Dietary Magnesium Intake and Kidney Stone: The National Health and Nutrition Examination Survey 2011-2018.

BACKGROUND: The association between dietary magnesium intake (DMI) and kidney stone (KS) disease is not clear. AIM: To determine the association between DMI and prevalent KS disease defined as self-report of any previous episode of KS. METHODS: We examined The National Health and Nutrition Examination Survey (NHANES) 2011-2018 and used logistic regression analyses adjusting for demographics, BMI, histories of hypertension, diabetes, thiazide use, cigarette smoking, alcohol drinking, relevant dietary and supplemental intakes to determine the independent association between DMI and prevalent KS disease. RESULTS: A total of 19,271 participants were eligible for the final analysis, including 1878 prevalent KS formers. Mean DMI among stone formers was 295.4 mg/day, as compared to 309.6 mg/day among non-stone formers (p=0.02). Higher DMI was strongly associated with lower odds of prevalent KS disease in univariate analysis regardless of when DMI was analyzed as a continuous variable (OR=0.94, 95% CI: 0.89-0.99, p=0.02) or when the extreme quartiles of DMI were compared (OR=0.74, 95% CI: 0.60-0.92, p=0.007). In the multivariable-adjusted regression analysis, those in the highest quartile of DMI compared to the lowest quartile (≥379 mg vs. <205 mg) had significantly reduced odds of prevalent KS (OR=0.70, 95% CI: 0.52-0.93, p=0.01). When DMI was analyzed as a continuous variable, there was a trend toward reduced odds of prevalent KS disease with higher DMI (OR=0.92 per 100 mg, 95% CI: 0.84-1.01, p=0.07). CONCLUSIONS: Our study suggests that higher DMI is associated with a reduced risk of KS disease. Future prospective studies are needed to clarify the causal relationship between DMI and KS disease.

Risk factors for the comorbidity of osteoporosis/osteopenia and kidney stones: a cross-sectional study.

Low femoral neck bone mineral density (BMD) was associated with the increased risk of kidney stones. Low dietary magnesium intake and increased serum alkaline phosphatase were associated with the increased risk of low femoral neck BMD in kidney stone formers. PURPOSE: To evaluate whether low femoral neck bone mineral density (BMD) was associated with a higher risk of kidney stones, and identify risk factors for the comorbidity of osteoporosis/osteopenia and kidney stones. METHODS: We analyzed individuals aged ≥ 20 years from National Health and Nutrition Examination Survey 2007-2020 data. Osteoporosis/osteopenia is defined as any T-score < -1.0 of femoral neck, total femoral, and mean lumbar spine (L1-L4) BMD. Dietary intakes (sodium, potassium, magnesium, calcium, phosphorus, calcium/phosphorus, vitamin D (25OHD2+25OHD3)) and serum parameters (sodium, potassium, calcium, phosphorus, bicarbonate, vitamin D, alkaline phosphatase (ALP)) were screened for identifying risk factors for the comorbidity. RESULTS: The prevalence of comorbidity of osteoporosis/osteopenia and kidney stones was 4.82%. Femoral neck BMD T-score was negatively associated with the prevalence of kidney stones (n=11,864). Dietary magnesium intake, serum phosphorus, and bicarbonate were negatively associated with the comorbidity prevalence, and serum ALP was positively associated with the comorbidity prevalence (n=6978). Additionally, there remain significant associations of dietary magnesium intake, serum ALP, and bicarbonate with not only femoral neck BMD T-score (n=11331), but also the prevalence of kidney stones (n=23,111) in general population. Furthermore, dietary magnesium intake was positively correlated to femoral neck BMD T-score in stone formers (SFs), while serum ALP was negatively correlated to femoral neck BMD T-score in SFs (n=1163). CONCLUSION: Low femoral neck BMD was closely associated with an increased risk of kidney stones. Low magnesium intake and increased serum ALP were associated with the increased risk of the comorbidity, as well as indicative of low femoral neck BMD T-score in SFs, which offered a clue to further clarify the mechanism leading to paradoxical calcification of bone resorption and kidney stones, and had the potential to perform personalized diagnostic workup for low BMD in SFs.

Relationship between Serum Selenium Level and Self-Reported History of Kidney Stone.

A relationship may exist between selenium and kidney calculi, but there is a lack of research in this field at present. Our study explored the relationship between the serum selenium level and a medical history of adult kidney calculi. We utilized data from the National Health and Nutrition Examination Survey conducted between 2011 and 2016. Participants self-reported their history of kidney stones, while serum selenium levels were measured using inductively coupled plasma dynamic reaction cell mass spectrometry. Our findings indicate a negative correlation between serum selenium levels and the risk of kidney stone history. In the multiple-adjusted model, the lowest serum selenium level group had a higher risk than the other groups. The odds ratio (95% confidence interval) of ever having kidney stones for the highest serum selenium level group was 0.54 (0.33-0.88). In the results of stratified analysis, this relationship was still significant in the groups of women and those 40-59 years. We also found that as a nonlinear dose-response relationship between serum selenium levels and the history of kidney stones disease. In our research, we found that people with higher serum selenium levels had a lower risk of having a history of kidney stones. We concluded that selenium may have a protective effect on kidney stones. In the future, more population studies are needed to explore the relationship between selenium and kidney stones.

Why is childhood urolithiasis increasing? Etiology, diagnosis and management: a single-center experience.

BACKGROUND: Globally, urolithiasis is becoming more and more common among children. We aimed to determine the etiology, and the diagnostic and therapeutic approaches in patients with urolithiasis. METHODS: This was a retrospective study which included all patients (aged 1 month-18 years) admitted to the pediatric nephrology clinic in Elazig Fethi Sekin City Hospital with urolithiasis between November 2019 and 2021. Only patients whose diagnosis of urolithiasis was confirmed by urinary ultrasonography were included in the study, while patients with chronic diseases (neurological diseases such as epilepsy, cerebral palsy, chronic bowel diseases, etc.) predisposing to kidney stone formation were not. Demographic characteristics, serum and urine biochemical parameters, urine metabolic and kidney stone metabolic and chemical analyses, urinary tract ultrasonography findings and treatment modalities were collected. RESULTS: One hundred ninety-seven patients (91 female and 106 male) were included in the study. Hypervitaminosis D was detected in 4 (2%) patients, suppressed parathyroid hormone in 12 (6%) and hypercalcemia in 27 (14%) patients. Metabolic screening showed hypercalciuria in 69 (35%) patients, hypocitraturia in 39 (20%), hyperoxaluria in 15 (8%) and cystinuria in 6 (3%) patients. Eighty three (42%) patients had a positive family history for kidney stones. One hundred eighteen (60%) patients received potassium citrate treatment, 71 (36%) were given hydration and diet recommendations without medical treatment, 6 (3%) received tiopronin treatment, and 2 (1%) patients were treated surgically. CONCLUSIONS: Our study suggests that Vitamin D supplementation at doses higher than 400 IU/day may be a risk factor for kidney stones in children. We observed that mothers tend not to give water to infants who are breastfed or formula-fed in the first year of life. K-citrate treatment can be a good option for prevention and dissolution of stones by alkalinization.

Differences in the Food Consumption Between Kidney Stone Formers and Nonformers in the Swiss Kidney Stone Cohort.

OBJECTIVE: Diet has a major influence on the formation and management of kidney stones. However, kidney stone formers' diet is difficult to capture in a large population. Our objective was to describe the dietary intake of kidney stone formers in Switzerland and to compare it to nonstone formers. METHODS: We used data from the Swiss Kidney Stone Cohort (n = 261), a multicentric cohort of recurrent or incident kidney stone formers with additional risk factors, and a control group of computed tomography-scan proven nonstone formers (n = 197). Dieticians conducted two consecutive 24-h dietary recalls, using structured interviews and validated software (GloboDiet). We took the mean consumption per participant of the two 24-h dietary recalls to describe the dietary intake and used two-part models to compare the two groups. RESULTS: The dietary intake was overall similar between stone and nonstone formers. However, we identified that kidney stone formers had a higher probability of consuming cakes and biscuits (odds ratio (OR) [95% CI] = 1.56[1.03; 2.37]) and soft drinks (OR = 1.66[1.08; 2.55]). Kidney stone formers had a lower probability of consuming nuts and seeds (OR = 0.53[0.35; 0.82]), fresh cheese (OR = 0.54[0.30; 0.96]), teas (OR = 0.50[0.3; 0.84]), and alcoholic beverages (OR = 0.35[0.23; 0.54]), especially wine (OR = 0.42[0.27; 0.65]). Furthermore, among consumers, stone formers reported smaller quantities of vegetables (ß coeff[95% CI] = - 0.23[- 0.41; - 0.06]), coffee (ß coeff = - 0.21[- 0.37; - 0.05]), teas (ß coeff = - 0.52[- 0.92; - 0.11]) and alcoholic beverages (ß coeff = - 0.34[- 0.63; - 0.06]). CONCLUSION: Stone formers reported lower intakes of vegetables, tea, coffee, and alcoholic beverages, more specifically wine, but reported drinking more frequently soft drinks than nonstone formers. For the other food groups, stone formers and nonformers reported similar dietary intakes. Further research is needed to better understand the links between diet and kidney stone formation and develop dietary recommendations adapted to the local settings and cultural habits.

Dietary Selenium Intake and Kidney Stones in Old Adults: an Analysis from NHANES 2011 to 2018.

The association between dietary selenium intake and kidney stones remains unclear. The purpose of this study was to explore the correlation between dietary selenium intake and kidney stones in older adults. A total of 6669 adults aged ≥ 60 years who had participated in the National Health and Nutrition Examination Survey (NHANES) during 2011-2018 were enrolled in the current study. The correlation between dietary selenium intake and kidney stones was assessed by the logistic regression analysis. Smooth curve fitting was used to explore the potential non-linear relationship and subgroup analyses were further adopted. After adjustment for multiple confounding factors, the odds ratio (OR) with 95% confidence interval (CI) of kidney stones for per standard deviation increment in dietary selenium intake was 0.92 (0.85, 1.00) overall. Compared with the lowest quartile, the ORs (95% CIs) with increasing quartiles were 0.88 (0.71, 1.08), 0.82 (0.66, 1.02), and 0.79 (0.64, 0.97). In addition, smooth curve fitting and stratified analyses showed that there was a non-linear and stable correlation between dietary selenium intake and the occurrence of kidney stones respectively. For adults aged over 60, dietary selenium intake was inversely correlated with kidney stones, and this relationship remained after adjusting for other confounding variables. Further researches are needed to explore the potential mechanism between dietary selenium intake and kidney stones.

Dietary Risk Factors for Incident and Recurrent Symptomatic Kidney Stones.

OBJECTIVE: To compare dietary factors between incident symptomatic stone formers and controls, and among the incident stone formers, to determine whether dietary factors were predictive of symptomatic recurrence. PATIENTS AND METHODS: We prospectively recruited 411 local incident symptomatic kidney stone formers (medical record validated) and 384 controls who were seen at Mayo Clinic in Minnesota or Florida between January 1, 2009, and August 31, 2018. Dietary factors were based on a Viocare, Inc, food frequency questionnaire administered during a baseline in-person study visit. Logistic regression compared dietary risk factors between incident symptomatic stone formers and controls. Incident stone formers were followed up for validated symptomatic recurrence in the medical record. Cox proportional hazards models estimated risk of symptomatic recurrence with dietary factors. Analyses adjusted for fluid intake, energy intake, and nondietary risk factors. RESULTS: In fully adjusted analyses, lower dietary calcium, potassium, caffeine, phytate, and fluid intake were all associated with a higher odds of an incident symptomatic kidney stone. Among incident stone formers, 73 experienced symptomatic recurrence during a median 4.1 years of follow-up. Adjusting for body mass index, fluid intake, and energy intake, lower dietary calcium and lower potassium intake were predictive of symptomatic kidney stone recurrence. With further adjustment for nondietary risk factors, lower dietary calcium intake remained a predictor of recurrence, but lower potassium intake only remained a predictor of recurrence among those not taking thiazide diuretics or calcium supplements. CONCLUSION: Enriching diets in stone formers with foods high in calcium and potassium may help prevent recurrent symptomatic kidney stones.

Evaluating perceptions and usage of natural remedies, herbal medicine, and dietary supplements for kidney stones among a diverse, international, urban patient population.

Our goal was to assess the use and perceptions of complementary and alternative medicine (CAM) for kidney stones among a diverse, urban population. This was a cross-sectional study of patients treated for kidney stones in the Bronx, NY. We assessed demographic information, personal history of kidney stones, as well as knowledge and use of CAM for kidney stones. Patient demographics and responses were analyzed using chi-squared, t tests, and binomial logistic regression. 113 patients were surveyed. 90% identified as non-white, of whom 58% indicated Hispanic, 46% Latinx, and 23% Black. 56% of patients were born outside the United States. 56% of patients had heard of CAM for kidney stones and 44% had used CAM for kidney stones. The most common CAM were fruits (N = 42, 84%). Recurrent stone formers were more likely than first-time stone formers to have heard of CAM (68 vs 44% p = 0.013) and to have used CAM (56 vs 30%, p = 0.008). Those identifying as Hispanic were more likely to have both heard of and tried CAM for kidney stones (p = 0.036 and 0.022, respectively) compared to non-Hispanic patients. CAM are commonly used among our diverse, urban patient population. While some remedies are high in citrate and alkali (i.e., lemon, cranberry), others are high in oxalate (i.e., beets) and could potentially contribute to stone formation. These findings underpin the importance that medical providers educate themselves on the CAM used in their specific patient populations and discussing use with patients. Providers should aim to identify and reconcile therapeutics that oppose goals of treatment.

Kidney Stone Events Following Parathyroidectomy vs Nonoperative Management for Primary Hyperparathyroidism.

CONTEXT: Primary hyperparathyroidism (PHPT) is associated with an increased risk of kidney stones. Few studies account for PHPT severity or stone risk when comparing stone events after parathyroidectomy vs nonoperative management. OBJECTIVE: Compare the incidence of kidney stone events in PHPT patients treated with parathyroidectomy vs nonoperative management. DESIGN: Longitudinal cohort study with propensity score inverse probability weighting and multivariable Cox proportional hazards regression. SETTING: Veterans Health Administration integrated health care system. PATIENTS: A total of 44 978 patients with > 2 years follow-up after PHPT diagnosis (2000-2018); 5244 patients (11.7%) were treated with parathyroidectomy. MAIN OUTCOMES MEASURE: Clinically significant kidney stone event. RESULTS: The cohort had a mean age of 66.0 years, was 87.8% male, and 66.4% White. Patients treated with parathyroidectomy had higher mean serum calcium (11.2 vs 10.8mg/dL) and were more likely to have a history of kidney stone events. Among patients with baseline history of kidney stones, the unadjusted incidence of ≥ 1 kidney stone event was 30.5% in patients managed with parathyroidectomy (mean follow-up, 5.6 years) compared with 18.0% in those managed nonoperatively (mean follow-up, 5.0 years). Patients treated with parathyroidectomy had a higher adjusted hazard of recurrent kidney stone events (hazard ratio [HR], 1.98; 95% CI, 1.56-2.51); however, this association declined over time (parathyroidectomy × time: HR, 0.80; 95% CI, 0.73-0.87). CONCLUSION: In this predominantly male cohort with PHPT, patients treated with parathyroidectomy continued to be at higher risk of kidney stone events in the immediate years after treatment than patients managed nonoperatively, although the adjusted risk of stone events declined with time, suggesting a benefit to surgical treatment.

Coffee and Caffeine Consumption and Risk of Kidney Stones: A Mendelian Randomization Study.

RATIONALE & OBJECTIVE: Coffee and caffeine consumption have been associated with a lower risk of kidney stones in observational studies. We conducted a Mendelian randomization study to assess the causal nature of these associations. STUDY DESIGN: Mendelian randomization analysis. SETTING & PARTICIPANTS: Independent genetic variants associated with coffee and caffeine consumption at the genome-wide significance level were selected from previously published meta-analyses as instrumental variables. Summary-level data for kidney stones were obtained from the UK Biobank study (6,536 cases and 388,508 noncases) and the FinnGen consortium (3,856 cases and 172,757 noncases). EXPOSURE: Genetically predicted coffee and caffeine consumption. OUTCOME: Clinically diagnosed kidney stones. ANALYTICAL APPROACH: Mendelian randomization methods were used to calculate causal estimates. Estimates from the 2 sources were combined using the fixed-effects meta-analysis methods. RESULTS: Genetically predicted coffee and caffeine consumption was associated with a lower risk of kidney stones in the UK Biobank study, and the associations were directionally similar in the FinnGen consortium. The combined odds ratio of kidney stones was 0.60 (95% CI, 0.46-0.79; P < 0.001) per a genetically predicted 50% increase in coffee consumption and 0.81 (95% CI, 0.69-0.94; P = 0.005) per a genetically predicted 80-mg increase in caffeine consumption. LIMITATIONS: Genetic influence on kidney stone risk via pathways not involving coffee or caffeine. CONCLUSIONS: Using genetic data, this study provides evidence that higher coffee and caffeine consumption may cause a reduction in kidney stones.

Temporal Trends of Dietary Risk Factors after a Diagnosis of Kidney Stones.

BACKGROUND AND OBJECTIVES: Diet is an important contributor to kidney stone formation, but there are limited data regarding long-term changes in dietary factors after a kidney stone. DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS: We analyzed data from three longitudinal cohorts, the Health Professionals Follow-Up Study and Nurses' Health Study I and II, comparing changes in dietary factors in participants with and without kidney stones during follow-up. The daily intake of dietary calcium, supplemental calcium, animal protein, caffeine, fructose, potassium, sodium, oxalate, phytate, vitamin D, vitamin C, sugar-sweetened beverages, fluids, net endogenous acid production, and Dietary Approaches to Stop Hypertension score were assessed by repeat food frequency questionnaires and computed as absolute differences; a difference-in-differences approach was used to account for temporal changes using data from participants without kidney stones from the same calendar period. RESULTS: Included were 184,398 participants with no history of kidney stones, 7095 of whom became confirmed stone formers. Several intakes changed significantly over time in stone formers, with some showing a relative increase up to 8 years later, including caffeine (difference in differences, 8.8 mg/d; 95% confidence interval [95% CI], 3.4 to 14.1), potassium (23.4 mg/d; 95% CI, 4.6 to 42.3), phytate (12.1 mg/d; 95% CI, 2.5 to 21.7), sodium (43.1 mg/d; 95% CI, 19.8 to 66.5), and fluids (47.1 ml/d; 95% CI, 22.7 to 71.5). Other dietary factors showed a significant decrease, such as oxalate (-7.3 mg/d; 95% CI, -11.4 to -3.2), vitamin C (-34.2 mg/d; 95% CI, -48.8 to -19.6), and vitamin D (-18.0 IU/d; 95% CI, -27.9 to -8.0). A significant reduction was observed in sugar-sweetened beverages intake of -0.5 (95% CI, -0.8 to -0.3) and -1.4 (95% CI, -1.8 to -1.0) servings per week and supplemental calcium of -105.1 (95% CI, -135.4 to -74.7) and -69.4 (95% CI, -95.4 to -43.4) mg/d for women from Nurses' Health Study I and II, respectively. Animal protein, dietary calcium, fructose intake, Dietary Approaches to Stop Hypertension score, and net endogenous acid production did not change significantly over time. CONCLUSIONS: After the first episode of a kidney stone, mild and inconsistent changes were observed concerning dietary factors associated with kidney stone formation.

The Associations Between Tea and Coffee Drinking and Risk of Calcium-Oxalate Renal Stones.

Findings regarding the association between tea and coffee consumption and oxalate-calcium stone are sparse and uncertain. The purpose of this study was to investigate the relations of tea and coffee with the risk of calcium oxalate stone formation. A total sample of 215 newly diagnosed patients with calcium oxalate stones and 215 controls matched for sex and age were recruited. Dietary intake of participants was assessed using a validated food frequency questionnaire over the preceding year and participants were asked to determine how many glasses of tea and cups of coffee they usually use. The associations between tea and coffee and kidney stone were examined using multivariable logistic regression. Compared with controls, cases had greater intake of tea (2.18±0.76 vs. 1.82±0.79 glasses/d) but lower intake of coffee (1.18±0.38 vs. 1.26±0.44 cups/week). After adjustment for potential confounders, compared with those who drank <2 glasses of tea/d, individuals with tea consumption of ≥4 glasses/d had greater risk for having calcium oxalate stone (OR= 2.73; 95 % CI: 1.50, 4.99). In the crude model, compared with coffee consumption for <1 cup/week, consumption of ≥1 cup/week was associated with a 38 % decrease in the risk of calcium oxalate stone. However, adjustment for potential confounders disappeared the significance (OR=0.81; 95 % CI: 0.48, 1.35). These results suggest that while high consumption of tea is associated with increased risk of calcium oxalate kidney stone, coffee drinking is not pertinent. However, due to low consumption of coffee in this population, our results should be interpreted cautiously.

Consumption of Tea, Alcohol, and Fruits and Risk of Kidney Stones: A Prospective Cohort Study in 0.5 Million Chinese Adults.

A few prospective studies have suggested that tea, alcohol, and fruit consumption may reduce the risk of kidney stones. However, little is known whether such associations and their combined effect persist in Chinese adults, for whom the popular tea and alcohol drinks are different from those investigated in the aforementioned studies. The present study included 502,621 participants from the China Kadoorie Biobank (CKB). Information about tea, alcohol, and fruit consumption was self-reported at baseline. The first documented cases of kidney stones during follow-up were collected through linkage with the national health insurance system. Cox regression was used to calculate the hazard ratio (HR) and 95% confidence interval (CI). During a median of 11.1 years of follow-up, we collected 12,407 cases of kidney stones. After multivariable adjustment, tea, alcohol, and fruit consumption were found to be negatively associated with kidney stone risk, but the linear trend was only found in tea and fruit consumption. Compared with non-tea consumers, the HR (95% CI) for participants who drank ≥7 cups of tea per day was 0.73 (0.65-0.83). Compared with non-alcohol consumers, the HR (95% CI) was 0.79 (0.72-0.87) for participants who drank pure alcohol of 30.0-59.9 g per day but had no further decrease with a higher intake of alcohol. Compared with less-than-weekly consumers, the HR (95% CI) for daily fruit consumers was 0.81 (0.75-0.87). Even for those who did not drink alcohol excessively, increasing tea and fruit consumption could also independently reduce the stone risk. Among Chinese adults, tea, alcohol, and fruit consumption was associated with a lower risk of kidney stones.

Klotho gene polymorphism in renal stone formers from Northwestern India.

Klotho gene is an important gene involved in calcium homeostasis, and polymorphisms of this gene may render the individual prone to renal stone formation. We evaluated G395A single nucleotide polymorphisms (SNPs) of Klotho gene at rs1207568 in renal stone patients of North India. This was a prospective study involving 150 patients of renal stone disease (aged 15-60 years) and 100 age- and sex-matched controls. The DNA was isolated and subjected to polymerase chain reaction (PCR) for identifying the G395A Klotho SNPs at rs1207568. Confronting two pair primers were used, and gel electrophoresis showing two bands at 175,252 bp was considered as GG genotype, three bands at 121,175 and 252 bp as GA and two bands at 121 and 252 bp as AA genotype. The association between genotype and cases was evaluated by using Chi-square test and logistic regression analysis. Cases and controls were well matched for age (40.65 vs 42.06, p = 0.063) and sex (p = 0.420). Significantly high proportion of patients with renal stones had GG genotype as compared to controls (odds ratio (OR) 2.37(1.39,4.03), p = 0.001). None of the participants (cases and controls) had homozygous recessive AA genotype. The risk of stone formation was significantly higher in the population carrying G allele {OR 1.94 (1.225-3.073), p 0.004}. Mean serum calcium was higher in stone formers with GG genotype as compared to those with GA genotype (9.16 mg/dl vs 8.91 mg/dl; p = 0.06). GG genotype of G396A Klotho gene SNPs is associated with renal stone formation. The G allele carrier is twice at risk of renal stone formation. The absence of AA genotype in north-western Indian population remains a curiosity.

Nutrients, vitamins, probiotics and herbal products: an update of their role in urolithogenesis.

Nutrients, vitamins, probiotics, and herbal products may be risk factors, or alternately, protect against the formation of urinary stones. The purpose of this review was to update knowledge of the role of nutraceuticals in renal stone formation. A systematic search of the relevant literature published in PubMed in the last ten years was conducted and a narrative review of the data from the included studies was done. Search screened 513 studies that were reduced to 34 after evaluation by title and abstract; other 38 studies were retrieved by references of the selected studies. Beverages high fluid intake confirmed protective effect; orange juice protective effect; apple or grapefruit juice not confirmed as risk factors; sugar-sweetened soda and punch increased risk of stone formation. Energy intake: very high energy intake increased risk factor for women (especially after menopause); dietary acid load increased risk at equal levels of energy intake. Macronutrients confirmed increased risk of high protein intake. Calcium and Oxalate: calcium intake protective effect; oxalate intake only modest increase of risk in men and older women. Metal cations zinc and iron intake no clear impact on the risk of stone formation, dietary copper increased risk; manganese intake reduced risk of stone formation. Fruits and Vegetables decreased risk. Vitamins B6 intake not associated to risk of stone formation; vitamin C intake increased risk in men; vitamin D or supplemental vitamin D intake not associated to increased risk in men and younger women, suggestion of a higher risk in older women; Probiotics Gut colonization with Oxalobacter formigenes associated to lower risk of stone formation, effect of oxalate-degraders probiotics on urinary oxalate equivocal. Herbal products efficacy of some herbal products demonstrated in some trials, more investigations needed to confirm their efficacy and safety.

Exploring the Potential Relationship Between Phytate Ingestion, Urinary Phytate Excretion, and Renal Stone Risk in a Unique Human Model: No Hard Evidence in Support of Phytate as a Stone Inhibitor.

OBJECTIVE: Dietary phytate (IP6) enjoys a reputation as an inhibitor of calcium renal stone formation, although there are very few human studies to support this notion. In South Africa, urolithiasis occurs in the white (W) but is rare in the black (B) population. We undertook this unique human model to further investigate the IP6 theory. METHODS: Healthy W and B males completed baseline food-frequency recall questionnaires. Dietary intake of IP6 was restricted for 18 days. An IP6 dietary supplement was ingested on days 15-18. Twenty-four-hour urinary phytate and other urinary components were determined. Relative supersaturations of calcium salts were calculated. The urinary metastable limit (MSL) of calcium oxalate (CaOx) and its crystallisation kinetics were determined experimentally. RESULTS: Habitual dietary intake of IP6 and its urinary excretion were significantly higher in B than in W (1650 ± 202 vs. 640 ± 134 mg/d, P = .0002 and 1.13 ± 0.12 vs. 0.75 ± 0.13 µM, P <.05, respectively). In B, urinary phytate decreased significantly after 15 days of IP6 restriction, but in W, its excretion remained constant. After supplementation, urinary IP6 increased significantly in both groups reaching levels commensurate with the baseline value in B. No significant differences occurred in B in any of the routine urinary risk factors throughout the trial. However, in W, urinary citrate excretion increased on day 18 relative to day 0. There were no significant intragroup or intergroup changes in relative supersaturation, metastable limit, or crystallization kinetics. CONCLUSIONS: Despite notable differences in the renal handling of ingested IP6, there were no changes in any of the well-established urinary risk factors for calcium renal stone formation in either of our uniquely different test groups. We conclude that, in the absence of hard evidence, claims that IP6 is a stone inhibitor remain unproven.

Caffeine intake and the risk of recurrent kidney stones in adults, an analysis of 2007-2014 National Health and Nutrition Examination Surveys.

PURPOSE: The association between caffeine intake and the risk of recurrent kidney stones is unknown. We examined the association between caffeine intake and the risk of recurrent kidney stones in adults. METHODS: Individuals with history of passing at least one kidney stone were included from 2007 to 2014 National Health and Nutrition Examination Survey. Recurrent kidney stones were defined using a standard questionnaire and structured dietary recalls were used to determine caffeine intake. The weighted logistic regression was used to assess the association between caffeine intake and the risk of recurrent kidney stones, and the non-linear relationship was explored with restricted cubic splines. Caffeine and dietary confounders (minerals and vitamins) were adjusted for total energy intake with residual model. RESULTS: The multivariate-adjusted odds ratios (95% confidence intervals) of recurrent kidney stones for per-quartile increment in caffeine intake were 1.15 (1.01-1.31) overall, 1.11 (0.96-1.29) for white race individuals, 1.33 (1.09-1.63) for non-white race individuals, 1.15 (0.97-1.36) for men, 1.24 (1.01-1.53) for women, 1.54 (1.08-2.19) for non-overweight individuals, 1.11 (0.97-1.28) for overweight/obese individuals, 1.13 (0.99-1.29) for caffeine from coffee, and 0.90 (0.79-1.03) for caffeine from non-coffee sources. A linear relationship was found between caffeine intake and the risk of recurrent kidney stones overall and in subgroup analyses. CONCLUSION: Compared with those who reported passing only one kidney stone, caffeine intake was independently and linearly associated with a higher risk of recurrent kidney stones in adults, especially for women, individuals of non-white race and non-overweight subjects. The increased risk may arise from caffeine from coffee.

Alkalinizing Agents: A Review of Prescription, Over-the-Counter, and Medical Food Supplements.

Introduction: Kidney stones affect 1 in every 11 people in the United States each year. There is a significant high recurrence rate without a stone prevention protocol. Alkali citrate is beneficial in decreasing stone recurrence, but because of the cost and gastrointestinal side effects there is a low adherence rate. This study aims to serve as a review of some of the most commonly used alkalizing over-the-counter supplements that are advertised to prevent and treat kidney stones. Methods: Data were gathered by a comprehensive online literature search and company inquiries for kidney stone prevention supplements. An additional informal poll of the authors selected supplements that are most commonly taken by their patients. A total of eight supplements were evaluated for cost, alkali equivalent provided, dosing, and regulatory information. Results: Eight of the most commonly used supplements were reviewed with a focus on alkalizing agents. Information reviewed revealed dosing recommendations resulting in decreased citrate alkali equivalents per day compared with prescription-strength potassium citrate. Cost, peer-reviewed study results, and regulatory data were reviewed, tabulated, and analyzed. Cost per alkali equivalent was substantially decreased for each supplement compared with the prescribed drug. All supplements were found to be readily available online. Conclusion: Over-the-counter alkalizing agents are available to patients and may be an appropriate alternative to cost-prohibitive potassium citrate when treating urolithiasis patients. Additional testing will be necessary in the future to determine the efficacy of these supplements in the treatment and prevention of urinary stone disease.

Feasibility of a Telemedicine-Administered, Pharmacist-Staffed, Protocol-Driven, Multicenter Program for Kidney Stone Prevention in a Large Integrated Health Care System: Results of a Pilot Program.

INTRODUCTION: Despite guidelines for prevention of recurrent renal calculi, routine dietary modification and metabolic evaluation are often not performed. OBJECTIVE: To determine feasibility of a multicenter, pharmacist-staffed program to enroll patients at high risk of recurrent kidney stones and provide dietary instruction, metabolic evaluation, and medical therapy via telemedicine. METHODS: A total of 536 consecutive adult patients were referred from 3 Northern California Kaiser Permanente facilities. We determined the proportion of patients who enrolled, received dietary counseling, and completed metabolic evaluation at 12 months. The program was staffed by a clinical pharmacist and supervised by urologists following a protocol based on the American Urological Association guidelines. Patients were contacted entirely via telemedicine. Cystine or struvite kidney stones, renal tubular acidosis, and primary hyperoxaluria were exclusion criteria. RESULTS: Of the 536 patients, 500 agreed to enrollment. Among patients enrolled for 3 months, 99% self-reported compliance with at least 3 of 5 aspects of dietary advice. A complete metabolic evaluation including 24-hour urine collection was performed in 80% of patients by 12 months. A significant improvement in all urinary parameters occurred in 52 patients with calcium stones who repeated 24-hour urine testing. The 12-month dropout rate was 12.4%. CONCLUSION: A telemedicine-administered, pharmacist-staffed, protocol-driven program can provide dietary advice and obtain compliance with metabolic testing for patients at high risk of recurrent kidney stones. Rates of metabolic testing and dropout compare favorably with previously reported rates. This report represents, to our knowledge, the first telemedicine-administered, pharmacist-staffed, kidney stone prevention program published in the literature.