title: Potential of Serum and Urinary Matrix Metalloproteinase-9 Levels for the Early Detection of Renal Involvement in Children With Henoch-Schönlein Purpura.
abstract: BACKGROUND
  Matrix metalloproteinase-9 (MMP-9) is an enzyme implicated in the pathogenesis of renal diseases. Renal involvement is the principal cause of morbidity and mortality in children with Henoch-Schönlein purpura (HSP).
  
  
  OBJECTIVE
  The aim of this study was to evaluate whether serum and urinary MMP-9 levels are associated with renal involvement in HSP.
  
  
  METHODS
  We evaluated 40 children with HSP (patient group) and 27 healthy volunteer children (control group). The patient group was divided into two subgroups based on the presence or absence of nephritis. Nephritis was defined as the existence of hematuria and/or proteinuria. All anthropometric data, physical examination findings, blood pressure, and laboratory parameters were recorded. The serum and urine samples were analyzed to determine the MMP-9 levels three days after the initial phase of the disease.
  
  
  RESULTS
  The mean age was 7.65 ± 3.41 (range 2 - 16) years in the patient group and 9.52 ± 3.91 (range 2 - 16) years in the control group. Henoch-Schonlein purpura nephritis (HSPN) was identified in eight patients. There was no significant difference in the serum MMP-9 levels between the HSPN subgroup and the controls (P > 0.05). However, there were significant differences in the urinary MMP-9 levels between the HSP subgroup and the control group (P < 0.05), with the urinary MMP-9 levels being significantly higher in patients in the HSP subgroup (P = 0.001). Further, the urinary MMP-9 levels were significantly higher in the patients with nephritis than in the patients without nephritis (P = 0.001) and the controls (P = 0.001). The optimal cut-off point (sensitivity; specificity) of the urinary MMP-9 level for the diagnosis of HSPN was 94.7 pg/mL.
  
  
  CONCLUSIONS
  The levels of MMP-9 in the urine were remarkably high in patients with HSPN. This non-invasive marker may therefore be an important indicator for the early diagnosis of nephritis in children with HSP.
authors.affiliation: Department of Pediatrics, Bagcilar Training and Research Hospital, Istanbul, Turkey.
authors.forename: Meltem
authors.initials: M
authors.lastname: Erol
authors.affiliation: Department of Pediatrics, Bagcilar Training and Research Hospital, Istanbul, Turkey.
authors.forename: Ozgul
authors.initials: O
authors.lastname: Yigit
authors.affiliation: Department of Pediatric Nephology, Koc University Hospital, Istanbul, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Tasdemir
authors.affiliation: Department of Pediatrics, Bagcilar Training and Research Hospital, Istanbul, Turkey.
authors.forename: Ozlem
authors.initials: O
authors.lastname: Bostan Gayret
authors.affiliation: Department of Pediatrics, Bagcilar Training and Research Hospital, Istanbul, Turkey.
authors.forename: Ovgu
authors.initials: O
authors.lastname: Buke
authors.affiliation: Department of Biochemistry, Bagcilar Training and Research Hospital, Istanbul, Turkey.
authors.forename: Aysegul
authors.initials: A
authors.lastname: Gunes
authors.affiliation: Department of Pediatrics, Bagcilar Training and Research Hospital, Istanbul, Turkey.
authors.forename: Sahin
authors.initials: S
authors.lastname: Hamilcikan
authors.affiliation: Department of Pediatric Rheumatology, Cerrahpasa Medical Faculty, Istanbul University, Istanbul, Turkey.
authors.forename: Ozgur
authors.initials: O
authors.lastname: Kasapcopur
keywords: Henoch-Schönlein Purpura; Henoch-Schönlein Purpura Nephritis; Matrix Metalloproteinase-9