key words: Diabetic nephropathy;  Serum cystatin C ;  N-acetyl-beta-D-glucosaminidase