Table of Contents
ISRN Pediatrics
Volume 2011, Article ID 453271, 3 pages
Case Report

Salt Losing Obstructive Uropathy with Paradoxically Low Urinary Sodium Concentration: Salt Entrapment in an Obstructed Ectopic Ureterocele

Department of Radiology, The University of Chicago Medical Center, 5841 S. Maryland Avenue, MC 2026, Chicago, IL 60637, USA

Received 11 January 2011; Accepted 6 February 2011

Academic Editors: A. Balsamo and R. Bhimma

Copyright © 2011 Steven M. Zangan and David K. Yousefzadeh. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A 6-month-old hyponatremic female with failure to thrive had low urinary sodium concentration. Renal sonography revealed a duplex left collecting system with obstruction of the upper moiety as a blind-ended ectopic ureterocele extending to the bladder base. The echogenicity of the urine within the upper pole system was greater than the bladder contents. We believed that low urinary sodium concentration represented a false negative test and the salt loss by the obstructed left kidney was entrapped in the upper pole collecting system. Prior to ureterocele repair, intraoperative bladder and ureterocele aspirates revealed discordant sodium concentration supporting the sonographic conclusion.