Abstract
Objectives: To evaluate the impact of systemic lupus erythmatosus (SLE) on urinary levels of podocalyxin and nephrin in urine and to determine its relationship to pathological diagnosis of renal biopsy in lupus nephritis (LN) patients.
Patients & Methods: The study included 50 LN patients diagnosed by renal biopsy according to the International Society of Nephrology (INS) classification. Disease activity was determined using the British Isles Lupus Assessment Group (BILAG). All patients underwent clinical and laboratory evaluation. Urine samples were collected for ELISA estimation of urinary podocalyxin, nephrin, protein and creatinine concentrations and urinary podocalyxin to creatinine (UPxC), urinary nephrin to creatinine (UNC) and urine total protein-to-creatinine (UPC) ratios were calculated.
Results: Urinary levels of nephrin, podocalyxin and protein were significantly higher, while urinary creatinine levels were significantly lower compared to control levels. Consequently, UNC, UPxC and UPC ratios were significantly higher in patients compared to control ratios. Studied patients showed stepwise increase of estimated ratios with increased pathological disease severity grade and ISN grading showed positive significant correlation with the estimated ratios and with BILAG scores, but correlation was most significant with UPxC ratio. ROC curve and regression analyses defined UPxC ratio as the specific significant predictor of pathological grade.
Conclusion: SLE deleteriously affects fine glomerular structure as reflected by increased urinary levels of podocyte-related proteins; podocalyxin and nephrin. Urinary podocalyxin/creatinine ratio significantly predicts the pathological impact of SLE on kidney and could be used as non-invasive marker for such effect and its progression.
|
