Urinary and serum neutrophil gelatinase-associated lipocalin as a biomarker in Egyptian systemic lupus erythematosus patients: Relation to lupus nephritis and disease activity

AbstractBackgroundNeutrophil gelatinase-associated lipocalin (NGAL) is an excellent structural biomarker for the early diagnosis of acute kidney injury, prognosis, dialysis requirement and mortality in several common clinical scenarios.Aim of the workThe aim of this work is to detect the levels of both urinary and serum NGAL in SLE patients with and without lupus nephritis (LN) and to correlate their levels with renal biopsy class and disease activity.Patients and methodsThe study included 35 SLE patients; 22 with LN and 13 without as well as 30 matched controls. The SLE Disease Activity Index (SLEDAI) was assessed and the renal biopsy class determined. Urinary and serum levels of NGAL were assessed by ELISA.ResultsThe 35 patients had a median age of 30years and disease duration of 4years. They were 31 females and 4 males. The SLE patients had an elevated urinary NGAL (UNGAL) (median 19ng/ml, IQR 8–87) as compared to controls (median 2ng/ml, IQR 1–18.3) (p<0.006). Levels of UNGAL were higher in patients with LN than those without (p<0.023). In patients with LN, serum levels of NGAL were not significantly different from controls (p=0.6). The UNGAL level significantly correlated with the renal score of SLEDAI (r=0.54, p=0.001) but serum NGAL level did not (r=0.25, p=0.15). UNGAL significantly correlated with grade III and IV of renal biopsy (r=0.67, p=0.009). The sensitivity of UNGAL levels for the diagnosis of LN was 85.7%, with a specificity of 80%.ConclusionUrinary NGAL is a sensitive marker of proliferative nephritis in SLE and disease activity