Urinary MCP-1/creatinine in Henoch–Schönlein purpura and its relationship with nephritis

Background Monocyte chemotactic protein-1 (MCP-1) plays a direct role in the infiltration of macrophages and monocytes during the early stages of Henoch-Schönlein purpura (HSP) nephritis. The aim of this study was to compare the urinary MCP-1/creatinine levels in children with and without HSP nephritis and determine if they are associated with the severity of renal lesions. Methods We included 77 patients with HSP and 25 healthy control children. Levels of serum creatinine, urinalysis, and 12-h proteinuria assessments were performed. Urinary MCP-1 levels were determined by ELISA. Results Fifty-seven patients had nephritis (74 %). Urinary MCP-1/creatinine levels were significantly higher in patients with HSP nephritis (median, 653 pg/mg) compared to those with HSP without nephritis (median, 269 pg/mg) or healthy children (191 pg/mg). In addition, higher MCP-1/creatinine levels were observed in HSP patients who had renal biopsy (median, 1,412 pg/mg) in comparison to HSP patients without renal biopsy (median, 302 pg/mg). The urinary MCP-1 cut-off value of 530 pg/mg could be used to distinguish patients who undergo renal biopsy with a sensitivity of 81 % and specificity of 77 %. Conclusions Urinary MCP-1/creatinine levels are elevated in the early stages of severe HSP nephritis and can be used as a biomarker for HSP nephritis.