Comparison urine neutrophil gelatinase - associated lipocalin with standard parameters in monitoring activity Lupus nephritis: Class IV.

Background: Lupus nephritis (LN) is one of the most serious complications in the development of systemic lupus erythematosus, that can adversely affect the course and prognosis of this autoimmune disease. Therefore, monitoring the effect of applied therapy, achieving remission, or monitoring class IV LN activity is still a great challenge for nephrologists. This study aimed to compare the urinary neutrophile gelatinase associated lipocalin (u/NGAL) with traditionally accepted parameters for LNactivity to indicate the importance of its determination in these patients.

Methods: The study group consisted of 40 patients with class IV LN, who were prospectively followed for a period of 4 months within three control visits to 2 months. The first group (20/40) had active disease (Group A), and the second group had diseasein remission (Group B). The parameters we monitored and compared at each visit were standard biochemical parameters and kidney function parameters: C-reactive protein (CRP), blood count (CBC), creatinine, total proteins, albumin, cholesterol, triglycerides, glomerular filtration rate (eGFR). Regarding immune parameters, complement C3 and C4, antinuclear antibodies (ANA), anti-double stranded DNA antibody(anti ds DNA Ab) were monitored. Urine sediment, proteinuria 24h, urine culture, urinary protein/creatinine ratio - Up/Cre, and urinary NGAL (u/NGAL) were monitored in.

Results: Comparing standard parameters of disease activity and u/NGAL between groups, a statistically significant difference was obtained (p < 0.001). Within Group A, comparing the parameters by visits (0 : 2) for anti-ds-DNA Ab a significance of p< 0.05 was obtained, for albumin/s and C3 a significance of p<0.01 was obtained, and proteinuria/24h, Up/Cre, u/NGAL had a significance of p < 0.001. The mean level of u/NGAL was elevated at the initially visit (173.25 ± 172.12 ng/mL), after two months 73.2 ± 48.7 ng/mL, and in the second visit a lower level was recorded (49.60 ± 72.57 ng/mL). The negative correlation of u/NGAL was statistically significant at initial visit with albumin/s (p< 0.01) as well as the positive correlation with proteinuria 24h and Up/Cre (p< 0.001). In visit 2 significant negative correlation of u/NGAL with albumin/s and C3 p< 0.05, and positive correlation with anti-ds-DNA Ab, proteinuria 24h and Up/Cre p < 0.001.

Conclusions: The results of our study indicate that the level of u/N GLA is elevated in patients with active Lupus nephritis class IV, as well as that it correlates with other parameters of disease activity. Serial determination of u/NGAL could be significant in monitoring disease course and treatment.