This study evaluates the effectivity in urinary pH Control and the prevention of calcification in Double J stent using a device combined with the intake of dietary supplements. Every patient will receive hygienic-dietary indications.

Patients will also take one out of the three dietary supplements regarded within the study (pH Up, pH Down and Cysteine) to control the adequate pH level, always following medical indications.

Several studies have shown the importance of urinary pH Control (pHv) to determine the frequency of stent incrustation, this measure being a variable to be taken into account in the management of catheterized patients. However, the level of pHv is influenced by multiple factors, so its routine control is difficult to interpret. The nucleation pH (pHn) was described on 1999: the pH where the incrustation starts to form. In his study he observed that the pH of the patients who developed a stent blockage and the pH of those who were not very similar (7.46 and 7.38 respectively), but observed that the pHv of the patients who did not have incrustations was much lower and therefore had a much wider safety margin.

As already mentioned, pHv is influenced by different factors, but it is especially sensitive to diet. For this reason, hygienic and dietetic interventions (exercise, diet, fluid intake, etc.) are one of the preventive measures of incrustation of the stent of great utility, although its effectiveness is subject to patient adherence.

Lit-control®pH Down is a dietary supplement with an acidifying effect on urine, which helps in the prevention of complications arising from the alkalinization of urine. It contains L-methionine, phytin (calcium-magnesium phytate salt), zinc and vitamin A. The two active components in pHv acidification are L-methionine and phytin,while zinc and vitamin A increase the action of phytin. Specifically, zinc favors the affinity of its affinity for calcium phosphate and vitamin A prevents its degradation by alkaline phosphatase.

L-methionine is an essential amino acid that plays an important role in metabolic processes. It is normally acquired through food and absorbed in the small intestine to be metabolized in the liver via cysteine to sulphate and protons. Consequently, its administration produces a significant reduction of urinary pH.

According to the European Association of Urology (UAE), urinary acidification with L-methionine up to pH 5.8 - 6.2 is recommended as a therapeutic measure for calculations of struvite, calcium phosphate and ammonium urate at doses of 600- 1500 mg / day. This recommendation is based on the results observed in 1996, where an acidification of the pH of the urine of the patients was observed from 7.5 to 5.5 after the administration of 1500-3000 mg / day (3-6 capsules) of 500mg / day. Also in the study of Hesse 1999 a significant reduction in urinary pH was observed up to pH = 6.0 after the administration of a single dose of 1500 mg of L-methionine, maintaining this effect for 24h. In addition, a significant reduction was observed versus the control group in terms of the relative supersaturation for struvite and brushite in the urine of 24h. In another more recent study, the authors studied the circadian course of urinary pH after the administration of 1500 mg of L-methionine. They observed a strong decrease in urinary pH up to 2h after the administration of the amino acid that remained at significantly low levels for 8h, resulting in a pH level for 24h between 5.98 and 6.32. Therefore, in order to guarantee therapeutic doses of L-Methionine (1500mg / day), the Lit-control®pH Down regimen to follow would be equivalent to 3 capsules per day (500 mg / capsule).

On the other hand, the device Lit-control® pH Meter is a medical device that allows patients to self-monitor their pHv daily in their own home, allowing a thorough control of the pH and the level of risk of incrustation. The device has been validated for use in lithiasic patients, with applicability in the treatment of other urological pathologies related to the acid-base balance of urine, calcifications of urinary stents, cystitis, urinary tract infections, painful bladder syndrome and bladder hyperactive

The objective of this study is to evaluate the effectiveness of the food supplement Lit-control®pH Down in the prevention of double J stent incrustation and in the control of urinary pH together with the use of the device Lit-control® pH meter

Inclusion Criteria:

• Age ≥18 years old
• Patients which have been recently implanted a Double J stent (less than a week implant) or who have planned their implant and have been recommended with pH control to avoid incrustation/calcification.
• Patients who accept their participation in the study and give their informed consent

Exclusion Criteria:

• Patients with base pathologies wich , based on clinical criteria, aren´t sensitive about the study dietary supplement indications.
• Patients which have programmed the stent extraction 3 weeks before base visit.
• Uric and cystinuric patients which requires pH control different from the established study protocol .