Urinary carbohydrate antigen 19-9/creatinine ratio: A non-invasive marker for follow-up of unilateral ureteropelvic junction obstruction in children

Abstract

INTRODUCTION: Ureteropelvic junction obstruction (UPJO) is the most common cause of hydronephrosis in children. One major challenge in the management of UPJO is to select the patients that must be subjected to early obstruction relief. Currently, there is no gold standard for this assessment. Therefore, the aim of the present study was to evaluate the urinary levels of carbohydrate antigen (CA) 19-9 and normalized CA 19-9 (Ca 19-9/Cr ratio) in UPJO patients before and after surgery and compare them with a control group to assess their potential clinical application as an assisting tool in diagnosis of UPJO patients. MATERIAL AND METHODS: From Jan 2013 to Jun 2016, 30 children with history of inguinal hernia, circumcision, hydrocele, and undescended testis as the control group (group 1) and 30 children with unilateral congenital UPJO (group 2) were enrolled in the study. Random CA 19-9 and random creatinine were measured in the voided urine samples of control group and proven congenital UPJO group preoperatively (group 2A) and at 6 months after dismembered pyeloplasty (group 2B). In addition, the random urinary CA 19-9/CR ratio was evaluated as a marker to normalized urinary CA 19-9. DISCUSSION: The urinary CA 19-9/Cr ratio was significantly greater in the UPJO group than in the control group. The urinary CA 19-9 also was more in group 2A than in group 1; however, it was not statistically significant. The urinary CA 19-9/Cr ratio and renal pelvis anteroposterior diameter decreased significantly in the group 2B 6 month after complete relief of obstruction in comparison with group 2A preoperatively. Urinary CA 19-9 also decreased in 2B group though it was not significant. CONCLUSION: Urinary CA 19-9/Cr ratio is suggested as a non-invasive marker that can assist in diagnosis and long-term follow-up of UPJO patients. This ratio is superior to urinary CA 19-9 as it is more strongly correlated with UPJ obstruction.