Urinary NGAL, KIM-1 and L-FABP concentrations in antenatal hydronephrosis

The clinical tests currently in use for obstructive nephropathy (such as renal ultrasonography, differential radionuclide renal scans and urinary creatinine concentration data) are not efficient predictors of the subsequent clinical course. Novel and simple biomarkers are required which, if proven, could be clinically beneficial in determining if a patient is eligible for surgery or reno-protective therapy. More recently, the interest of clinicians has focused on the potential of urinary neutrophil gelatinase-associated lipocalin (uNGAL), urinary kidney injury molecule-1 (uKIM-1) and urinary liver-type fatty acid-binding proteins (uL-FABP) as biomarkers for renal function in children with hydronephrosis (HN).

The purpose of this study was to investigate possible clinical applications of uNGAL, uKIM-1 and uL-FABP as beneficial non-invasive biomarkers to determine whether or not surgical intervention is required in children with HN.

Renal ultrasonography and radionuclide renal scans were used as diagnostic tools to detect HN. Patients were divided into two groups based on the antero-posterior diameter of their renal pelvis and the presence of dysfunction. Group 1 included 26 children with severe HN (with dysfunction), and group 2 consisted of 36 children with mild HN (without dysfunction). Urine samples were collected from 62 children with HN and 20 healthy children.

Hydronephrosis was more common in males than in females, with a male to female ratio of 9:1 in the study sample. The incidence of left kidney involvement (32 patients) was slightly higher than right kidney involvement (28 patients). Compared with controls and group 2, the ratio of uNGAL to creatinine was significantly higher in group 1 (p < 0.05). The biomarker uNGAL/Cr exhibited fairly good diagnostic accuracy, with an area under the curve of 0.68 [95% confidence interval 0.6-0.7] and an optimal cut-off value of 0.16 ng/mg Cr (sensitivity 58%, specificity 75%) (p < 0.05). There was a positive correlation between the uNGAL/Cr ratio and the uKIM-1/Cr ratio (r = 0.582, p < 0.05) and uL-FABP/Cr ratio (r = 0675, p < 0.05) in group 1.

The results clearly demonstrated that children with hydronephrosis and dysfunction had significantly increased uNGAL, and uNGAL/Cr concentrations. However, uKIM-1, uKIM-1/Cr, uL-FABP and uL-FABP/Cr concentrations were not significantly different when compared with controls. These results support the use of uNGAL concentrations as an early marker for renal dysfunction in HN.

The study clearly demonstrated that pediatric patients with hydronephrosis and dysfunction had significantly higher uNGAL to creatinine concentrations as compared with controls.