Cut‐off values for serum matrix metalloproteinase‐9: Is there a threshold to predict renal involvement for Henoch–Schonlein purpura in children?

Abstract

To clarify whether the level of matrix metalloproteinase-9 (MMP-9), tissue inhibitor matrix metalloproteinase-1 (TIMP-1) or the ratio of MMP-9/TIMP-1 was associated with the renal involvement in Henoch-Schonlein purpura (HSP); and to explore whether there existed early diagnostic measure for HSP nephritis (HSPN). Sixty-six patients with HSPN, 68 patients with HSP and 60 healthy children (control group) were enrolled into our study. Serum and urine samples before treatment were collected for detection. Compared with the HSP group and control group, serum MMP-9, TIMP-1 and ratio of MMP-9/TIMP-1 in the HSPN group were significantly higher (P<0.05 and P<0.01, respectively). Urine MMP-9, TIMP-1 and ratio of MMP-9/TIMP-1 in the HSPN group were obviously higher than those of the control group (P<0.05) and the HSP group (P<0.05). Receiver-operator curve (ROC) analysis was performed to obtain the area under the curve (AUC) and the AUC and its 95% confidence interval (CI) of serum MMP-9 were 0.97 and 0.95-0.99, respectively. The optimal cut-off point (sensitivity; specificity) of serum MMP-9 for diagnosing HSPN was 179.79 mg/L (0.96; 0.88). Levels of MMP-9, TIMP-1 and ratio of MMP-9/TIMP-1 in serum and urine were remarkably high in the patients with HSPN, but the serum MMP-9 was more sensitive. Serum MMP-9 may be associated with the occurrence and development of renal involvement in HSPN and become an important indicator for early diagnosis of HSPN.