Evaluation of urinary podocyte level as a noninvasive biomarker in lupus nephritis

Background Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that predominately affects women. It is characterized by a broad spectrum of immunologic and clinical manifestations. Lupus nephritis (LN) is documented as one of the most severe complication of SLE. Aim To investigate the intensity of podocyturia in LN as a noninvasive biomarker and its relation to grade of disease activity. Patients and methods This is a case–control study. It was carried out on 60 patients and 20 control. All participants were randomly selected from those admitted in the internal medicine and rheumatology departments in Al Zahraa University Hospital, Al Hussein University Hospital, and Sayed Galal University Hospital in the period from March 2019 to March 2020. These patients were divided into three groups: group I included 20 healthy controls, group II included 20 patients SLE without nephritis, and group III included 40 patients with LN, which was subdivided into IIIA, which included 20 highly active LN cases and IIIB, which included 20 inactive LN cases. Results In the current work, there was a highly statistically significant difference among the studied groups regarding hemoglobin, white blood cells, creatinine, urea, albumin/creatinine ratio, estimated glomerular filtration rate, anti-DNA, C3, C4, erythrocyte sedimentation rate, C-reactive protein, and antinuclear antibody. Moreover, there was a highly significant difference among the studied groups regarding urinary podocyte marker. There was a statistically significant positive correlation between podocyte marker and creatinine, urea, albumin/creatinine ratio, and anti-DNA in all patients. There was a positive correlation between immunoglobulin (Ig) Cγ and urea and between Ig Cκ and albumin/creatinine and a negative correlation between Ig Cκ and C4 in group III A (active LN). Conclusion SLE deleteriously affects the fine glomerular structures as reflected by augmented urinary levels of podocyte, so we suggested urinary podocyte as a highly sensitive, early, and noninvasive biomarker of LN.