Abstract:

Objective To establish a magnetic particle chemiluminescence for the determination of urinary type Ⅳ collagen（ⅣC）,and to investigate the role of urinary ⅣC in membranous nephropathy（MN）. Methods A magnetic particle chemiluminescence was established for the determination of urinary ⅣC. The performance （determination limit,linear range,accuracy,precision,recovery rate and sensitivity） was verified. The receiver operating characteristic （ROC）curve was used to evaluate the efficiency of urinary ⅣC in the diagnosis of MN. The urinary ⅣC levels of 274 patients with chronic kidney disease（CKD） was determined,and the changes of urinary ⅣC levels in different pathological types and different CKD stages were compared. Results Urinary ⅣC was determined by magnetic particle chemiluminescence,and the standard curve was drawn,with the equation of Y= 42.802X²+10 626X-10 856 （r²=0.999）. The lower determination limit was 1.48 ng/mL,the within-run coefficients of variation（CV） for low-level, middle-level and high-level samples were 4.22%,8.16% and 3.46%,and the between-run CV for low-level and middle-level samples were 18.23% and 17.61%. The average recovery rate was 97.0%. ROC curve showed that the area under curve （AUC） of urinary ⅣC in the diagnosis of MN was 0.875 [95% confidence interval （CI）0.837-0.913]. The optimal cut-off value of urinary ⅣC was 4.15 ng/mL. The sensitivity was 79.0%,and the specificity was 86.7%. Compared with healthy control group,the levels of urinary ⅣC in MN group,mesangial proliferative glomerulonephritis（MsPGN） group and non-membranous nephropathy （N-MN）group were increased（P<0.01）. Compared with N-MN group,the levels of urinary ⅣC in MN group and MsPGN group were increased （P<0.01）. For CDK staging,there was a statistical significance in urinary ⅣC level between CKD1 group and CKD2,CDK3,CDK4 groups（P<0.01）. There was no statistical significance between CKD1 and CKD5 groups （P>0.05）. Conclusions Magnetic particle chemiluminescence for the determination of urinary ⅣC is simple,reliable and inexpensive,and it plays a role for the diagnosis and prognosis of MN.

Key words: Type Ⅳ collagen;, Urine, Magnetic particle chemiluminescence, Performance evaluation, Membranous nephropathy, Mesangial proliferative glomerulonephritis