Nutrition and Kidney Stone Disease.

The prevalence of kidney stone disease is increasing worldwide. The recurrence rate of urinary stones is estimated to be up to 50%. Nephrolithiasis is associated with increased risk of chronic and end stage kidney disease. Diet composition is considered to play a crucial role in urinary stone formation. There is strong evidence that an inadequate fluid intake is the major dietary risk factor for urolithiasis. While the benefit of high fluid intake has been confirmed, the effect of different beverages, such as tap water, mineral water, fruit juices, soft drinks, tea and coffee, are debated. Other nutritional factors, including dietary protein, carbohydrates, oxalate, calcium and sodium chloride can also modulate the urinary risk profile and contribute to the risk of kidney stone formation. The assessment of nutritional risk factors is an essential component in the specific dietary therapy of kidney stone patients. An appropriate dietary intervention can contribute to the effective prevention of recurrent stones and reduce the burden of invasive surgical procedures for the treatment of urinary stone disease. This narrative review has intended to provide a comprehensive and updated overview on the role of nutrition and diet in kidney stone disease.

Diet and Kidney Stones: The Ideal Questionnaire.

Diet frequently contributes to patients' urinary stone disease. It is important to determine when this is the case and when it is not, as failure to do so may delay the implementation of other, more appropriate therapies. When diet is thought to be involved, one of two approaches may be taken: (1) provide a general list of all possible dietary factors that influence the risk for all types of stones and let the patient decide which dietary change(s) are needed; or (2) prescribe specific modifications that address each patient's need for change and their personal characteristics (i.e., urinary risk factors, type(s) of stones they have formed, dietary preferences, nutrient needs, etc.). The latter of these approaches is "minimally invasive" and is thus consistent with the goal of other therapies. However, this approach requires a rigorous appraisement of each patient's diet and linkage, when possible, to urinary and other stone risk factors. When the collaboration of a registered dietitian nutritionist or other nutrition professional experienced in dietary assessment is not available, screeners or questionnaires may be useful. Unfortunately, there is no such tool that is validated for identifying dietary stone risk factors. The development of a brief, 40-item, stone-specific food screener is described. While further validation is needed, it may provide the basis for a standardized instrument that could be used more broadly; desired features of such an instrument are described. Patient Summary: Personalized nutrition therapy is useful in mitigating the effects or recurrence risk of many chronic diseases. It is also useful in stone disease, a condition with highly variable risk expression, even among patients who form the same types of stones. A standardized and validated stone-specific dietary assessment tool would be valuable in clinical management and in research studies involving the description of patients' diets and dietary intervention.

Simple dietary advice targeting five urinary parameters reduces urinary supersaturation in idiopathic calcium oxalate stone formers.

Among 208 kidney stone patients referred within 2 years, 75 patients (66 men, nine women) with truly idiopathic calcium oxalate stones (ICSF) were recruited. Dietary advice (DA) aimed at (1) urine dilution, (2) reduced crystallization promotion (lowering oxalate), and (3) increased crystallization inhibition (increasing citrate). We recommended higher intakes of fluid and calcium with meals/snacks (reducing intestinal oxalate absorption) as well as increased alkali and reduced meat protein (acid) for increasing urinary citrate. The intended effects of DA were elevations in urine volume, calcium (U-Ca) and citrate (U-Cit) as well as reductions in oxalate (U-Ox) and uric acid (U-UA). We retrospectively calculated an adherence score (AS), awarding + 1 point for parameters altered in the intended direction and - 1 point for opposite changes. Calcium oxalate supersaturation (CaOx-SS) was calculated using Tiselius' AP(CaOx) index EQ. DA induced changes (all p < 0.0001) in urine volume (2057 ± 79 vs. 2573 ± 71 ml/day) and U-Ca (5.49 ± 0.24 vs. 7.98 ± 0.38 mmol/day) as well as in U-Ox (0.34 ± 0.01 vs. 0.26 ± 0.01 mmol/day) and U-UA (3.48 ± 0.12 vs. 3.13 ± 0.10 mmol/day). U-Cit only tendentially increased (3.07 ± 0.17 vs. 3.36 ± 0.23 mmol/day, p = 0.06). DA induced a 21.5% drop in AP(CaOx) index, from 0.93 ± 0.05 to 0.73 ± 0.05 (p = 0.0005). Decreases in CaOx-SS correlated with AS (R = 0.448, p < 0.0005), and highest AS (+ 5) always indicated lowering of CaOx-SS. Thus, simple DA can reduce CaOx-SS which may be monitored by AS.

The Efficacy of Polyunsaturated Fatty Acids as Protectors against Calcium Oxalate Renal Stone Formation: A Review.

In the pathogenesis of hypercalciuria and hyperoxaluria, n-6 polyunsaturated fatty acids (PUFAs) have been implicated by virtue of their metabolic links with arachidonic acid (AA) and prostaglandin PGE2. Studies have also shown that n-3 PUFAs, particularly those in fish oil-eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)-can serve as competitive substrates for AA in the n-6 series and can be incorporated into cell membrane phospholipids in the latter's place, thereby reducing urinary excretions of calcium and oxalate. The present review interrogates several different types of study which address the question of the potential roles played by dietary PUFAs in modulating stone formation. Included among these are human trials that have investigated the effects of dietary PUFA interventions. We identified 16 such trials. Besides fish oil (EPA+DHA), other supplements such as evening primrose oil containing n-6 FAs linoleic acid (LA) and γ-linolenic acid (GLA) were tested. Urinary excretion of calcium or oxalate or both decreased in most trials. However, these decreases were most prominent in the fish oil trials. We recommend the administration of fish oil containing EPA and DHA in the management of calcium oxalate urolithiasis.

Disentangling the Relationships Between the Renin-Angiotensin-Aldosterone System, Calcium Physiology, and Risk for Kidney Stones.

CONTEXT: Complex relationships between aldosterone and calcium homeostasis have been proposed. OBJECTIVE: To disentangle the influence of aldosterone and intravascular volume on calcium physiology. DESIGN: Patient-oriented and epidemiology studies. SETTING: Clinical research center and nationwide cohorts. PARTICIPANTS/INTERVENTIONS: Patient-oriented study (n = 18): Participants were evaluated after completing a sodium-restricted (RES) diet to contract intravascular volume and after a liberalized-sodium (LIB) diet to expand intravascular volume. Cross-sectional studies (n = 3755): the association between 24h urinary sodium and calcium excretion and risk for kidney stones was assessed. RESULTS: Patient-oriented study: compared to a RES-diet, a LIB-diet suppressed renin activity (LIB: 0.3 [0.1, 0.4] vs. RES: 3.1 [1.7, 5.3] ng/mL/h; P < 0.001) and plasma aldosterone (LIB: 2.0 [2.0, 2.7] vs. RES: 20.0 [16.1, 31.0] vs. ng/dL; P < 0.001), but increased calciuria (LIB: 238.4 ±â€…112.3 vs. RES: 112.9 ±â€…60.8 mg/24hr; P < 0.0001) and decreased serum calcium (LIB: 8.9 ±â€…0.3 vs. RES: 9.8 ±â€…0.4 mg/dL; P < 0.0001). Epidemiology study: mean urinary calcium excretion was higher with greater urinary sodium excretion. Compared to a urinary sodium excretion of < 120 mEq/day, a urinary sodium excretion of ≥220 mEq/day was associated with a higher risk for having kidney stones in women (risk ratio = 1.79 [95% confidence interval 1.05, 3.04]) and men (risk ratio = 2.06 [95% confidence interval 1.27, 3.32]). CONCLUSIONS: High dietary sodium intake suppresses aldosterone, decreases serum calcium, and increases calciuria and the risk for developing kidney stones. Our findings help disentangle the influences of volume from aldosterone on calcium homeostasis and provide support for the recommendation to restrict dietary sodium for kidney stone prevention.

Assessment of conservative dietary management as a method for normalization of 24-h urine pH in stone formers.

Low urine pH is a metabolic risk factor for stone formation. While medical therapy is typically prescribed (as urinary alkalinization), patients typically prefer dietary modifications. We aimed to assess capacity to alter urine pH with dietary management alone. We analyzed a retrospective cohort of stone formers seen between 2000 and 2015 with multiple 24-h urine collections (24hUC). Patients ≥ 18 years old with low urine pH (< 6.0) were included; those prescribed alkalinizing agents or thiazides were excluded. Demographic data, 24hUC parameters, and medications were abstracted. 24hUC was utilized to calculate gastrointestinal alkali absorption (GIAA). The primary outcome was urine pH ≥ 6.0 on second 24hUC. Predictors were selected utilizing multivariable logistic regression. The database consisted of 2197 stone formers; 224 of these met inclusion criteria. On second 24hUC, 124 (55.4%) achieved a favorable pH ≥ 6.0. On univariable analysis, a second pH ≥ 6.0 was associated with high initial pH, low initial sulfate, younger age, increase in citrate/GIAA/urine volume, and decrease in ammonium (P < 0.02). On multivariable analysis, high initial pH (OR = 23.64, P < 0.001), high initial GIAA (OR = 1.03, P = 0.001), lower initial sulfate (OR = 0.95, P < 0.001), increase in urine volume (OR = 2.19, P = 0.001), increase in GIAA (OR = 8.6, P < 0.001), increase in citrate (OR = 2.7, P = 0.014), decrease in ammonium (OR = 0.18, P < 0.001), and younger age (OR = 0.97, P = 0.025) were associated with a second pH ≥ 6.0. The analysis demonstrated a corrected AUC of 0.853. These data suggest that certain dietary recommendations (increases in urine volume, citrate, GIAA, and decreased acid load) may normalize urine pH in a select group of patients. This may allow urologists to counsel patients with low urine pH on possibility of success with dietary modification alone.

Dietary vinegar prevents kidney stone recurrence via epigenetic regulations.

BACKGROUND: Epidemiological evidence of over 9000 people suggests that daily intake of vinegar whose principal bioactive component is acetic acid is associated with a reduced risk of nephrolithiasis. The underlying mechanism, however, remains largely unknown. METHODS: We examined the in vitro and in vivo anti-nephrolithiasis effects of vinegar and acetate. A randomized study was performed to confirm the effects of vinegar in humans. FINDINGS: We found individuals with daily consumption of vinegar compared to those without have a higher citrate and a lower calcium excretion in urine, two critical molecules for calcium oxalate (CaOx) kidney stone in humans. We observed that oral administration of vinegar or 5% acetate increased citrate and reduced calcium in urinary excretion, and finally suppressed renal CaOx crystal formation in a rat model. Mechanism dissection suggested that acetate enhanced acetylation of Histone H3 in renal tubular cells and promoted expression of microRNAs-130a-3p, -148b-3p and -374b-5p by increasing H3K9, H3K27 acetylation at their promoter regions. These miRNAs can suppress the expression of Nadc1 and Cldn14, thus enhancing urinary citrate excretion and reducing urinary calcium excretion. Significantly these mechanistic findings were confirmed in human kidney tissues, suggesting similar mechanistic relationships exist in humans. Results from a pilot clinical study indicated that daily intake of vinegar reduced stone recurrence, increased citrate and reduced calcium in urinary excretion in CaOx stone formers without adverse side effects. INTERPRETATION: Vinegar prevents renal CaOx crystal formation through influencing urinary citrate and calcium excretion via epigenetic regulations. Vinegar consumption is a promising strategy to prevent CaOx nephrolithiasis occurrence and recurrence. FUND: National Natural Science Foundations of China and National Natural Science Foundation of Guangdong Province.

[Role of drinking and dietary factors in effective dissolution therapy and recurrence prevention of uric acid kidney stones].

The use of alkaline mineral waters leads to alkalization of urine and an increase in level of urinary citrate, which represent important factor inhibiting the formation of urinary stones. Combination of alkaline mineral waters with citrates facilitates the achievement of target urine pH level not only during dissolution therapy, but also during recurrence prevention. Alkalization of urine and reducing of the influence of alimentary factor dont preclude drug therapy. Patients should be counselled about complex strategies aimed to modifiable risk factors for urinary stone disease.

Emerging Mobile Platforms to Aid in Stone Management.

Nephrolithiasis is an increasingly common condition worldwide and mobile technology is revolutionizing how patients with kidney stone are being diagnosed and managed. Emerging platforms include software applications to increase adherence to stone prevention, mobile compatible hardware, online social media communities, and telemedicine. Applications and hardware specifically relevant to increasing hydration, diet modification, medication adherence, and rapid diagnosis (ie, mobile ultrasound and endoscopy) have the greatest potential to reduce stone recurrence and expedite treatment. Social media and online communities have also been rapidly adopted by patients and providers to promote education and support.

Hydroxycitrate: a potential new therapy for calcium urolithiasis.

Alkali supplements are used to treat calcium kidney stones owing to their ability to increase urine citrate excretion which lowers stone risk by inhibiting crystallization and complexing calcium. However, alkali increases urine pH, which may reduce effectiveness for patients with calcium phosphate stones and alkaline urine. Hydroxycitrate is a structural analog of citrate, widely available as an over-the-counter supplement for weight reduction. In vitro studies show hydroxycitrate has the capacity to complex calcium equivalent to that of citrate and that it is an effective inhibitor of calcium oxalate monohydrate crystallization. In fact, hydroxycitrate was shown to dissolve calcium oxalate crystals in supersaturated solution in vitro. Hydroxycitrate is not known to be metabolized by humans, so it would not be expected to alter urine pH, as opposed to citrate therapy. Preliminary studies have shown orally ingested hydroxycitrate is excreted in urine, making it an excellent candidate as a stone therapeutic. In this article, we detail the crystal inhibition activity of hydroxycitrate, review the current knowledge of hydroxycitrate use in humans, and identify gaps in knowledge that require appropriate research studies before hydroxycitrate can be recommended as a therapy for kidney stones.

Public Perceptions on the Influence of Diet and Kidney Stone Formation.

Introduction: Public awareness regarding the influence of diet on kidney stones is unknown. We sought to evaluate such perceptions among an unselected community cohort. Materials and Methods: A survey was created to assess perception of beverages/foods on risk of kidney stone formation. Surveys were distributed to attendees of a State Fair. Participants were categorized to determine the effect of stone history on prevention knowledge (no prior stone vs prior stone). Results: Seven hundred fifty-three participants completed the survey, including 264 (35%) with a prior stone. Participants with prior stones were less likely to believe stones were preventable compared to those without (56% vs 65%, p = 0.01). Appropriate perceptions regarding influence of diet on stones were highest for water (>90% of participants) and cola/salt/red meat (>50%). Fewer than half of respondents correctly identified the influence of the remaining 14 substances. On multivariable analysis, stone formers were more likely to correctly identify the influence of lemonade (odds ratio [OR] 2.09; 95% confidence interval [CI] 1.32-3.31), nuts (OR 2.60; 95% CI 1.60-4.23), and spinach (OR 5.06; 95% CI 2.89-8.86), but less likely to identify the influence of coffee (OR 0.43; 95% CI 0.23-0.82) and red meat (OR 0.52; 95% CI 0.23-0.59). Conclusion: Patients with prior stones hold different attitudes regarding the influence of certain foods and drinks on stone formation relative to the public. Such attitudes are not always correct, and as a group they are less likely to believe in dietary stone prevention. Such findings may indicate confusion among stone formers and highlight an opportunity for improved dietary counseling.

The Effect of Lemonade and Diet Lemonade Upon Urinary Parameters Affecting Calcium Urinary Stone Formation.

PURPOSE: To determine the effects of regular and diet lemonade upon urinary parameters affecting kidney stone formation. METHODS: In this prospective blinded crossover study, 12 healthy participants consumed either 2 L of regular or diet lemonade daily while on a standardized low sodium moderate calcium diet. Twenty four-hour urine collections were obtained at baseline on the controlled diet only and on days 4 and 5 of each treatment phase. There was a 1-week washout period between regular and diet lemonade treatments. Primary outcomes were urine citrate, pH, and volume determined by 24-hour urine collections. Secondary outcomes included the supersaturation of calcium oxalate, calcium phosphate, and uric acid. RESULTS: Urine volume was significantly higher with both regular and diet lemonade consumption compared with baseline values. Urinary citrate significantly increased from baseline with diet lemonade only. Urine pH was unchanged with both beverages. The supersaturation of calcium oxalate significantly decreased with diet lemonade only, whereas supersaturation of calcium phosphate decreased with both beverages. Daily consumption of 2 L of regular and diet lemonade resulted in an intake of 168.4 and 170.2 mEq of citrate but a total alkali intake of 12.2 and 16.0 mEq, respectively. Compared with diet lemonade, regular lemonade provided subjects with 805 additional calories and 225 g of sugar per day. CONCLUSIONS: Diet lemonade may provide a low-calorie sugar-free cost-effective option for decreasing the risk of recurrent calcium nephrolithiasis through a significant increase in urine volume, increase in urinary citrate, and reduction in supersaturation of calcium oxalate and calcium phosphate.

Can We Predict the Outcome of Oral Dissolution Therapy for Radiolucent Renal Calculi? A Prospective Study.

PURPOSE: We prospectively assessed the efficacy and the predictors of the success of oral dissolution therapy by alkalization for lucent renal calculi. MATERIALS AND METHODS: Patients with radiolucent renal stones were counseled to undergo oral dissolution therapy, which entails oral potassium citrate 20 mEq 3 times daily, 3 L daily fluid intake and a dietary regimen. The study primary end point was the achievement of a 6-month stone-free rate with oral dissolution therapy. The other end point was a change in stone surface area as measured by noncontrast computerized tomography at 3 and 6 months. RESULTS: Between February 2015 and January 2016 only 182 of the 212 eligible patients who agreed to participate were compliant with oral dissolution therapy and included in the final analysis. Mean stone surface area at enrollment was 1.3 cm (range 0.16 to 11.84). At 3 months 97 (53.2%), 65 (35.7%) and 20 (11.1%) patients were oral dissolution therapy responders (stone-free), partial responders and nonresponders, respectively. Oral dissolution therapy achieved a 6-month stone-free rate of 83%, including 97 and 54 patients after 3 and 6 months of oral dissolution therapy, respectively. On regression analysis the initial 3-month response to oral dissolution therapy (p = 0.001), lower stone density (p = 0.03) and higher urine pH 12 weeks after treatment (p = 0.01) independently predicted the oral dissolution therapy response at 6 months. CONCLUSIONS: Regardless of stone size, oral dissolution therapy was an effective treatment approach for lucent renal stones. The initial response to oral dissolution therapy after 3 months was the key factor in determining the potential oral dissolution therapy response after 6 months. In addition, treatment compliance in achieving the targeted urine pH and low stone density has an independent role in the oral dissolution therapy response.

Short-Term Changes in Urinary Relative Supersaturation Predict Recurrence of Kidney Stones: A Tool to Guide Preventive Measures in Urolithiasis.

PURPOSE: Kidney stone disease is characterized by a relatively high rate of recurrence. In our study we analyzed the association between relative supersaturation and the risk of stone recurrence. Additionally, we examined the association between the risk of recurrence and changes in relative supersaturation and urinary composition after 1 week of medical treatment. MATERIALS AND METHODS: We performed a post hoc analysis of data from a previously published randomized controlled trial comparing the effect of 2 diets in 120 men with recurrent calcium oxalate stones and hypercalciuria. Baseline and followup 24-hour urine parameters were used to calculate the relative supersaturation of calcium oxalate, calcium phosphate and uric acid using the EQUIL2, JESS and LithoRisk computer programs. Cox models were used to calculate the estimated association between each baseline relative supersaturation, and 1-week changes and the risk of recurrence during followup. RESULTS: During a 5-year followup 35 patients (34%) experienced recurrence. A reduction in calcium oxalate relative supersaturation at 1 week was significantly associated with a lower risk of recurrence using the EQUIL2 calculation (for every 10% reduction from baseline HR 0.92, 95% CI 0.86-1.00, p = 0.044). However, there was no association for relative supersaturation calculated by other methods or for the relative supersaturation of other salts. Changes in the 24-hour urine excretion of citrate, potassium and magnesium were significantly associated with a risk of recurrence. CONCLUSIONS: In recurrent stone formers with hypercalciuria baseline values and changes in the relative supersaturation of calcium oxalate may be associated with the risk of recurrence. Changes in urinary citrate, potassium and magnesium following dietary intervention may also be predictive.

Updates in the Metabolic Management of Calcium Stones.

PURPOSE OF REVIEW: Urinary risk factors, such as hypercalciuria, hypocitraturia, and hyperoxaluria, either in combination or alone, are associated with calcium stones. Dietary habits as well as underlying medical conditions can influence urinary risk factors. Evaluation of the conglomerate of patients' stone risks provides evidence for individualized medical management, an effective and patient-supported approach to prevention. RECENT FINDINGS: Many patients with stones desire prevention to avoid repeated surgical interventions. Yet, recent practice pattern assessments and health care utilization data show that many patients are rarely referred for metabolic evaluation or management. Innovations in metabolic management over the past decade have improved its effectiveness in reducing risk and preventing calcium stones. Although no new pharmacologic agents for calcium stone prevention have recently become available, there is relatively new thinking about some diet-based approaches. This review will synthesize current evidence to support individualized metabolic management of calcium stones.

Changes in urinary risk profile after short-term low sodium and low calcium diet in recurrent Swiss kidney stone formers.

BACKGROUND: Kidney stone disease is common in industrialized countries. Recently, it has attracted growing attention, because of its significant association with adverse renal outcomes, including end stage renal disease. Calcium-containing kidney stones are frequent with high recurrence rates. While hypercalciuria is a well-known risk factor, restricted intake of animal protein and sodium, combined with normal dietary calcium, has been shown to be more effective in stone prevention compared with a low-calcium diet. Notably, the average sodium intake in Switzerland is twice as high as the WHO recommendation, while the intake of milk and dairy products is low. METHODS: We retrospectively analyzed Swiss recurrent kidney stone formers (rKSF) to test the impact of a low-sodium in combination with a low-calcium diet on the urinary risk profile. In patients with recurrent calcium oxalate containing stones, we investigated both, the consequence of a low-sodium diet on urinary volume and calcium excretion, and the influence of a low-sodium low-calcium diet on urinary oxalate excretion. RESULTS: Of the 169 patients with CaOx stones, 49 presented with hypercalciuria at baseline. The diet resulted in a highly significant reduction in 24-h urinary sodium and calcium excretion: from 201 ± 89 at baseline to 128 ± 88 mmol/d for sodium (p < 0.0001), and from 5.67 ± 3.01 to 4.06 ± 2.46 mmol/d (p < 0.0001) for calcium, respectively. Urine volume remained unchanged. Notably, no increase in oxalate excretion occurred on the restricted diet (0.39 ± 0.26 vs 0.39 ± 0.19 mmol/d, p = 0.277). Calculated Psf (probability of stone formation) values were only predictive for the risk of calcium phosphate stones. CONCLUSION: A diet low in sodium and calcium in recurrent calcium oxalate stone formers resulted in a significant reduction of urinary calcium excretion, but no change in urine volume. In this population with apparently low intake of dairy products, calcium restriction does not necessarily result in increased urinary oxalate excretion. However, based on previous studies, we recommend a normal dietary calcium intake to avoid a potential increase in urinary oxalate excretion and unfavorable effects on bone metabolism in hypercalciuric KSFs.

Factors Associated with Compliance to Increased Fluid Intake and Urine Volume Following Dietary Counseling in First-Time Kidney Stone Patients.

OBJECTIVE: Increasing fluid intake to achieve a urine volume (UV) of >2.5 L/day decreases stone events. We assessed compliance rates and demographic and clinical variables associated with increased fluid intake and UV in patients with urolithiasis following dietary counseling. MATERIALS AND METHODS: In a retrospective study, patients with a low baseline UV (<2.5 L/day) on an initial 24-hour urine collection during metabolic stone evaluation were identified between 2010 and 2015. Patients received detailed standardized dietary counseling, including increasing fluid intake to >3 L/day and titrating it to achieve UV >2.5 L/day. A follow-up 24-hour urine collection was performed at 6 months (FU1) and 18 months (FU2) to assess compliance (UV >2.5 L/day) and predictors associated with it. RESULTS: Our cohort contained 363 patients, 53.4% men and 46.6% women. The mean UV of baseline, FU1, and FU2 urine collections was 1.63, 2.52, and 2.48 L, respectively. The compliance rate of obtaining UV of >2.5 L was 50.1% at 6 months. On logistic regression, male sex (odds ratio [OR] 3.27, 95% confidence interval [CI] 1.94, 5.52, p < 0.001), urolithiasis-related procedures such as ureteroscopy (OR 2.31, 95% CI 1.20, 4.42, p = 0.01) or percutaneous nephrolithotomy (OR 3.48, 95% CI 1.58, 7.63, p = 0.002), and baseline 24-hour UV >1 L (OR 3.00, 95% CI 1.02, 8.76, p = 0.04) were associated with greater odds of compliance. Age >58 years (OR 0.39, 95% CI 0.20, 0.75, p = 0.005) and presence of lower urinary tract symptoms (OR 0.50, 95% CI 0.26, 0.95, p = 0.03) were associated with lower odds of compliance. Ethnicity, body mass index, renal function, marital status, renal stone burden, stone type, and household income were not associated with compliance. CONCLUSIONS: In stone formers, compliance to fluid intake recommendations as measured by 24-hour UV is roughly 50%. Understanding risk factors for noncompliance, especially in at risk patients, can be used for quality improvement initiatives and reducing stone events.

Urolithiasis: evaluation, dietary factors, and medical management: an update of the 2014 SIU-ICUD international consultation on stone disease.

PURPOSE: The aim of this review was to provide current best evidence for evaluation, dietary, and medical management of patients with urolithiasis. METHODS: Literature addressing evaluation, dietary, and medical management of urolithiasis was searched. Papers were analyzed and rated according to level of evidence (LOE), whereupon a synthesis of the evidence was made. Grade of recommendation (GOR) was judged from individual clinical experience and knowledge of the evidence according to the Oxford Centre for Evidence-based Medicine. RESULTS: It is obvious that different stone diseases influence the life of stone-forming individuals very differently, and that evaluation and medical management should be personalized according to risk of recurrence, severity of stone disease, presence of associated medical conditions, and patient's motivation. With regard to evaluation, dietary and medical management of patients with urolithiasis evidence from the literature suggest that selective metabolic evaluation may lead to rational dietary and medical management. Statements based on LOE and GOR are provided to guide clinical practice. CONCLUSION: The provided evidence for evaluation of patients with urolithiasis aims at defining patients at high risk for recurrent/complicated stone disease. Based on this approach, evidence-based dietary and medical management regimes are suggested.

Pears and renal stones: possible weapon for prevention? A comprehensive narrative review.

Urinary stones have been recognized as a human disease since dawn of history and treatment of this condition is reported by Egyptian medical writings. Also, pears have a very long history, being one of the earliest cultivated fruit trees and also known for medicinal use. Urinary tract stone formation represents a common condition and also a significant burden for health care service, due also to possible frequent relapses. Furthermore, urinary stones have been reported to have relationship with different metabolic derangements, and appropriate diet could contribute to avoid or reduce urinary stone formation. Citrate is an inhibitor of crystal growth in the urinary system, and hypocitraturia represents a main therapeutical target in stone formers. Pears contain a significant amount of malic acid, a precursor of citrate, and have antioxidant activity as well. A diet supplemented with pears, and associated with low consumption of meat and salt could impact positively cardiometabolic risk and urinary tract stone formation. However, very few studies evaluated the impact of pears utilization on health, and none on urinary tract stone formation in particular. High content in malate could warrant protection against stone formation, avoiding patients at high risk to be compelled to assume a considerable and expensive amount of pills.