Nephrolithiasis is a common medical condition influenced by multiple environmental factors, including diet. Since nutritional habits play a relevant role in the genesis and recurrence of kidney ...stones disease, dietary manipulation has become a fundamental tool for the medical management of nephrolithiasis. Dietary advice aims to reduce the majority of lithogenic risk factors, reducing the supersaturation of urine, mainly for calcium oxalate, calcium phosphate, and uric acid. For this purpose, current guidelines recommend increasing fluid intake, maintaining a balanced calcium intake, reducing dietary intake of sodium and animal proteins, and increasing intake of fruits and fibers. In this review, we analyzed the effects of each dietary factor on nephrolithiasis incidence and recurrence rate. Available scientific evidence agrees on the harmful effects of high meat/animal protein intake and low calcium diets, whereas high content of fruits and vegetables associated with a balanced intake of low-fat dairy products carries the lowest risk for incident kidney stones. Furthermore, a balanced vegetarian diet with dairy products seems to be the most protective diet for kidney stone patients. Since no study prospectively examined the effects of vegan diets on nephrolithiasis risk factors, more scientific work should be made to define the best diet for different kidney stone phenotypes.
Uric acid nephrolithiasis (UAN) is an increasingly common disease in ethnically diverse populations and constitutes about 10% of all kidney stones. Metabolic syndrome and diabetes mellitus are ...accounted among the major risk factors for UAN, together with environmental exposure, individual lifestyle habits and genetic predisposition. The development and overt manifestation of UAN appears to stem on the background of insulin resistance, which acts at the kidney level by reducing urinary pH, thus hampering the ability of the kidney to generate renal ammonium in response to an acid load. Unduly acidic urinary pH and overt UAN are both considered renal manifestations of insulin resistance. The mechanisms underlying increased endogenous acid production and/or defective ammonium excretion are yet to be completely understood. Although the development of UAN and, more in general, of kidney stones largely recognizes modifiable individual determining factors, the rising prevalence of diabetes, obesity and accompanying metabolic disorders calls for the identification of novel therapeutic approaches and intervention targets. This review aims at providing an updated picture of existing evidence on the relationship between insulin resistance and UAN in the context of metabolic syndrome and in light of the most recent advancements in our understanding of its genetic signature.
•Metabolic syndrome (MetS) and uric acid nephrolithiasis (UAN) display a strong clinical association•UAN recognizes direct and indirect kidney-specific effects of insulin resistance as underlying pathophysiologic disease mechanisms•As far as it is currently understood, insulin resistance and UAN do not apparently share a major genetic basis•Further efforts are needed to untangle the genetic link, if any, between UAN and insulin resistance in the kidney.•The screening and prompt treatment initiation for the MetS-associated traits in patients presenting with UAN is warranted
Not all fluids may be equally beneficial for reducing the risk of kidney stones. In particular, it is not clear whether sugar and artificially sweetened soda increase the risk.
We prospectively ...analyzed the association between intake of several types of beverages and incidence of kidney stones in three large ongoing cohort studies. Information on consumption of beverages and development of kidney stones was collected by validated questionnaires.
The analysis involved 194,095 participants; over a median follow-up of more than 8 years, 4462 incident cases occurred. There was a 23% higher risk of developing kidney stones in the highest category of consumption of sugar-sweetened cola compared with the lowest category (P for trend=0.02) and a 33% higher risk of developing kidney stones for sugar-sweetened noncola (P for trend=0.003); there was a marginally significant higher risk of developing kidney stones for artificially sweetened noncola (P for trend=0.05). Also, there was an 18% higher risk for punch (P for trend=0.04) and lower risks of 26% for caffeinated coffee (P for trend<0.001), 16% for decaffeinated coffee (P for trend=0.01), 11% for tea (P for trend=0.02), 31%-33% for wine (P for trend<0.005), 41% for beer (P for trend<0.001), and 12% for orange juice (P for trend=0.004).
Consumption of sugar-sweetened soda and punch is associated with a higher risk of stone formation, whereas consumption of coffee, tea, beer, wine, and orange juice is associated with a lower risk.
Environmental factors have been associated with the outbreak of chronic kidney disease (CKD). We evaluated the association of Cadmium (Cd) exposure with the risk of CKD in U.S. adults who ...participated in the 1999-2006 National Health and Nutrition Examination Surveys (NHANES).
5426 subjects > or = 20 years were stratified for values of urinary and blood Cd and a multivariate logistic regression was performed to test the association between blood and urinary Cd, CKD and albuminuria (ALB) after adjustment for age, gender, race/ethnicity, body mass index and smoking habits.
Subjects with urinary Cd > 1 mcg/g and subjects with blood Cd > 1 mcg/L showed a higher association with ALB (OR 1.63, 95% CI 1.23, 2.16; P = 0.001). Subjects with blood Cd > 1 mcg/L showed a higher association with both CKD (OR 1.48, 95% CI 1.01, 2.17; P = 0.046) and ALB (OR 1.41, 95% CI 1.10, 1.82; P = 0.007). An interaction effect on ALB was found for high levels of urinary and blood Cd (P = 0.014).
Moderately high levels of urinary and blood Cd are associated with a higher proportion of CKD and ALB in the United States population.
CKD prevalence estimation is central to CKD management and prevention planning at the population level. This study estimated CKD prevalence in the European adult general population and investigated ...international variation in CKD prevalence by age, sex, and presence of diabetes, hypertension, and obesity. We collected data from 19 general-population studies from 13 European countries. CKD stages 1-5 was defined as eGFR<60 ml/min per 1.73 m(2), as calculated by the CKD-Epidemiology Collaboration equation, or albuminuria >30 mg/g, and CKD stages 3-5 was defined as eGFR<60 ml/min per 1.73 m(2) CKD prevalence was age- and sex-standardized to the population of the 27 Member States of the European Union (EU27). We found considerable differences in both CKD stages 1-5 and CKD stages 3-5 prevalence across European study populations. The adjusted CKD stages 1-5 prevalence varied between 3.31% (95% confidence interval 95% CI, 3.30% to 3.33%) in Norway and 17.3% (95% CI, 16.5% to 18.1%) in northeast Germany. The adjusted CKD stages 3-5 prevalence varied between 1.0% (95% CI, 0.7% to 1.3%) in central Italy and 5.9% (95% CI, 5.2% to 6.6%) in northeast Germany. The variation in CKD prevalence stratified by diabetes, hypertension, and obesity status followed the same pattern as the overall prevalence. In conclusion, this large-scale attempt to carefully characterize CKD prevalence in Europe identified substantial variation in CKD prevalence that appears to be due to factors other than the prevalence of diabetes, hypertension, and obesity.
Recent epidemiologic studies have provided evidence for an association between nephrolithiasis and cardiovascular disease, although the underlying mechanism is still unclear. Vascular calcification ...(VC) is a strong predictor of cardiovascular morbidity and the hypothesis explored in this study is that VC is more prevalent in calcium kidney stone formers (KSFs). The aims of this study were to determine (1) whether recurrent calcium KSFs have more VC and osteoporosis compared with controls and (2) whether hypercalciuria is related to VC in KSFs.
This is a retrospective, matched case-control study that included KSFs attending an outpatient nephrology clinic of the Royal Free Hospital (London, UK) from 2011 to 2014. Age- and sex-matched non-stone formers were drawn from a list of potential living kidney donors from the same hospital. A total of 111 patients were investigated, of which 57 were KSFs and 54 were healthy controls. Abdominal aortic calcification (AAC) and vertebral bone mineral density (BMD) were assessed using available computed tomography (CT) imaging. The prevalence, severity, and associations of AAC and CT BMD between KSFs and non-stone formers were compared.
Mean age was 47±14 years in KSFs and 47±13 in non-stone formers. Men represented 56% and 57% of KSFs and non-stone formers, respectively. The prevalence of AAC was similar in both groups (38% in KSFs versus 35% in controls, P=0.69). However, the AAC severity score (median 25th percentile, 75th percentile) was significantly higher in KSFs compared with the control group (0 0, 43 versus 0 0, 10, P<0.001). In addition, the average CT BMD was significantly lower in KSFs (159±53 versus 194 ±48 Hounsfield units, P<0.001). A multivariate model adjusted for age, sex, high BP, diabetes, smoking status, and eGFR confirmed that KSFs have higher AAC scores and lower CT BMD compared with non-stone formers (P<0.001 for both). Among stone formers, the association between AAC score and hypercalciuria was not statistically significant (P=0.86).
This study demonstrates that patients with calcium kidney stones suffer from significantly higher degrees of aortic calcification than age- and sex-matched non-stone formers, suggesting that VC may be an underlying mechanism explaining reported associations between nephrolithiasis and cardiovascular disease. Moreover, bone demineralization is more prominent in KSFs. However, more data are needed to confirm the possibility of potentially common underlying mechanisms leading to extraosseous calcium deposition and osteoporosis in KSFs.
Background
Nephrolithiasis is a frequent condition. While it is generally accepted that such condition carries a risk of recurrence over time, the exact risk and its predictors have been rarely ...quantitated. We aimed to estimate recurrence of kidney stones, overall and in specific subgroups, from randomized controlled trials (RCTs) of calcium stone formers.
Methods
Systematic review of RCTs of adult patients with idiopathic calcium kidney stones. Recurrence rates analyzed in subgroups based on type of intervention and other characteristics, using Poisson regression models.
Results
The analysis included 21 RCTs with 2168 participants over a median follow-up of 3.2 years (range 0.5–9.7). The median recurrence of kidney stones was 15 per 100 person–years (range 0–110). Recurrence was higher in those with two or more previous stone episodes compared to those with a single episode at enrolment (16 vs. 6 per 100 person–years, p < 0.001) and in those untreated or treated with dietary changes compared to those treated with drugs (26 vs. 23 vs. 9 per 100 person–years, p < 0.001). The effect of drugs on recurrence seemed to be beneficial only among those with two or more previous stone episodes.
Conclusions
The overall recurrence rate of stones depends on factors such as previous stone history and type of treatment. Dietary approaches seem to be more effective among single stone formers, whereas drugs seem to be more effective among recurrent stone formers.
Kidney stone disease is a multifactorial condition influenced by both genetic predisposition and environmental factors such as lifestyle and dietary habits. Although different monogenic polymorphisms ...have been proposed as playing a causal role for calcium nephrolithiasis, the prevalence of these mutations in the general population and their complete pathogenetic pathway is yet to be determined. General dietary advice for kidney stone formers includes elevated fluid intake, dietary restriction of sodium and animal proteins, avoidance of a low calcium diet, maintenance of a normal body mass index, and elevated intake of vegetables and fibers. Thus, balanced calcium consumption protects against the risk for kidney stones by reducing intestinal oxalate availability and its urinary excretion. However, calcium supplementation given between meals might increase urinary calcium excretion without the beneficial effect on oxalate. In kidney stone formers, circulating active vitamin D has been found to be increased, whereas higher plasma 25-hydroxycholecalciferol seems to be present only in hypercalciuric patients. The association between nutritional vitamin D supplements and the risk for stone formation is currently not completely understood. However, taken together, available evidence might suggest that vitamin D administration worsens the risk for stone formation in patients predisposed to hypercalciuria. In this review, we analyzed and discussed available literature on the effect of calcium and vitamin D supplementation on the risk for kidney stone formation.
Background Previous studies of vitamin C and kidney stones were conducted mostly in men and either reported disparate results for supplemental and dietary vitamin C or did not examine dietary vitamin ...C. Study Design Prospective cohort analysis. Setting & Participants 156,735 women in the Nurses’ Health Study (NHS) I and II and 40,536 men in the Health Professionals Follow-up Study (HPFS). Predictor Total, dietary, and supplemental vitamin C intake, adjusted for age, body mass index, thiazide use, and dietary factors. Outcomes Incident kidney stones. Results During a median follow-up of 11.3 to 11.7 years, 6,245 incident kidney stones were identified. After multivariable adjustment, total vitamin C intake (<90 reference, 90-249, 250-499, 500-999, and ≥1,000 mg/d) was not significantly associated with risk for kidney stones among women, but was among men (HRs of 1.00 reference, 1.19 95% CI, 0.99-1.46, 1.15 95% CI, 0.93-1.42, 1.29 95% CI, 1.04-1.60, and 1.43 95% CI, 1.15-1.79, respectively; P for trend = 0.005). Median total vitamin C intake for the 500- to 999-mg/d category was ∼700 mg/d. Supplemental vitamin C intake (no use reference, <500, 500-999, and ≥1,000 mg/d) was not significantly associated with risk for kidney stones among women, but was among men (HR, 1.19 95% CI, 1.01-1.40 for ≥1,000 mg/d; P for trend = 0.001). Dietary vitamin C intake was not associated with stones among men or women, although few participants had dietary intakes > 700 mg/d. Limitations Nutrient intakes derived from food-frequency questionnaires, lack of data on stone composition for all cases. Conclusions Total and supplemental vitamin C intake was significantly associated with higher risk for incident kidney stones in men, but not in women.
Kidney stone disease is common and may be associated with an increased risk of coronary heart disease (CHD). Previous studies of the association between kidney stones and CHD have often not ...controlled for important risk factors, and the results have been inconsistent.
To examine the association between a history of kidney stones and the risk of CHD in 3 large prospective cohorts.
A prospective study of 45,748 men and 196,357 women in the United States without a history of CHD at baseline who were participants in the Health Professionals Follow-up Study (HPFS) (45,748 men aged 40-75 years; follow-up from 1986 to 2010), Nurses' Health Study I (NHS I) (90,235 women aged 30-55 years; follow-up from 1992 to 2010), and Nurses' Health Study II (NHS II) (106,122 women aged 25-42 years; follow-up from 1991 to 2009). The diagnoses of kidney stones and CHD were updated biennially during follow-up.
Coronary heart disease was defined as fatal or nonfatal myocardial infarction (MI) or coronary revascularization. The outcome was identified by biennial questionnaires and confirmed through review of medical records. RESULTS Of a total of 242,105 participants, 19,678 reported a history of kidney stones. After up to 24 years of follow-up in men and 18 years in women, 16,838 incident cases of CHD occurred. After adjusting for potential confounders, among women, those with a reported history of kidney stones had an increased risk of CHD than those without a history of kidney stones in NHS I (incidence rate IR, 754 vs 514 per 100,000 person-years; multivariable hazard ratio HR, 1.18 95% CI, 1.08-1.28) and NHS II (IR, 144 vs 55 per 100,000 person-years; multivariable HR, 1.48 95% CI, 1.23-1.78). There was no significant association in men (IR, 1355 vs 1022 per 100,000 person-years; multivariable HR, 1.06 95% CI, 0.99-1.13). Similar results were found when analyzing the individual end points (fatal and nonfatal MI and revascularization).
Among the 2 cohorts of women, a history of kidney stones was associated with a modest but statistically significantly increased risk of CHD; there was no significant association in a separate cohort of men. Further research is needed to determine whether the association is sex-specific.
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