Ch'ng LS. et al., 2022: Does alkalinised urine reduce the rate of encrustation in patients with ureteric stents? A randomised controlled study.

Wednesday, 10 August 2022

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Ch'ng LS, Toh CC, Sathiyananthan JR, Malek R.
Department of Urology, Hospital Selayang, Gombak, Selangor, Malaysia.
Department of Urology, Hospital Selayang, Gombak, Selangor, Malaysia.

Abstract

Purpose: Stent encrustation is not uncommonly encountered with a high number of ureteric stents. The exact pathophysiology is not well understood. Therefore, we investigated the relationship between the use of sodium citrate and likelihood of stent encrustation.

Methods: This prospective, randomised, intervention study was conducted between October 2018 and October 2019 in a tertiary hospital. Overall, 115 patients with ureteral stents that were inserted after lithotripsy surgeries were recruited. The study subjects were randomised into two groups: one group was administered sodium citrate (Utix sachets) three times per day until stent removal (intervention group), and the second group was not administered Utix sachets (control group). Stents were removed after 1 month and inspected under macroscopic visualisation from the proximal to distal end for any crystallisation; a second inspection was done with a 60 × magnification lens. Any crystallisation observed was considered to be encrustation.

Results: Patients who had Utix sachets post-insertion of a ureteric stent constituted 50.4% of the study cohort. The rate of encrustation in the control group was 52.6%. In the intervention group, the rate of encrustation was 46.6%. The difference was not statistically significant with the chi-squared test (p value, 0.514).

Conclusion: Alkaline citrate medications had no significant effect on stent encrustation rate. More studies are needed to elucidate different agents and their roles in reducing stent encrustation as it incurs high morbidity.
Int Urol Nephrol. 2022 Mar;54(3):509-515. doi: 10.1007/s11255-022-03105-8. Epub 2022 Jan 26. PMID: 35080681 Clinical Trial.

Comments 1

Hans-Göran Tiselius on Wednesday, 10 August 2022 10:30

The title of this article raises some interest because stents not uncommonly are used in association with SWL. It is of note, however, that none of the patients included in this RCT had been treated with SWL. Nevertheless, the encrustation problem deserves attention.

It is not mentioned what kind of salts that usually comprise encrustations in the authors’ region, and no analysis of the composition of the identified encrustations apparently was carried out. From a theoretical point of view crystallization of CaOx is reduced in urine with high citrate and high pH. Experimental studies have shown inhibitory effects of citrate also on MAPCarbAp crystallization [1], but it is doubtful if that effect is sufficient to overcome the crystallisation driving force in a long-term perspective.

Alkaline urine is powerful for counteracting uric acid crystal formation. On the other hand, CaP precipitation will be increase in urine with high pH.
So, what can be expected when urine pH and citrate are increased?
One problem is that that the encrustations can be composed of both CaOx and MAPCarbAp and it has been shown that whereas CaOx might precipitate on the renal loop, infection stone material may be the component on the bladder loop [2].

In the current report it was not possible to demonstrate any significant difference between the two methods aiming at reduced crystal formation. Unfortunately, the two groups were scientifically not clean, and the treatment group received 1500 mL extra fluid during the day (Together with the Utix sachets).

It had been desirable with a study easier to interpret. The pH-levels before and at the end of the stent treatment period are not shown. Neither is the result of urine cultures. It also is difficult to know what the authors mean by “after the operation”.

It is worth mentioning that in another recent report stent crystallization was counteracted by acidification with methionine + phytate.

The conclusion is that the problem of stent crystallization needs to be studied in more detail. Otherwise it will be difficult to establish an effective treatment regimen.

References

1.Y H Wang , L Grenabo, H Hedelin, S Pettersson The effects of sodium citrate and oral potassium citrate on urease-induced crystallization. Br J Urol 1994 ;74(4):409-415.

2.Sighinolfi MC, Sighinolfi GP, Galli E, Micali S, Ferrari N, Mofferdin A, Bianchi G. Chemical and Mineralogical Analysis of Ureteral Stent Encrustation and Associated Risk Factors. Urology. 2015 ;86(4):703-706.

3.Torrecilla C, Fernández-Concha J, Cansino JR, Mainez JA, Amón JH, Costas S, Angerri O, Emiliani E, Arrabal Martín MA, Arrabal Polo MA, García A, Reina MC, Sánchez JF, Budía A, Pérez-Fentes D, Grases F, Costa-Bauzá A, Cuñé J. Reduction of ureteral stent encrustation by modulating the urine pH and inhibiting the crystal film with a new oral composition: a multicenter, placebo controlled, double blind, randomized clinical trial. BMC Urol. 2020;20(1):65.

Hans-Göran Tiselius

It is not mentioned what kind of salts that usually comprise encrustations in the authors’ region, and no analysis of the composition of the identified encrustations apparently was carried out. From a theoretical point of view crystallization of CaOx is reduced in urine with high citrate and high pH. Experimental studies have shown inhibitory effects of citrate also on MAPCarbAp crystallization [1], but it is doubtful if that effect is sufficient to overcome the crystallisation driving force in a long-term perspective.

Alkaline urine is powerful for counteracting uric acid crystal formation. On the other hand, CaP precipitation will be increase in urine with high pH.
So, what can be expected when urine pH and citrate are increased? 
One problem is that that the encrustations can be composed of both CaOx and MAPCarbAp and it has been shown that whereas CaOx might precipitate on the renal loop, infection stone material may be the component on the bladder loop [2].

In the current report it was not possible to demonstrate any significant difference between the two methods aiming at reduced crystal formation. Unfortunately, the two groups were scientifically not clean, and the treatment group received 1500 mL extra fluid during the day (Together with the Utix sachets).

It had been desirable with a study easier to interpret. The pH-levels before and at the end of the stent treatment period are not shown. Neither is the result of urine cultures. It also is difficult to know what the authors mean by “after the operation”.

It is worth mentioning that in another recent report stent crystallization was counteracted by acidification with methionine + phytate.

The conclusion is that the problem of stent crystallization needs to be studied in more detail. Otherwise it will be difficult  to establish an effective treatment regimen.

References

1.Y H Wang , L Grenabo, H Hedelin, S Pettersson The effects of sodium citrate and oral potassium citrate on urease-induced crystallization. Br J Urol 1994 ;74(4):409-415.

2.Sighinolfi MC, Sighinolfi GP, Galli E, Micali S, Ferrari N, Mofferdin A, Bianchi G. Chemical and Mineralogical Analysis of Ureteral Stent Encrustation and Associated Risk Factors. Urology. 2015 ;86(4):703-706.

3.Torrecilla C, Fernández-Concha J, Cansino JR, Mainez JA, Amón JH, Costas S, Angerri O, Emiliani E, Arrabal Martín MA, Arrabal Polo MA, García A, Reina MC, Sánchez JF, Budía A, Pérez-Fentes D, Grases F, Costa-Bauzá A, Cuñé J. Reduction of ureteral stent encrustation by modulating the urine pH and inhibiting the crystal film with a new oral composition: a multicenter, placebo controlled, double blind, randomized clinical trial. BMC Urol. 2020;20(1):65.

Hans-Göran Tiselius

The title of this article raises some interest because stents not uncommonly are used in association with SWL. It is of note, however, that none of the patients included in this RCT had been treated with SWL. Nevertheless, the encrustation problem deserves attention. It is not mentioned what kind of salts that usually comprise encrustations in the authors’ region, and no analysis of the composition of the identified encrustations apparently was carried out. From a theoretical point of view crystallization of CaOx is reduced in urine with high citrate and high pH. Experimental studies have shown inhibitory effects of citrate also on MAPCarbAp crystallization [1], but it is doubtful if that effect is sufficient to overcome the crystallisation driving force in a long-term perspective. Alkaline urine is powerful for counteracting uric acid crystal formation. On the other hand, CaP precipitation will be increase in urine with high pH. So, what can be expected when urine pH and citrate are increased? One problem is that that the encrustations can be composed of both CaOx and MAPCarbAp and it has been shown that whereas CaOx might precipitate on the renal loop, infection stone material may be the component on the bladder loop [2]. In the current report it was not possible to demonstrate any significant difference between the two methods aiming at reduced crystal formation. Unfortunately, the two groups were scientifically not clean, and the treatment group received 1500 mL extra fluid during the day (Together with the Utix sachets). It had been desirable with a study easier to interpret. The pH-levels before and at the end of the stent treatment period are not shown. Neither is the result of urine cultures. It also is difficult to know what the authors mean by “after the operation”. It is worth mentioning that in another recent report stent crystallization was counteracted by acidification with methionine + phytate. The conclusion is that the problem of stent crystallization needs to be studied in more detail. Otherwise it will be difficult to establish an effective treatment regimen. References 1.Y H Wang , L Grenabo, H Hedelin, S Pettersson The effects of sodium citrate and oral potassium citrate on urease-induced crystallization. Br J Urol 1994 ;74(4):409-415. 2.Sighinolfi MC, Sighinolfi GP, Galli E, Micali S, Ferrari N, Mofferdin A, Bianchi G. Chemical and Mineralogical Analysis of Ureteral Stent Encrustation and Associated Risk Factors. Urology. 2015 ;86(4):703-706. 3.Torrecilla C, Fernández-Concha J, Cansino JR, Mainez JA, Amón JH, Costas S, Angerri O, Emiliani E, Arrabal Martín MA, Arrabal Polo MA, García A, Reina MC, Sánchez JF, Budía A, Pérez-Fentes D, Grases F, Costa-Bauzá A, Cuñé J. Reduction of ureteral stent encrustation by modulating the urine pH and inhibiting the crystal film with a new oral composition: a multicenter, placebo controlled, double blind, randomized clinical trial. BMC Urol. 2020;20(1):65. Hans-Göran Tiselius

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