Urinary neutrophil gelatinase-associated lipocalin as a marker of severe lupus nephritis in children

Abstract

More than 60% of children with systemic lupus erythematosus (SLE) develop lupus nephritis (LN). Neutrophil gelatinase-associated lipocalin (NGAL) is a protein secreted by leukocytes during inflammation and is overexpressed in the kidneys following ischemic and nephrotoxic damage. To study urinary and serum NGAL in children with SLE and investigate their possible role as markers of renal involvement. Methods Urinary and serum levels of NGAL were assessed in 33 children with active SLE (22 with and 11 without LN) and compared to 15 matched controls. Children with SLE had elevated urinary NGAL as compared to controls (P<0.001). Levels of urinary NGAL were higher in patients with LN than those without LN (P<0.001). In patients with LN, serum levels of NGAL were not significantly different from controls (P=0.4) and urinary NGAL correlated with the renal score of the Systemic Lupus Erythematosus Disease Activity Index (r=0.5, P=0.02) but not with serum NGAL (P=0.5). Urinary NGAL was significantly predictive of class III and IV LN (P=0.005) with 91% sensitivity and 70% specificity to levels ≥ 10.07 ng/mg creatinine. Conclusions Urinary NGAL is a sensitive marker of proliferative nephritis in juvenile SLE.