Medical management of urinary stone disease

The effectiveness of citrates and pyridoxine in the treatment of kidney stones

The prevalence of nephrolithiasis is increasing across all demographic groups. Apart from the morbidity associated with an acute occurrence, preventative treatment is essential for stone disease, which can become a long-term problem. Simple interventions like fluid intake optimization and dietary modification are effective for most stone types. However, patients with specific metabolic abnormalities may require pharmaceutical therapy if lifestyle changes are insufficient to reduce the risk of stone recurrence. The treatment of citrates and/or pyridoxines may help eliminate or prevent recurrences of kidney stones, especially when they are composed of uric acid, calcium oxalate, calcium phosphate, or the latter two together. In cases of struvite stones, which often necessitate a surgical approach, acetohydroxamic acid emerges as a valuable second-line treatment option. Thiol-binding agents may be needed for cystinuria, as well as lifestyle modifications. Successful treatment reduces stone recurrence and the need to remove stones surgically.

Proton pump inhibitors use and risk of incident nephrolithiasis

Proton pump inhibitors (PPIs) are widely prescribed medications that have effects on both enteric and urinary solute handling with an unknown effect on risk of nephrolithiasis. Our objectives were to examine the association between PPI exposure and incident nephrolithiasis and to determine its effect on 24H urine chemistry. We performed a single-center retrospective study on patients diagnosed with gastroesophageal reflux disease (GERD) without a history of kidney stones. Exposure to PPIs was abstracted, and then subsequent kidney stone diagnoses were identified. Multivariable Cox models with time-varying covariates were used to estimate the hazard of PPI use on incident nephrolithiasis. We used multivariable linear regression to analyze a subset of patients who went through 24-h urine analysis. We identified n = 55,765 PPI-naïve GERD patients without prior kidney stone diagnoses of whom 40,866 (73.2%) were exposed to PPI over a median of 3 year follow up. On multivariable analysis, PPI use was associated with higher risk of incident kidney stone diagnoses (HR 1.19, 95% CI 1.06-1.34). Among 593 patients with GERD with 24-H urine data, the PPI-exposed group (n = 307) had significantly lower mean urinary citrate (mean 3.0 vs 3.4 mmol, p = 0.029) and urinary magnesium (mean 3.6 vs 4.3 mmol, p < 0.001) on multivariable analyses. Exposure to PPIs is associated with an increased risk of kidney stones among patients with GERD. Hypomagnesemia and hypocitraturia associated with PPI exposure may contribute to kidney stone risk.

Comprehensive review on naringenin and naringin polyphenols as a potent anticancer agent

Though the incidence of several cancers in Western societies is regulated wisely, some cancers such as breast, lung, and colorectal cancer are currently rising in many low- and middle-income countries due to increased risk factors triggered by societal and development problems. Surgery, chemotherapy, hormone, radiation, and targeted therapies are examples of traditional cancer treatment approaches. However, multiple short- and long-term adverse effects may also significantly affect patient prognosis depending on treatment-associated clinical factors. More and more research has been carried out to find new therapeutic agents in natural products, among which the bioactive compounds derived from plants have been increasingly studied. Naringin and naringenin are abundantly found in citrus fruits, such as oranges and grapefruits. A variety of cell signaling pathways mediates their anti-carcinogenic properties. Naringin and naringenin were also documented to overcome multidrug resistance, one of the major challenges to clinical practice due to multiple defense mechanisms in cancer. The effective parameters underlying the anticancer effects of naringenin and naringin include GSK3β inactivation, suppression of the gene and protein activation of NF-kB and COX-2, JAK2/STAT3 downregulation, downregulation of intracellular adhesion molecules-1, upregulation of Notch1 and tyrocite-specific genes, and activation of p38/MAPK and caspase-3. Thus, this review outlines the potential of naringin and naringenin in managing different types of cancers.

Effects of high-sodium diet on lithogenesis in a rat experimental model of calcium oxalate stones

Background

This study aimed to investigate the effects of a high- and low-sodium diets on lithogenesis in a rat experimental model of calcium oxalate stones.

Methods

Twenty male Wistar rats were randomly divided into four groups; group A: 4% NaCl+1% ethylene glycol (EG); group B: 8% NaCl+1% EG; group C: 8% NaCl+normal drinking-water; group D: 1% EG +normal diet. All rats were sacrificed 4 weeks later, and blood samples were collected from the heart. The kidneys were collected for Von Kossa staining to evaluate the formation of calcium-containing crystals. The last 24-h urine samples were also gathered for metabolic analysis.

Results

Von Kossa staining demonstrated that the rats in both group A and group B had significantly more renal calcium crystals than those in group D. However, 24-h urinary volume increased significantly (142.26±20.91 mL) in group B compared with group A (100.52±28.23 mL), group C (107.36±14.24 mL), group D (40.79±8.71 mL) (P=0.004, 0.012, and 0.000 respectively). Level of urine sodium (Na), potassium (K), chlorine (Cl), and calcium (Ca), urea nitrogen were significantly higher in group B compared with group D. The urine phosphorus, oxalate, and creatinine levels; urine specific gravity; and urine PH were similar between group B and group D. The level of serum sodium was higher in group B (151.26±4.06 mmol/L) compared with group D (145.56±1.12 mmol/L) (P=0.002).

Conclusions

A high sodium intake might increase the risk of lithogenesis in susceptible individuals (given by EG) or in individuals with water restriction.

Lime (Citrus aurantifolia (Christm.) Swingle) Essential Oils: Volatile Compounds, Antioxidant Capacity, and Hypolipidemic Effect

Lime peels are mainly obtained from the byproducts of the juice manufacturing industry, which we obtained and used to extract essential oil (2.3%) in order to examine the antioxidant and hypolipidaemic effects. We identified 60 volatile compounds of lime essential oil (LEO) with GC/MS, of which the predominant constituents were limonene, γ-terpinene, and β-pinene. Lime essential oil was measured according to the DPPH assay and ABTS assay, with IC₅₀ values of 2.36 mg/mL and 0.26 mg/mL, respectively. This study also explored the protective effects of LEO against lipid-induced hyperlipidemia in a rat model. Two groups of rats received oral LEO in doses of 0.74 g/100 g and 2.23 g/100 g with their diets. Eight weeks later, we found that the administration of LEO improved the serum total cholesterol, triglyceride, low-density lipoprotein cholesterol, alanine aminotransferase, and aspartate transaminase levels in the hyperlipidemic rats (p < 0.05). Simultaneously, the LEO improved the health of the rats in terms of obesity, atherogenic index, and fatty liver.

Low Sodium Diet Decreases Stone Formation in Genetic Hypercalciuric Stone-Forming Rats

BACKGROUND

Urine (u) calcium (Ca) excretion is directly dependent on dietary sodium (Na) intake leading to the recommendation for Na restriction in hypercalciuric kidney stone formers. However, there is no direct evidence that limiting Na intake will reduce recurrent stone formation.

MATERIALS AND METHODS

We used genetic hypercalciuric stone-forming (GHS) rats, which universally form Ca phosphate (P) kidney stones, fed either a low Na (LNa, 0.05%) or normal Na (NNa, 0.4%) Na diet (D) for 18 weeks. Urine was collected at 6-week intervals. Radiographic analysis for stone formation and bone analyses were done at the conclusion of the study.

RESULTS

Mean uCa was lower with LNaD than NNaD as was uP and LNaD decreased mean uNa and uChloride. There were no differences in urine supersaturation (SS) with respect to calcium phosphate (CaP) or Ca oxalate (CaOx). However, stone formation was markedly decreased with LNaD by radiographic analysis. The LNaD group had significantly lower femoral anterior-posterior diameter and volumetric bone mineral density (vBMD), but no change in vertebral trabecular vBMD. There were no differences in the bone formation rate or osteoclastic bone resorption between groups. The LNaD group had significantly lower femoral stiffness; however, the ultimate load and energy to fail was not different.

CONCLUSION

Thus, a low Na diet reduced uCa and stone formation in GHS rats, even though SS with respect to CaP and CaOx was unchanged and effects on bone were modest. These data, if confirmed in humans, support dietary Na restriction to prevent recurrent Ca nephrolithiasis.

Coconut Water: An Unexpected Source of Urinary Citrate

Purpose

Coconut water has long been touted for its medicinal qualities including natural hydration. We sought to determine whether its consumption would induce changes to urinary lithogenic factors beyond changes in urine volume.

Materials and Methods

After Institutional Review Board approval, volunteers with no prior history of nephrolithiasis were recruited. Each participant was randomized initially to either the coconut water or the water phase of the study. Participants kept meticulous food and fluid intake logs during the first phase of the study and were asked to replicate that diet for the second phase. For each phase the participant consumed 2L of either Taste of Nirvana® pure coconut water or tap water daily for four days. Participants were not restricted to consume additional fluid of their choice during their assigned study phase. During days 3 and 4 of each phase the participant collected a 24-hour urine specimen. Coconut water citrate and malate content were measured and were used along with the beverage pH to calculate the total alkali content of the coconut water. Supersaturation levels were calculated using Equil2. Nonparametric paired analysis using the Wilcoxon test was performed for statistical analysis.

Results

There were 4 adult male and 4 adult female participants. Each individual's 24-hour urine collection had a creatinine excretion within 20% of the mean for each subject's four samples corroborating that all samples were collected properly. The two samples from each phase for each individual were averaged. The coconut water itself was also analyzed and it was calculated to have a total alkali content of 13.8 mEq/L. Consumption of coconut water significantly increased urinary citrate (29%, p=0.02), urinary potassium (130%, p=0.01), and urinary chloride (37%, p=0.03), without affecting urine pH (p=0.16) or volume beyond that of tap water (p=1.00).

Conclusions

Coconut water consumption increases urinary potassium, chloride, and citrate in nonstone forming individuals.

Effectiveness of Citrus Fruits on Helicobacter pylori

It is known that Helicobacter pylori infection is associated with chronic gastritis, peptic ulcer, and gastric carcinoma. Due to the increased side effects of the treatment regimens and the development of antimicrobial resistance, a number of natural compounds have been tested as potential alternatives. In this review, we will examine the current knowledge on the effect of Citrus fruits and their derivatives against H. pylori, highlighting the remaining outstanding questions on the development of novel therapeutic strategies.

Effect of potassium citrate supplement on stone recurrence before or after lithotripsy: systematic review and meta-analysis

This meta-analysis summarizes the available evidence on the effectiveness of citrate supplement for preventing the recurrence of nephrolithiasis in patients undergoing extracorporeal shock wave lithotripsy (SWL). Electronic searches were conducted using Medline-PubMed, Web of Science, Embase, BVS (Scielo, Lilacs), and Google Scholar literature databases. The authors worked in pairs to select studies that met the following criteria: randomized controlled trials that were conducted in adults and assessed the effect of potassium citrate supplement before or after SWL therapy for urolithiasis. Our primary aim was to asses the stone-free rate among the groups included in the studies. Fixed effect was used in the meta-analysis with 95% confidence interval (95% CI). Heterogeneity was analyzed by the I ² value. A total of 2505 references were initially selected. Of those, four were subjected to meta-analysis contributing five samples. These four studies included 374 participants who were followed for a period of 12 months after SWL. Mean potassium citrate dosage was approximately 55 mEq/day (18 mmol). The results showed that citrate supplement significantly protected against the recurrence of nephrolithiasis during 1 year after SWL [RR; 95% CI 0.21 (0.13, 0.31)]. The heterogeneity was not significant across the analyzed studies (p = 0.224). The quality of the analyzed studies was generally low. The available evidence shows that citrate supplement effectively reduces the recurrence of nephrolithiasis in patients undergoing SWL. However, statistical analysis of a larger trial conducted with methodological rigor is warranted.

Analysis of biologically active oxyprenylated ferulic acid derivatives in Citrus fruits

4'-Geranyloxyferulic (GOFA) and boropinic acid have been discovered during the last decade as interesting phytochemicals having valuable pharmacological effects as cancer chemopreventive, anti-inflammatory, neuroprotective, and anti-Helicobacter pylori agents. A reverse-phase HPLC-UV/Vis method for the separation and quantification of the title oxyprenylated ferulic acid derivatives in extracts obtained from peels of nine edible Citrus and Fortunella fruits was successfully applied. Concentration values showed a great variation between the different species, being orange (C. sinensis) the fruit richest in GOFA (0.141 ± 0.011 mg/g of exocarp fresh weight) and kumquat (Fortunella japonica) the one in which boropinic acid was recorded as the most abundant phytochemical (0.206 ± 0.002 mg/g of exocarp fresh weight). Both secondary metabolites were not detected only in three species. The set-up methodology showed limits of quantification (LOQ) values, that were able to selectively quantify both GOFA and boropinic acid. Results described herein depict a potential chemopreventive dietary feeding role for the Rutaceae spp. under investigation.

Assessment of mineral intake by kidney stone patients of Kangra District, Himachal Pradesh with respect to their gender, age and income

OBJECTIVES

To assess the family history of stones and association of mineral intake with gender, age and income of kidney stone patients.

METHODS

A total of 130 kidney stone patients were selected randomly from Kangra district of Himachal Pradesh and family history of stones and mineral intake was assessed.

RESULTS

Out of selected patients, majority (80.77 %) were first time stone sufferers. There was significant (at 1 % level) association between family history of kidney stone patients with respect to gender of patients. Further study revealed that the intake of sodium, calcium, magnesium and phosphorous was higher than recommended dietary allowances (RDA). Among male patients, the intake of sodium, calcium and magnesium was higher for age group III (above 45 y) and intake of potassium and phosphorous was higher for age group I. In female kidney stone patients, intake of sodium, calcium and phosphorous was high for age group II, intake of potassium was high in case of age group I and intake of magnesium was high for age group III. Regression studies revealed that there was significantly higher intake of calcium and phosphorous by male kidney stone patients than female kidney stone patients. With the increase in age, the intake of calcium and phosphorous decreased.

CONCLUSIONS

Assessment of mineral intake is necessary to enable the health care providers, to give advice and suggestions to the patients to carry out preventive measures in reducing the risk of prevalence of kidney stones in this area and further advice to the suffering patients to prevent the recurrence of stone formation.

Metabolic evaluation in patients with nephrolithiasis: A report from Isfahan, Iran

Background:

Nephrolithiasis is a major public health problem worldwide. In recent years, growing evidence suggest that this disease may originate from underlying metabolic disorders. This is the first study that reports the frequency of different metabolic abnormalities among patients with nephrolithiasis in Isfahan, a large central province of Iran.

Materials and Methods:

From the time period between March 2009 and August 2010, 437 nephrolithiasis patients in Isfahan province enrolled in this study. Metabolic evaluation was performed by obtaining a 24-hours urine sample and fasting venous blood draw. We analyzed urine samples for volume, creatinine, calcium, citrate, oxalate, uric acid, sodium, and cystine. Fasting blood samples were assessed for serum calcium, phosphorus, sodium, potassium, uric acid, albumin, creatinine and blood urea nitrogen.

Results:

The mean age was 46 ± 13.8 years (rang: 18-87). Nearly 50% were first time stone formers. The most common metabolic abnormalities were hypocitraturia (40.5%) and hypernatriuria (31.8%) that was followed by hyperoxaluria (28.8%). Hypercalciuria was detected only in 9.2% of the cases.

Conclusion:

Although, high calcium excretion was the most frequent metabolic derangement in several similar studies, in our province with considerably high prevalence of vitamin D deficiency, it is not frequent among nephrolithiasis patients. Instead, other metabolic risk factors were in higher frequencies.

Alkaline citrate reduces stone recurrence and regrowth after shockwave lithotripsy and percutaneous nephrolithotomy

OBJECTIVE

To evaluate the preventive effects of alkaline citrate on stone recurrence as well as stone growth post-ESWL or PCNL in patients with calcium-containing stones.

MATERIALS AND METHODS

A total of 76 patients with calcium calculi who were stone-free or had residual stones less than 4 mm following ESWL and PCNL were enrolled. All patients were independently randomized into two groups. The treated group (N = 39) was given 81 mEq per day of oral potassium-sodium citrate (27 mEq three times a day), and the untreated group (N = 37) serving as controls. Blood, twenty-four hour urine analysis, and plain KUB were measured and compared at the baseline and after 12 months.

RESULTS

At baseline, hypocitraturia was found in 20 of 39 patients (46.05%) of Group I and 15 of 37 patients (40.5%) of Group II. At 12 months, hypocitraturia was found in 3 of 39 (7.69%) and 14 of 37 (37.83%) of Group I and Group II, respectively (p = 0.007). At the 12 month follow-up, of the stone-free group, 92.3% of the treated group and 57.7% of the control group were still stone free. Of the residual stone group, 30.8% and 9.1% of treated and control group were stone-free, respectively. The increased stone size found in 7.7%) and 54.5%) of treated and control groups, respectively.

CONCLUSION

Sodium-potassium citrate provides positive effects on stone-forming activities in calcium stone patients suffering from urolithiasis following treatment with ESWL and PCNL procedures at the 12-month follow-up.

Medical management of renal stone

Kidney stone is a common clinical problem faced by clinicians. The prevalence of the disease is increasing worldwide. As the affected population is getting younger and recurrence rates are high, dietary modifications, lifestyle changes, and medical management are essential. Patients with recurrent stone disease need careful evaluation for underlying metabolic disorder. Medical management should be used judiciously in all patients with kidney stones, with appropriate individualization. This chapter focuses on medical management of kidney stones.

Urine risk factors in children with calcium kidney stones and their siblings

Calcium nephrolithiasis in children is increasing in prevalence and tends to be recurrent. Although children have a lower incidence of nephrolithiasis than adults, its etiology in children is less well understood; hence, treatments targeted for adults may not be optimal in children. To better understand metabolic abnormalities in stone-forming children, we compared chemical measurements and the crystallization properties of 24-h urine collections from 129 stone formers matched to 105 non-stone-forming siblings and 183 normal, healthy children with no family history of stones, all aged 6 to 17 years. The principal risk factor for calcium stone formation was hypercalciuria. Stone formers have strikingly higher calcium excretion along with high supersaturation for calcium oxalate and calcium phosphate, and a reduced distance between the upper limit of metastability and supersaturation for calcium phosphate, indicating increased risk of calcium phosphate crystallization. Other differences in urine chemistry that exist between adult stone formers and normal individuals such as hyperoxaluria, hypocitraturia, abnormal urine pH, and low urine volume were not found in these children. Hence, hypercalciuria and a reduction in the gap between calcium phosphate upper limit of metastability and supersaturation are crucial determinants of stone risk. This highlights the importance of managing hypercalciuria in children with calcium stones.

Improved methodology to induce hyperoxaluria without treatment using hydroxyproline

The use of hydroxyproline (HP) to generate hyperoxaluria in the rat is a problem because it is impossible to separate the effect of oxalate on renal injury from the effects of HP and the large array of metabolic intermediates formed when HP is converted to oxalate. Previously, the Dahl salt-sensitive (SS) and Brown Norway (BN) rat strains were studied to determine genetic control of resistance or susceptibility to HP-induced renal injury and crystal deposition. To develop a better model to induce hyperoxaluria without causing injury from HP metabolites, animals were fed a diet containing various levels of added oxalate (0, 1, 2, 3, or 5%). After 5 weeks rats were killed and the kidneys were removed for microscopic evaluation of tubule changes and crystal deposition. The 3 and 5% oxalate-fed groups had a substantial increase in urine oxalate, about 50 and 140 μmol/g body weight over controls, respectively. Both the SS and BN 3% oxalate-fed animals showed only slightly elevated tubule area and no crystal deposition. However, BN animals fed 5% oxalate had a dramatic increase in their percent tubule areas compared to control BN rats and treated SS rats. Crystal deposition in the kidneys was only observed in the 5% oxalate-fed groups. The BN kidneys demonstrated a threefold higher crystal deposition compared to oxalate-fed SS rats. We conclude that oxalate-supplemented food is a better method of producing hyperoxaluria in the rat than using HP which may introduce metabolic intermediates injurious to the kidney.

Dietary therapy for patients with hypocitraturic nephrolithiasis

Citrate is an inhibitor of urinary stone formation. Clinical and in vitro data suggest that increasing urine citrate levels will decrease the precipitation of calcium stones. Historically, low urinary citrate has been treated with oral potassium citrate or sodium citrate supplementation, but recent studies have shown the potential of dietary interventions to raise urine citrate levels. Dietary therapy with commercial or homemade beverages is attractive to patients who would prefer nonpharmacological intervention. To date, several drinks have shown promise but no single beverage has been found to consistently raise urine citrate levels in a reproducible fashion. Further research is necessary to develop the ideal dietary therapy for hypocitraturic calcium nephrolithiasis.

Laterality of nephrocalcinosis in kidney stone formers with severe hypocitraturia

OBJECTIVE To examine the hypothesis that the distribution of nephrocalcinosis in patients with severe hypocitraturia should be symmetric. PATIENTS AND METHODS Patients with profound hypocitraturia defined as a 24-h urine citrate < 50 mg at the time of initial presentation were identified from the metabolic stone clinic database at our academic medical center. Two independent blinded reviewers evaluated all of the abdominal radiographs for the segmental distribution of macroscopic nephrocalcinosis. RESULTS A total of 44 patients met study criteria, with an equal distribution of males and females and a mean age of 55.4 ± 13.7 years. Mean urinary citrate was 28 ± 11 mg/day. Nephrocalcinosis was present in at least one renal segment in 22 patients (50%). Of the 22 patients with nephrocalcinosis, 9 patients (41%) had unilateral nephrocalcinosis and 13 patients (59%) had bilateral nephrocalcinosis. Of the 35 kidneys with nephrocalcinosis, 14 kidneys (40%) had nephrocalcinosis in only one renal segment, 13 kidneys (37%) had nephrocalcinosis in two segments and eight kidneys (23%) had nephrocalcinosis involving all three segments. CONCLUSIONS Despite the systemic nature of severe hypocitraturia, nephrocalcinosis is frequently asymmetric and focal in nature. This suggests that local factors intrinsic to the renal medullary interstitium, such as vascular injury, must play a role in the formation of nephrocalcinosis. Further study to elucidate these intrinsic local factors may further improve the treatment and prevention of urinary stone disease.

Nutritional aspect of nephrolithiasis

Nephrolithiasis is associated with a variety of abnormalities in urinary composition. These abnormal urinary risk factors are due to dietary indiscretions, physiological-metabolic disturbances or both. Stone disease is morbid and costly, and the recurrence rates may be as high as 30-50% after 5 years. Efforts to prevent stone formation are, therefore, essential. Dietary factors play an important role in kidney stone formation. Tailored dietary recommendations based on metabolic evaluation should be offered to patients for the prevention of recurrence of stone formation. Dietary intervention and subsequent evaluations of therapeutic efficacy should be based on results from multiple 24-h urine collections. Urine flow of >1 ml/kg/h almost eliminates the risk of supersaturation for calcium oxalate, calcium phosphate and uric acid, thus protecting from the formation of corresponding kidney stones. In patients with cystenuria, the required urine flow may even be higher and, in cases such as primary xanthinuria, high fluid intake is required. Milk intake in these patients should be within the RDA of calcium and protein. In children, recommendation of a high fluid intake has only limited success. Nevertheless, each patient should be advised about adequate fluid intake to increase urine volume in accordance with body size. Although children with hypocitraturia may benefit from therapeutic agents that raise the urine citrate concentration, all children bearing residual fragments should be counseled on adequate fluid intake along with potassium citrate treatment to prevent stone regrowth or formation.

Citrate, oxalate, sodium, and magnesium levels in fresh juices of three different types of tomatoes: evaluation in the light of the results of studies on orange and lemon juices

Fruit and vegetable juices containing citrate may be recommended as an alternative in mild to moderate level hypocitraturic calcium stone formers who cannot tolerate pharmacological treatment. Tomato has been proved a citrate-rich vegetable. Tomato juice usage as citrate sources in hypocitraturic recurrent stone formers were evaluated in the light of the results of studies on orange and lemon juices. Ten 100 ml samples were prepared from three different tomato types processed through a blender. These samples were examined in terms of citrate, oxalate, calcium, magnesium, and sodium contents. No difference was detected between the parameters tested in three different tomato juices. Fresh tomato juice may be useful in hypocitraturic recurrent stone formers due to its high content of citrate and magnesium, and low content of sodium and oxalate. As the three different types of tomatoes did not differ in terms of citrate, magnesium, sodium, and oxalate content, they may be useful for clinical use if also supported by clinical studies.

Changes in urinary stone risk factors in hypocitraturic calcium oxalate stone formers treated with dietary sodium supplementation

PURPOSE

We investigated the effects of supplemental dietary sodium on risk factors for urinary stone disease in stone forming patients with hypocitraturia.

MATERIALS AND METHODS

Ten patients diagnosed with recurrent isolated hypocitraturic calcium urolithiasis were identified. Baseline 24-hour urinalysis was performed with patients on their regular diet, including citrate replacement with 20 mEq potassium citrate 3 times per day. Strict daily dietary logs were kept for a 7-day period, during which patients had normal oral intake and potassium citrate replacement. Patients then received supplemental sodium chloride for 1 week (1 gm orally 3 times per day), in addition to their regular diets and potassium citrate supplementation. Dietary logs were continued and 24-hour urinalysis was performed at the end of 1 week of supplemental sodium. Risk factors for urinary stone disease were compared using the Student t test and ANOVA.

RESULTS

Two patients were unable to comply with sodium supplementation based on 24-hour urinalysis and, therefore, they were excluded from study. The remaining 8 patients were analyzed. Patients on supplemental dietary sodium demonstrated significantly increased mean urinary voided volume (933 ml per day above baseline, p <0.05) and mean urinary sodium excretion (66 mEq per day above baseline, p <0.05). There was no statistically significant change in urinary calcium, oxalate or uric acid. The urinary supersaturation relative risk ratio decreased for calcium oxalate stones (0.93 vs 0.63, p <0.05), while those of brushite, struvite and uric acid were not different before vs after supplemental sodium.

CONCLUSIONS

Dietary sodium supplementation resulted in an increased voided urine volume and decreased the relative risk supersaturation ratio for calcium oxalate stones in patients with a history of hypocitraturic calcium oxalate nephrolithiasis. Urinary calcium excretion as well as other urine parameters that are risk factors for nephrolithiasis was not changed. Sodium restriction may be inappropriate in patients with hypocitraturia and recurrent urinary stones. Sodium supplementation may be beneficial in these patients because it results in voluntary increased fluid intake.

Assessment of citrate concentrations in citrus fruit-based juices and beverages: implications for management of hypocitraturic nephrolithiasis

BACKGROUND AND PURPOSE

Dietary intake of citrate in the form of citrus juices (eg, lemonade, orange juice) will enhance urinary citrate excretion, a valuable benefit for patients with hypocitraturic calcium oxalate nephrolithiasis. While information on citrate concentrations in select citrus juices is available, data on citrate concentrations of commercially available beverages (juice and otherwise) are limited. Using nuclear magnetic resonance spectroscopy (1H NMR), we report citrate concentrations of several beverages to help guide dietary recommendations aimed at increasing urinary citrate excretion and correcting hypocitraturia.

METHODS

Citrate concentrations of a squeezed lemon, several fruit juices, and common beverages were measured using 1H NMR. Spectra for each sample were obtained in duplicate; citrate peak was identified, measured, and quantified and compared with the citrate concentration in the juice of 1 medium lemon.

RESULTS

Quantitative analysis revealed the highest concentration of citrate was in grapefruit juice (64.7 mmol/L), followed in decreasing concentrations by lemon juice (47.66 mmol/L), orange juice (47.36 mmol/L), pineapple juice (41.57 mmol/L), reconstituted lemonade (38.65 mmol/L), lemonade flavored Crystal Light (38.39 mmol/L), ready to consume not from concentrate lemonade (38.24 mmol/L), cranberry juice (19.87 mmol/L), lemon-flavored Gatorade (19.82 mmol/L), homemade lemonade (17.42 mmol/L), Mountain Dew (8.84 mmol/L), and Diet 7Up (7.98 mmol/L), respectively.

CONCLUSIONS

According to 1H NMR, all of the tested "natural" citrus juices have high concentrations of citrate (38.3-67.4 mmol/L), with grapefruit juice having the highest concentration of the beverages chosen. Lemonade flavored Crystal Light had the highest concentration of citrate in the nonjuice category of tested beverages. In patients with mild to moderate hypocitraturia, dietary supplementation with citrus-based juices may be an effective alternative to medical management while not requiring large serving sizes. Further prospective studies are warranted to evaluate the clinical significance of these findings.

Citrate levels in fresh tomato juice: a possible dietary alternative to traditional citrate supplementation in stone-forming patients

OBJECTIVES

To detect citrate levels in fresh tomato juice, to reveal whether it can be studied for prevention of recurrent hypocitraturic nephrolithiasis.

METHODS

Juices of tomato, orange, lemon, and mandarin were extracted and blended with a hand blender, and 10 samples of 100 mL were taken from each. Citrate, oxalate, calcium, phosphorus, magnesium, sodium, potassium, chloride, and pH levels were examined in these. The same variables were re-evaluated after the samples were stored at +4 degrees C for 1 week.

RESULTS

In fresh tomato juice, higher citrate and magnesium levels as well as lower sodium and oxalate levels were detected as compared with the other juices. No differences were observed with regard to all variables among fresh orange, lemon, and mandarin juices. The level of citrate in the fresh tomato juice was higher at a statistically significant level than that in tomato juice that was stored for 1 week. The amount of oxalate increased in stored tomato juice.

CONCLUSIONS

Fresh tomato juice is considered a rich source of citrate. Furthermore, a high level of magnesium and a low level of sodium and oxalate content were detected in fresh tomato juice, the usability of which in recurrent hypocitraturic nephrolithiasis can be investigated in clinical studies.

Pharmacological management of renal colic in the older patient

Renal colic affects up to 12% of the population. Initial management of most patients is expectant. Acute symptom management of renal colic is best accomplished with a combination of parenteral opioids and NSAIDs. The elderly patient with a kidney stone should be screened for contraindications to NSAID therapy, such as renal failure or previous peptic ulcer disease. Use of parenteral opioids is often necessary during the acute setting, and downward-adjusted doses and monitoring are necessary to prevent associated confusion and respiratory depression. Novel therapy with desmopressin may also be effective for symptom control at the initial presentation, without the adverse effects of opioids or NSAIDs. However, use of desmopressin in the elderly must be undertaken cautiously, given the potential adverse effects of this agent. Many small, distal ureteral stones are treated initially with watchful waiting for the first 2-4 weeks after presentation. The patient should have effective, non-parenteral analgesics for use at home. Included in these agents are oral or suppository NSAIDs and oral opioids. Medical expulsion therapy with alpha-adrenoceptor antagonists or calcium channel antagonists is efficacious. alpha-Adrenoceptor antagonists such as the alpha(1A/)(1)(D)-selective tamsulosin are well tolerated in the elderly and increase the rate of spontaneous stone passage by approximately 50% for small distal stones. These agents also appear to decrease the severity of renal colic. Corticosteroids and calcium channel antagonists are also effective but their use in the elderly is not recommended as first-line therapy.

Nephrolithiasis in identical twins: the impact of nature vs nurture

OBJECTIVE

To assess possible underlying metabolic abnormalities in three sets of monozygotic twins, to evaluate the interplay among the factors of kidney stone formation, a complex multifactorial process influenced by environmental, genetic and anatomical factors.

PATIENTS AND METHODS

Three sets of identical twins with either cystine or calcium oxalate stones were identified. Demographic data, medical histories and the results of 24-h urine testing, with samples collected on self-selected diets, were reviewed and analysed.

RESULTS

The cystinuric twins had very similar cystine excretion rates, while stone activity was significantly more pronounced in one. Metabolic abnormalities were concordant in one set of twins with calcium oxalate stones, both being hypercalciuric and hyperuricosuric. However, metabolic abnormalities were discordant in the other pair, one twin with hypercalciuria and the other with hypocitraturia. Two of the three pairs had low urinary volume.

CONCLUSIONS

These results support previous observations that environmental, genetic and potentially, anatomical factors play roles in kidney-stone formation. Additional controlled studies of monozygotic stone-forming twins might help to define the interplay between environmental and genetic factors, and allow the identification of susceptibility genes involved in stone generation.

Long-term lemonade based dietary manipulation in patients with hypocitraturic nephrolithiasis

PURPOSE

Citrus fruits and juices are a known natural source of dietary citrate. Of all the citrus juices, lemon juice appears to have the highest concentration of citrate. Therefore, lemonade therapy has been proposed as a potential treatment for patients with hypocitraturia. We retrospectively evaluated the impact of long-term lemonade therapy on urinary metabolic parameters and stone formation in patients with hypocitraturic nephrolithiasis.

MATERIALS AND METHODS

A total of 32 patients were identified as being on long-term lemonade therapy for hypocitraturic nephrolithiasis. The 11 patients on lemonade therapy who met the entrance criteria for evaluation were compared to an age and sex matched control group of patients treated with oral slow release potassium citrate. Pre-therapy and post-therapy urinary parameters were recorded for both groups. The effect of lemonade therapy on stone burden and stone formation rate was calculated. New stone formation was defined as passage, surgical removal or appearance of new stones, or an increase in the size of existing stones on radiographic imaging.

RESULTS

Four males and 7 females (mean age 52.7 years) were treated with lemonade therapy for a mean of 44.4 months. The control group consisted of 4 males and 7 females (mean age 54.5 years) treated with potassium citrate for a mean of 42.5 months. Of the 11 patients on lemonade 10 demonstrated increased urinary citrate levels (mean increase +383 mg per day, p <0.05). All potassium citrate therapy subjects demonstrated an increase in urinary citrate (mean increase +482 mg per day, p <0.0001). Mean pretreatment and posttreatment stone burden in the lemonade group was 37.2 and 30.4 mm(2), respectively (p >0.05). During lemonade therapy the stone formation rate decreased from 1.00 to 0.13 stones per patient per year (p >0.05).

CONCLUSIONS

Due to its significant citraturic effect, lemonade therapy appears to be a reasonable alternative for patients with hypocitraturia who cannot tolerate first line therapy. Future study in the form of a prospective, randomized trial is needed to validate these findings.

Renal lithiasis and nutrition

Renal lithiasis is a multifactorial disease. An important number of etiologic factors can be adequately modified trough diet, since it must be considered that the urine composition is directly related to diet. In fact, the change of inappropriate habitual diet patterns should be the main measure to prevent kidney stones. In this paper, the relation between different dietary factors (liquid intake, pH, calcium, phosphate, oxalate, citrate, phytate, urate and vitamins) and each type of renal stone (calcium oxalate monohydrate papillary, calcium oxalate monohydrate unattached, calcium oxalate dihydrate, calcium oxalate dihydrate/hydroxyapatite, hydroxyapatite, struvite infectious, brushite, uric acid, calcium oxalate/uric acid and cystine) is discussed.

The effect of calcium channel blockers on stone regrowth and recurrence after shock wave lithotripsy

We evaluated the possible effects of a calcium entry blocking agent "verapamil" on new stone formation and/or regrowth of residual fragments after shock wave lithotripsy (SWL) during long-term follow-up (>30 months) and compared the results with the success rates of adequate fluid intake. A total of 70 patients treated with SWL were randomly divided into three different groups, in the first two of which the patients received different preventive measures with respect to stone recurrence and/or regrowth. While 25 patients received a calcium channel blocking agent, verapamil hydrochloride, beginning 3 days before SWL and continued 4 weeks after the procedure, an additional 25 patients were put in an enforced fluid intake program and the remaining 20 patients received no specific medication and/or measure apart from close follow-up. Patients were followed regularly with respect to the clearance/regrowth of the residual fragments and that of new stone formation during long-term follow-up (within a mean follow-up of 30.4 months). The overall stone recurrence rate was 14% (10/70). Of the patients who became stone free (12/25, 48%) in group I, only one patient (1/12, 8.3%) showed a new stone formation during long-term follow-up. The figure was 40% (4/10) in group II patients and 55% (5/9) in group III patients receiving no specific medication. Regarding the residual stone fragments (<5 mm) after SWL, again high fluid intake was found to be the most effective on stone regrowth rates (2/13, 15.3%). Patients treated with verapamil also had acceptable regrowth rates (3/15, 20%). Finally, verapamil treatment significantly improved the clearance of residual fragments; while 7 out of 15 patients with residual fragments passed these particles successfully, (46.5%) in this group; these figures were 46% (6/13) and 18% (2/13) in the remaining groups. Residual fragments located in lower calyces demonstrated a poor clearance rate with higher regrowth rates. Verapamil administration was found to be effective enough to limit the regrowth of residual fragments and also to facilitate residual fragment clearance after SWL. Patients receiving this medication seemed to pass the retained fragments easily in a shorter time than the others.