Comparison of Urinary Biomarkers in Diagnosis of Ureteropelvic Junction Obstruction and Differentiation from Nonobstructive Dilatation.

Background And Aims: Differentiation of nonobstructive dilatation (NOD) from ureteropelvic junction obstruction (UPJO) is a challenge in children with antenatally detected hydronephrosis. The aim of this study is to compare the utility of urinary biomarkers: carbohydrate antigen (CA 19-9), neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule (KIM) in diagnosing UPJO.

Methods: A prospective study was conducted after obtaining ethical clearance between 2021 and 2022. Group 1 - control group ( = 30): children with normal antenatal ultrasound with no urinary symptoms. Group 2 - study group ( = 48): children with unilateral hydronephrosis: Group 2a - NOD ( = 24): children stable on ultrasound and diuretic renogram and Group 2b - UPJO ( = 24): children who worsened to Grade 4 hydronephrosis on ultrasound/worsening of differential renal function (10% drop) on renogram who underwent pyeloplasty. Urinary biomarkers NGAL, KIM-1, and CA 19-9 were measured using the enzyme-linked immune absorbent assay method.

Results: The urine CA 19-9 level was 128.05 ± 4.08 U/mL in the UPJO group, and this was significantly higher ( = 0.001) than NOD, 70.29 ± 4.41, and controls, 1.91 ± 1.57. The urine NGAL level was 21.41 ± 4.44 pg/mL in UPJO, and this was significantly higher than controls, 2.669 ± 0.513, but not NOD, 24.55 ± 2.67. The urine KIM level was 817 ± 15.84 pg/mL in the UPJO group, and this was significantly higher than controls, 285 ± 8.10, but not NOD, 768.23 ± 15.12. Receiver operating characteristic analysis of CA 19-9 revealed a urine biomarker cutoff of 95 U/mL for diagnosing UPJO (sensitivity 95%; specificity 96%; and area under the curve 0.99).

Conclusions: CA 19-9 is a superior marker compared to NGAL and KIM in differentiating UPJO from NOD. Further studies with larger numbers are warranted.