In this prospective study, we measured serum levels of the soluble
urokinase receptor (suPAR) in pediatric patients with
nephrotic syndrome of various etiologies. Mean levels of suPAR were 3316 pg/ml in 99 patients with
steroid-resistant
focal segmental glomerulosclerosis and 3253 pg/ml in 117 patients with biopsy-proven
minimal change disease, which were similar to that of 138 patients with
steroid-sensitive nephrotic syndrome (3150 pg/ml) and 83 healthy controls (3021 pg/ml). Similar proportions of patients in each group had suPAR over 3000 pg/ml. Compared with controls, suPAR levels were significantly higher in patients with
focal segmental glomerulosclerosis (FSGS) and estimated glomerular filtration rate (eGFR) under 30 ml/min per 1.73 m(2) (6365 pg/ml), congenital
nephrotic syndrome (4398 pg/ml), and other proteinuric diseases with or without eGFR under 30 ml/min per 1.73 m(2) (5052 and 3875 pg/ml, respectively; both significant). There were no changes following
therapy and during remission. Levels of suPAR significantly correlated in an inverse manner with eGFR (r=-0.36) and directly with
C-reactive protein (r=0.20). The urinary suPAR-to-
creatinine ratio significantly correlated with
proteinuria (r=0.25) in 151 patients and controls. Using generalized estimating equations approach, serum suPAR significantly correlated with eGFR (coefficient=-13.75), age at sampling (2.72), and
C-reactive protein (39.85). Thus, serum suPAR levels in
nephrotic syndrome are similar to controls, and do not discriminate between FSGS,
minimal change disease, or
steroid-responsive illness.