CC BY 4.0 · Journal of Child Science 2019; 09(01): e1-e6
DOI: 10.1055/s-0039-1677818
Original Article
Georg Thieme Verlag KG Stuttgart · New York

Does the Urinary Calcium/Citrate Ratio Add to the Diagnostic Workup of Children at Risk of Kidney Stones? A Cross-Sectional Study

Misan Lee
1   Department of Paediatrics, Division of Paediatric Nephrology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
,
Carmen Inés Rodriguez Cuellar
1   Department of Paediatrics, Division of Paediatric Nephrology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
2   Departamento de Nefrología Pediátrica, Instituto Nacional de Pediatría, Mexico City, Mexico
3   Universidad Nacional Autónoma de México, Mexico City, Mexico
,
Ravneet Nagra
1   Department of Paediatrics, Division of Paediatric Nephrology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
,
Zhan Tao Peter Wang
5   Department of Surgery, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
,
Vipin Bhayana
6   Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
,
Guido Filler
1   Department of Paediatrics, Division of Paediatric Nephrology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
4   Lilibeth Caberto Kidney Clinical Research Unit, London Health Sciences Centre, London Ontario, Canada
6   Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
7   Department of Medicine, Division of Nephrology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
› Author Affiliations
Further Information

Publication History

24 August 2018

03 January 2019

Publication Date:
07 February 2019 (online)

Abstract

The purpose of the study was to evaluate urinary citrate/creatinine (UCi/UCr) and urinary calcium/citrate (UCa/UCi) ratios for distinguishing stone formers (SF) from non-stone formers (NSF) in an at-risk population. This was a retrospective study that included all pediatric patients who underwent urinary citrate testing from April 2017 to March 2018. The urinary levels of citrate, calcium, sodium, potassium, creatinine, oxalate, urate, pH, and specific gravity (SG) were measured in our clinical laboratory. Diagnosis of kidney stones was obtained through chart review.

A total of 97 patients were included (46 NSF and 51 SF). The UCi/UCr ratio was not significantly different between NSF and SF. Median UCa/UCr ratio was higher in SF (0.67) compared with NSF (0.21, p < 0.0001). The median ratio of UCa/UCi was also higher in SF (1.30) than in NSF (0.65, p = 0.001). Oxalate, urate, pH, SG, and urinary sodium/potassium ratio did not differentiate between the SF and NSF. Positive correlation was seen between UCa/UCr and urinary sodium/creatinine UNa/UCr (p < 0.0001), as well as between UCa/UCr and UCi/UCr (p < 0.0001).

The study has demonstrated significantly higher UCa/UCi and UCa/UCr in SF compared with NSF, while the use of urinary oxalate, urate, pH, and SG did not differentiate between SF from NSF. We also confirmed a positive correlation between UNa/UCr and UCa/UCr. While the utility of UCa/UCr is well established, our data suggest that UCa/UCi rather than UCi/UCr may be more predictive in the clinical setting when evaluating for nephrolithiasis.

Authors' Contributions

GF and ML articulated the conceptual framework for this study and obtained ethics approval. VB retrieved the urinary citrate concentrations from the laboratory information system and linked all available data. ML pulled all the charts and performed the data entry. GF developed the analytical approach and GF, ML, CIRC, and RN analyzed the data. GF and CIRC drafted the manuscript. RN, PW, and VB contributed to the interpretation of data, added intellectual content during manuscript preparation, and provided valuable feedback on various aspects of the manuscript. All authors read and approved the final manuscript.


 
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