Serum cystatin C, urinary neutrophil gelatinase-associated lipocalin and N-acetyl-beta-D-glucosaminidase in juvenile and adult patients with systemic lupus erythematosus: Correlation with clinical manifestations, disease activity and damage.

Lupus nephritis (LN) is a potentially devastating outcome of systemic lupus erythematosus (SLE). It is important to identify reliable, non-invasive methods to assess the kidneys in patients with SLE. The aim of the study was to measure the level of novel markers of renal involvement in these patients and assess their correlation with disease activity and damage. Sixtyone patients with SLE (33 adults and 28 juvenile) were included in the study. Fifty-two ageand sex-matched healthy individuals served as controls. Full history taking, thorough clinical examination and laboratory investigations were performed and disease activity and damage were assessed for all patients. Renal bio-markers including serum cystatin C, urinary neutrophil gelatinase-associated lipocalin (UNGAL) and N-acetyl-beta-D-glucosaminidase (UNAG) were assessed in patients and controls. There was a significant increase in serum cystatin C, UNGAL and UNAG levels in the adult SLE patients compared with controls (P = 0.000, P = 0.013 and P = 0.018, respectively); serum cystatin C and UNGAL levels were higher in the juvenile patients compared with controls (P = 0.038 and P = 0.000, respectively). Serum cystatin C significantly correlated with the damage index, renal biopsy class and negatively with the serum albumin; UNGAL correlated with albuminuria and the level of nephritis and UNAG negatively correlated with serum albumin level. Our study suggests that serum cystatin C, UNGAL and UNAG are important markers of LN and both cystatin C and UNAG would help in predicting the renal biopsy class.