The evaluation of gluomerular filtration rate in chronic kidney disease patients based on serum CysC

Objective To evaluate the applicability of several formulas for gluomerular filtoation rate (GFR) evaluation based on serum CystatinC （CysC） in patients with chronic kidney disease(CKD). Methods According to the method of laboratory appliance reseach, three hundred and four hospitalized CKD patients（162 males, 142 females , aged from 14-year-old to 80-year-old） in the First Affiliated Hospital of Zhengzhou University hospital dating from October 2010 to October 2011 were selected.Two-sample 99mTc-DTPA plasma clearance was determined as the standard GFR(sGFR) and the GFR based on simplized MDRD(GFR1) fomula, CKD-EPI CysC (GFR2) and CKD-EPI Cr-CysC fomula (GFR3). The results were compared with sGFR respectively. In addition, their correlation and the clinical significance were observed with Spearman correlation analysis, Bland-Altman agreement analysis and receiver operator characteristic（ROC） curve respectively. Results The correlation between the result of each GFR formula and sGFR was significant (r=0.690, 0.738, 0.724, P＜0.05), but some deviation existed when the estimated results were compared with sGFR in different CKD stages.When sGFR＜15 ml/(min·1.73 m2)（namely in CKD5）, GFR2［12.32（10.07-19.80）］ and GFR3［10.97（8.36-17.98）］ were significantly lower than that of sGFR［8.26（3.59-12.67）,Z=-3.959,P＜0.001; Z=-2.450, P=0.014］, while as GFR in CKD stage 2 ［GFR:60-89 ml/(min·1.73 m2) ］ and stage4［GFR:15-29 ml/(min·1.73 m2) ］，GFR1 was significantly lower than that of sGFR (t=-2.705，P=0.027；Z=-2.510，P=0.01).Furthermore, when GFR was in CKD stage 1［GFR≥90 ml/(min·1.73 m2)］ and stage3［GFR:30-59 ml/(min·1.73 m2)］，GFR2 was significantly lower than that of sGFR（t=4.270，P=0.004；t=2.762，P=0.011).In addition, when GFRs was applied as the standard diagnosis of CKD stage,the area under ROC of GFR1,GFR2 and GFR2 was 0.906，0.896 and 0.915 respectively. Conclusions The three GFR formulas are of diagnostic value in evaluating renal function of CKD patients, but the deviation also exists. In comparision, the CKD-EPI Cr-CysC fomula(GFR3) was more accurate than others in different CKD stages with larger ROC area in diagnosing CKD stage and the error can be reduced by combining serum Cr and CysC when evaluating kidney function.（Chin J Lab Med,2014,37:184-188） Key words: Renal insufficiency, chronic; Glomerular filtration rate; Cystatin C