Saudi Journal of Kidney Diseases and Transplantation

LETTER TO THE EDITOR
Year
: 2013  |  Volume : 24  |  Issue : 5  |  Page : 1022--1023

Comparison of urinary citrate excretion between patients with nephrolithiasis and healthy volunteers


Peyman Roomizadeh1, Bahareh Mehdikhani2,  
1 Isfahan Kidney Diseases Research Center; Medical Students Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
2 Medical School, Tehran University of Medical Sciences, Tehran, Iran

Correspondence Address:
Peyman Roomizadeh
Isfahan Kidney Diseases Research Center; Medical Students Research Center, Isfahan University of Medical Sciences, Isfahan
Iran




How to cite this article:
Roomizadeh P, Mehdikhani B. Comparison of urinary citrate excretion between patients with nephrolithiasis and healthy volunteers.Saudi J Kidney Dis Transpl 2013;24:1022-1023


How to cite this URL:
Roomizadeh P, Mehdikhani B. Comparison of urinary citrate excretion between patients with nephrolithiasis and healthy volunteers. Saudi J Kidney Dis Transpl [serial online] 2013 [cited 2021 Mar 7 ];24:1022-1023
Available from: https://www.sjkdt.org/text.asp?2013/24/5/1022/118083


Full Text

To the Editor,

We read with great interest the recent article by Goodarzi et al comparing low urinary citrate excretion between patients with kidney stones and healthy individuals. [1] Hypocitraturia has long been established as a major risk factor for calcium stone formation. The overall prevalence of hypocitraturia among kidney stone formers varies from 20% to 60% in different studies around the world. [2] Despite such observational reports, in some other studies including one major cohort from the United States, the frequency of hypocitraturia was not significantly different between stone formers and controls. [3] In the Goodarzi et al study, low urinary citrate excretion in nephrolithiasis patients was significantly higher than that in the control group. [1] However, before such a conclusion can be made, two methodological issues should be considered. We wonder whether the authors could explain them.

First, in this study, calcium stones (calcium oxalate and calcium phosphate) were present in 82% of the patients. [1] There was no description regarding the types of kidney stones in the remaining 18% of the patients. Because hypo-citraturia is not an underlying metabolic cause for non-calcareous stones (e.g., struvite, uric acid or cysteine stones), it would have been better if the authors have included only calcium stone formers as the case group.

Second, the case group in this study consisted of only recurrent stone formers ("having at least two times history of nephrolithiasis"). [1] It is well known that the prevalence of hypocitraturia among recurrent stone formers is higher than that in the first time stone formers. [4],[5] Given this, a case group consisting of only recurrent stone formers may have a lower mean level of urinary citrate than a case group consisting of both recurrent and first time stone formers. In this regard, it would have been better if the authors had also included the first time stone formers in their study for better comparison of urinary citrate excretion between nephrolithiasis patients and healthy individuals.

References

1Goodarzi MT, Forouzanfar F, Moaddab AH, Karimian M, Sabzevar NK. Comparison of 24-hour urinary citrate excretion in stone formers and healthy volunteers. Saudi J Kidney Dis Transpl 2012;23:1227-31.
2Zuckerman JM, Assimos DG. Hypocitraturia: Pathophysiology and medical management. Rev Urol 2009;11:134-44.
3Curhan GC, Willett WC, Speizer FE, Stampfer MJ. Twenty-four-hour urine chemistries and the risk of kidney stones among women and men. Kidney Int 2001;59:2290-8.
4Cupisti A, Morelli E, Lupetti S, Meola M, Barsotti G. Low urine citrate excretion as main risk factor for recurrent calcium oxalate nephrolithiasis in males. Nephron 1992;61:73-6.
5Yagisawa T, Chandhoke PS, Fan J. Metabolic risk factors in patients with first-time and recurrent stone formations as determined by comprehensive metabolic evaluation. Urology 1998;52:750-5.