Urinary NGAL, cystatin C, β2-microglobulin, and osteopontin significance in hydronephrotic children

Ureteropelvic junction obstruction (UPJO) accounts for 35 % of all congenital hydronephrosis cases. The challenge in managing childhood hydronephrosis is to distinguish obstructive from nonobstructive cases and, thereby, identify patients requiring surgical intervention. This study aimed to examine four urinary proteins as potential biomarkers of obstruction in hydronephrosis. Urine samples from 24 children with UPJO were collected pre-, peri-, and postoperatively, together with urine samples from healthy children. Neutrophil gelatinase-associated lipocalin (NGAL), cystatin C (CyC), beta 2-microglobulin (beta 2-M), and osteopontin (OPN) in the samples were measured simultaneously using multiplex sandwich immunoassay technology. Compared with controls, NGAL and beta 2-M were significantly increased in urine from patients with obstructed kidneys at the time of surgery. This increase was followed by a decrease and stabilization to the same level as that of the controls. Furthermore, age was negatively correlated with preoperative urinary concentrations of CyC, beta 2-M, and OPN. This study confirms increased concentrations of NGAL and beta 2-M in urine from obstructed kidneys and should be tested in larger studies to ascertain their ability to identify obstruction and to determine the importance of age-adjusted reference values.