# Evaluation of spot urine CA 19 − 9/creatinine ratio in diagnosis and management of hydronephrosis in children: a prospective study

## TL;DR

The study explores if a urine test for CA19-9 can help diagnose kidney blockages in children.

## Contribution

The study introduces the CA19-9/creatinine ratio as a potential non-invasive biomarker for hydronephrosis in children.

## Key findings

- CA19-9/creatinine levels were significantly higher in children with hydronephrosis compared to healthy controls.
- No significant difference was found between obstructive and non-obstructive hydronephrosis groups.
- Post-surgery, CA19-9/creatinine levels decreased in children with UPJO.

## Abstract

To demonstrate that the CA19-9/creatinine level could be a potential biomarker in children with obstruction by including ureteropelvic junction obstruction (UPJO) patients and comparing them not only with healthy controls but also with children with non-obstructive hydronephrosis (HN).

Children with HN and healthy controls with no HN were prospectively enrolled into study from March 2021 to December 2022. The children with HN were divided into two separate groups. Group 1 consisted of children with UPJO, while Group 2 included children with lower urinary tract dysfunction (LUTD). Data collected from study and control groups included age, gender, spot urine CA 19 − 9/Cr ratio at the initial visit and at the 6-month follow-up, the Society of Fetal Urology (SFU) grade, antero-posterior (AP) diameter, renal function and diuretic response on mercaptoacetyltriglycine (MAG-3) dynamic renal scintigraphy and surgical or conservative management selection. Spot urine CA 19 − 9 levels were measured using the ELISA method.

Out of 283 children, Group 1 consisted of 40 children (11 girls, 29 boys; median age: 7 years), Group 2 comprised 18 children (10 girls, 8 boys; median age:8 years) and 225 healthy controls (83 girls, 142 boys; median age: 8 years). The spot urine CA 19 − 9/Cr ratio was significantly higher in the Group 1 and 2 compared to controls (respectively 86.7, 64.5, 47.1 U/mg Cr, p = 0.0001). When the two patient groups with HN were compared with each other, no statistically significant difference was observed in the urinary CA19-9/creatinine levels (p = 0.358). No correlation was found between CA 19 − 9/Cr ratio and HN severity and/or dynamic renal scintigraphy findings. Surgical management of unilateral UPJO revealed a decrease in CA 19 − 9/Cr in the study group.

This study suggests that the spot urine CA 19 − 9/creatinine ratio may serve as a promising, non-invasive biomarker for distinguishing children with unilateral UPJO and non-obstructive HN from healthy controls. Although elevated levels in patients and postoperative decline were observed, its inability to predict HN severity or the necessity for surgical intervention limits its clinical utility.

Keywords: CA19-9, biomarker, ureteropelvic junction obstruction, hydronephrosis, lower urinary tract dysfunction