Evaluation of serum soluble urokinase plasminogen activator receptor as a marker for steroid-responsiveness in children with primary nephrotic syndrome

Abstract

Nephrotic syndrome (NS) is the most common primary glomerular disease among children. It runs a relapsing course involving prolonged periods of treatment with corticosteroids and other immunosuppressive medications. Soluble urokinase plasminogen activator receptor (suPAR) has been regarded as an inflammatory as well as a permeability factor. The aim of our study was to evaluate serum suPAR levels in children with NS and its relation to steroid responsiveness. Our study was carried out on 75 children who were already diagnosed as having NS; they were classified into three groups (steroid sensitive, steroid dependent, and steroid resistant). Furthermore, 40 apparently healthy children, age and sex matched with the NS patients, were enrolled as controls. All children had undergone assessment of serum suPAR, renal function tests (urea and creatinine), serum albumin, C-reactive protein, and 24-h protein in urine. The study found that suPAR level was significantly different between the studied groups (P <0.05), being highest in steroid-resistant NS (66.52 ± 9.7 ng/mL), followed by steroid dependent (56.82 ± 11.09 ng/mL), and steroid-sensitive patients (26.22 ± 3.86 ng/mL), and lowest in the control group (20.29 ± 0.69 ng/mL). When receiver operating characteristics curves were plotted, suPAR had high sensitivities and specificities in predicting steroid responsiveness, [area under the curve (AUC) = 0.99, 95% confidence interval (CI) = 0.911–1.000, P <0.001], steroid dependence (AUC = 1.00, 95% CI = 0.929–1.000, P <0.001), and predicting steroid resistance. Our study indicates that suPAR is significantly higher in children with primary NS and varies according to their response to steroid therapy. It may act as a marker for steroid responsiveness in these children.