Recurrent Kidney Stone Formers Research Articles

Serum sclerostin is associated with recurrent kidney stone formation independent of hypercalciuria.

Kidney stones are frequent in industrialized countries with a lifetime risk of 10 to 15%. A high percentage of individuals experience recurrence. Calcium-containing stones account for more than 80% of kidney stones. Diet, environmental factors, behavior, and genetic variants contribute to the development of kidney stones. Osteocytes excrete the 21kDa glycoprotein sclerostin, which inhibits bone formation by osteoblasts. Animal data suggests that sclerostin might directly or indirectly regulate calcium excretion via the kidney. As hypercalciuria is one of the most relevant risk factors for kidney stones, sclerostin might possess pathogenic relevance in nephrolithiasis. We performed a prospective cross-sectional observational controlled study in 150 recurrent kidney stone formers (rKSF) to analyse the association of sclerostin with known stone risk factors and important modulators of calcium-phosphate metabolism. Serum sclerostin levels were determined at the first visit. As controls, we used 388 non-stone formers from a large Swiss epidemiological cohort. Sclerostin was mildly increased in rKSF in comparison to controls. This finding was more pronounced in women compared to men. Logistic regression indicated an association of serum sclerostin with rKSF status. In hypercalciuric individuals, sclerostin levels were not different from normocalciuric patients. In Spearman correlation analysis we found a positive correlation between sclerostin, age, and BMI and a negative correlation with eGFR. There was a weak correlation with iPTH and intact FGF 23. In contrast, serum sclerostin levels were not associated with 25-OH Vitamin D3, 1,25-dihydroxy-Vitamin D3, urinary calcium and phosphate or other urinary lithogenic risk factors. This is the first prospective controlled study investigating serum sclerostin in rKSF. Sclerostin levels were increased in rKSF independent of hypercalciuria and significantly associated with the status as rKSF. It appears that mechanisms other than hypercalciuria may be involved and thus further studies are required to elucidate underlying pathways.

MP16-20 ASYMPTOMATIC SPONTANEOUS STONE PASSAGE IS FREQUENT IN RECURRENT KIDNEY STONE FORMERS: RESULTS OF THE PROSPECTIVE, RANDOMIZED NOSTONE TRIAL

You have accessJournal of UrologyCME1 Apr 2023MP16-20 ASYMPTOMATIC SPONTANEOUS STONE PASSAGE IS FREQUENT IN RECURRENT KIDNEY STONE FORMERS: RESULTS OF THE PROSPECTIVE, RANDOMIZED NOSTONE TRIAL Kevin Stritt, Olivier Bonny, Daniel Fuster, Andreas Christe, and Beat Roth Kevin StrittKevin Stritt More articles by this author , Olivier BonnyOlivier Bonny More articles by this author , Daniel FusterDaniel Fuster More articles by this author , Andreas ChristeAndreas Christe More articles by this author , and Beat RothBeat Roth More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003236.20AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Kidney stones are a common healthcare problem, and both prevalence and incidence are increasing worldwide. Kidney stone recurrences are frequent. Still, a number of kidney stones pass without symptoms and are not noticed by the patient. Data are limited regarding the frequency of asymptomatic spontaneous stone passage. The aim of the study is to evaluate the frequency of asymptomatic spontaneous stone passage and its predictive factors. METHODS: We analyzed the data from the NOSTONE trial, a prospective, multicenter, double-blind, placebo-controlled randomized trial to assess the efficacy of hydrochlorothiazide (HCT) in the prevention of recurrence in patients with recurrent calcium containing kidney stones. We identified all asymptomatic spontaneous stone passages by comparing the total number of kidney stones on low-dose non-intravenous contrast CT imaging at the beginning and at the end of the 3-year follow-up, taking into account the symptomatic spontaneous stone passages and the surgical stone removals. Association of independent variables identified in the data set and the number of asymptomatic spontaneous stone passages using linear regression analyses. RESULTS: A total of 416 patients were randomized and included in the NOSTONE trial, 5 outliers were removed, therefore we analyzed 411 patients. Median follow-up was 35 months (IQR: 29 – 41); median patient age was 49 years (IQR: 39 – 55); 84/411 (20%) patients were female. A total of 476 stone events occurred in 224 of 411 patients (55%); 245/476 (52%) were symptomatic spontaneous stone passages, 73/476 (15%) were surgical stone removals, and 158/476 (33%) were asymptomatic spontaneous stone passages. The median size of asymptomatic stones (2.4 mm; IQR: 1.95-3.4) and the size of symptomatic stones (2.15 mm; IQR: 1.68-2.79) that passed spontaneously were not significantly different (p=0.366). The number of asymptomatic spontaneous stone passages was significantly influenced by a higher number of stones on CT imaging at randomization (p=0.001) and a lower total stone volume (p=0.001). CONCLUSIONS: Stone recurrence in recurrent calcium containing kidney stone formers is high. A relevant number of stones, however, pass spontaneously, many of these being asymptomatic (39%). Predictive factors for asymptomatic spontaneous stone passages are the number and the total volume of stones. Our data presented should encourage urologists to counsel patients about the possibility of a conservative approach if kidney stones are present. Source of Funding: none © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e210 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Kevin Stritt More articles by this author Olivier Bonny More articles by this author Daniel Fuster More articles by this author Andreas Christe More articles by this author Beat Roth More articles by this author Expand All Advertisement PDF downloadLoading ...

A symptomatic spontaneous stone passage is frequent in recurrent kidney stone formers: Results of the prospective, randomized NOSTONE trial

A symptomatic spontaneous stone passage is frequent in recurrent kidney stone formers: Results of the prospective, randomized NOSTONE trial

The correlation between promoter hypermethylation of VDR, CLDN, and CasR genes and recurrent stone formation

ObjectivesRecurrent Kidney stone formation is a main medical problem imposing a significant burden on both healthcare and the economy worldwide. Environmental and genetic factors have been linked to a bigger risk of kidney stone formation. We aim to assess the role of methylation on recurrent stone formation in three target genes.MethodsWe aimed to check the association between promoter hypermethylation vitamin D receptor (VDR), calcium-sensing receptor (CaSR), and claudin 14 (CLDN14) genes in recurrent kidney stones. We enrolled 30 consecutive recurrent kidney stone formers (age 18–60 years) (cases) and 30 age and gender-matched controls.3. To identify promoter methylation, two target regions from each candidate gene were bisulfited after blood collection and DNA extraction. Methylation quantification was done through methylation-specific high resolution melting (MS-HRM).ResultsThe mean age of the patients and controls (mean ± SD) was 49.58 ± 14.23 years and BMI 36.12 ± 2.72. The methylation status in all six target regions was meaningfully different between the stone-former group and controls when methylation was considered in three clusters of unmethylated, methylated, and hypermethylated. A higher effect in VDR and CLDN was observed compare to CasR (p-value < 0.001, and < 0.005 versus p-value < 0.256).ConclusionsMethylation as an important epigenetic mechanism should be considered more in recurrent stone formations. Promoter hypermethylation of VRD and CLDN genes may have an essential role in recurrent kidney stones formations.

MO040: Development of BBP-711, a small molecule inhibitor of glycolate oxidase for primary hyperoxaluria type 1 and recurrent kidney stone formers

Abstract BACKGROUND AND AIMS BBP-711 is an investigational small molecule inhibitor of glycolate oxidase (GO), currently in development for the treatment of primary hyperoxaluria type 1 (PH1) and recurrent nephrolithiasis. Selection of BBP-711 as a drug candidate followed structural activity optimization and a pharmacological testing strategy that included functional activity in enzyme assays, target engagement in cellular assays and efficacy studies in a rodent model (Agxt−/− mice) of primary hyperoxaluria type 1. METHOD BBP-711 was developed by iterative synthesis and study of the structure–activity relationship of more than 50 GO inhibitors. Lead molecules including BBP-711 were assessed for functional activity by determining inhibition of the conversion of glycolate to oxalate with purified human, mouse and rat HAOX1 enzymes. The ability of BBP-711 to bind directly to immobilized purified hGO (HAOX1 gene product) was evaluated by surface plasmon resonance. Selectivity of BBP-711 was assessed by determining its inhibition of several physiologically related gene products including that from HAOX2. In vitro efficacy of BBP-711 was tested via inhibition of oxalate production in primary hepatocytes cultured from hyperoxaluric Agxt−/− mice. In vivo efficacy of BBP-711 on urinary oxalate excretion was assessed at various doses given by oral gavage in Agxt −/− mice. Pharmacokinetics of BBP-711 was investigated to assess plasma and liver concentrations associated with efficacy. RESULTS BBP-711 is a potent inhibitor of human, rat and mouse GO (IC50 = 15.4 nM, 22.4 nM and 149 nM, respectively). BBP-711 demonstrated stronger direct binding to hGO1 (KD = 6.31 nM) than to rGO2 (KD = 12.8 nM), indicating its preference for GO1 as a target. BBP-711 specificity was demonstrated with &amp;lt;10% activity against off-target enzymes D-amino acid oxidase, dihydroorotate dehydrogenase and lactate dehydrogenase-A at 10 µM. BBP-711 demonstrated concentration-dependent inhibition of oxalate production by Agxt−/− hepatocytes (IC50 = 24.2 nM at 24 hours, IC50 = 42.9 nM at 48 hours). When orally dosed at 7 mg/kg for 5 days in Agxt−/− mice, BBP-711 produced a maximum reduction of urinary oxalate (60%) as well as maximum inhibition of GO activity (&amp;gt;88%). Higher doses did not result in greater reduction in urinary oxalate. Liver exposures (AUC0-24hr) were higher than plasma exposures at all doses tested. GO engagement by BBP-711 was also assessed in an ex vivo assay. Liver extracts from Agxt−/− and wild-type mice dosed with BBP-711 show a dose-dependent reduction in ex vivo GO activity at 1 and 4-hour post-dose. CONCLUSION Iterative and rational optimization of small molecule GO inhibitors resulted in BBP-711, a potent and specific inhibitor of GO with drug-like properties.

MP18-09 COMPARISON OF INTRAOPERATIVE TO LAB-BASED STONE COMPOSITION ANALYSIS AND IMPACT ON MEDICAL MANAGEMENT

You have accessJournal of UrologyStone Disease: Surgical Therapy II (MP18)1 Sep 2021MP18-09 COMPARISON OF INTRAOPERATIVE TO LAB-BASED STONE COMPOSITION ANALYSIS AND IMPACT ON MEDICAL MANAGEMENT Nilang Shah, Sriniwasan Mani, and Noah Canvasser Nilang ShahNilang Shah More articles by this author , Sriniwasan ManiSriniwasan Mani More articles by this author , and Noah CanvasserNoah Canvasser More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002003.09AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Appropriate medical management of recurrent kidney stone formers is reliant on both a stone analysis and a 24-hour urine collection. However, the accuracy of lab-based compositional stone analysis can be variable due to the amount of stone sample provided and differences in analytic methods. During ureteroscopy, given the ability to assess the entire stone for color, durility, how it fragments, and homogeneity or heterogeneity, a unique opportunity exists to predict stone composition. The present study focused on comparing the intraoperative stone composition to lab-based assessment and its subsequent effect on medical management. METHODS: Data was collected on all patients undergoing ureteroscopy from July 2019 until July 2020 for the treatment of renal and/or ureteral stones. During ureteroscopy we extract all stone fragments and submit all for stone analysis. Patient demographics, stone sizes, intraoperative assessment, lab-based stone analysis, initial post-operative 24-hour urinalyses and medical management were recorded. Primary outcome was the accuracy of the intraoperative assessment for dominant (≥50%) stone type and all constituents. Secondary outcome was the accuracy of the intraoperative assessment to guide management of the 24-hour urine abnormality. RESULTS: A total of 187 patients underwent ureteroscopy. Table 1 lists patient demographics and stone details (include age, race, % gender, target stone size, % bilateral, etc.). Intraoperative assessment matched the lab analysis in 97 patients (overall 51%). In the non-matching cases, the intraoperative assessment matched the majority composition of the stone in 64 cases (overall 34%), but not all constituents were identified. The most common inaccuracy was not identifying a calcium phosphate component in a calcium oxalate dominant stone (20%). Overall, intraoperative assessment guided medical management accurately in 88% of cases. CONCLUSIONS: Intraoperative stone assessment serves as a useful adjunct during ureteroscopy. Although accuracy for the dominant stone type and all stone constituents was only 51%, the assessment accurately guides medical management in most cases. This can be helpful in cases where obtaining a complete stone sample is not possible. Source of Funding: None © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e321-e321 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Nilang Shah More articles by this author Sriniwasan Mani More articles by this author Noah Canvasser More articles by this author Expand All Advertisement Loading ...

Complementary and Alternative Medicine Use in First-time and Recurrent Kidney Stone Formers

To describe the patterns of complementary and alternative medicine (CAM) among patients with kidney stones and analyze the alkali content of commonly used CAM therapies. We prospectively conducted structured interviews with patients who presented to a specialty stone clinic for the management of kidney stones. Open-ended questions were used to elicit information regarding CAM knowledge, formulation/dosing, and patterns of use. Several common CAM therapies were then analyzed for their alkali, organic anion, and sugar content. Of 103 subjects, 82 (80%) patients reported knowledge of CAM and 52 (50%) reported using CAM. Patients with recurrent kidney stones were more likely to report using CAM than patients with first-time episodes (56% vs 26%, P = 0.04). Some respondents reported their condition decreased in severity or frequency since starting CAM therapy (17%) and improvements in pain (12%). Total alkali content per serving of the tested supplements was 0 mEq (Stonebreaker), 1.5 mEq (Ocean Spray Cranberry Juice Cocktail), 4.7 mEq (Lakewood Pure Cranberry Juice), 0.6 mEq (Braggs Apple Cider Vinegar), 11.9 mEq (LithoBalance), 9.5 mEq (Simply Grapefruit Juice), 19.8 mEq (KSP-Key Lime), and 20.2 mEq (KSP-Very Berry). Patients with kidney stones may use CAM to alleviate symptoms or prevent recurrence. Commercially available CAM therapies may contain comparable alkali content to commonly prescribed citrate therapy. These data suggest that providers should be prepared to discuss the role of CAM with their patients.

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

BackgroundKidney 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.MethodsWe 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.ResultsOf 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.ConclusionA 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.

041 - Abnormal 24 hour urine increases risk for volatile stone biochemistry in recurrent kidney stone formers

041 - Abnormal 24 hour urine increases risk for volatile stone biochemistry in recurrent kidney stone formers

Vascular calcification and bone mineral density in recurrent kidney stone formers.

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.

Vitamin D Status in Patients with Recurrent Kidney Stones

Data regarding the prevalence of 25-hydroxyvitamin D (25(OH)D) insufficiency in patients with nephrolithiasis, and the effects of vitamin D supplementation on parathyroid hormone (PTH) are few and conflicting. In this article, we examined the prevalence of vitamin D insufficiency and deficiency in 236 recurrent kidney stone formers and the correlation of vitamin D levels with other parameters of stone formation. The prevalent stone composition was calcium oxalate (80.4%) and uric acid (16.45%). One third of stone formers had vitamin D insufficiency and a quarter of them high PTH levels (PTH >7.5 pmol/l) with normal serum (total and ionized) calcium values. Predictor of high PTH was low 25(OH)D level (r = 0.989, r² = 0.977, p < 0.001). Stone formers with hypercalciuria had higher 25(OH)D values (72.26 ± 4.21 vs. 59.29 ± 1.76, p = 0.0013) compared to stone formers with urine calcium within normal ranges. Further studies are needed in order to better define the consequences of vitamin D insufficiency and to evaluate the impact of the therapeutic interventions in this cohort.

Increased Water Intake as a Prevention Strategy for Recurrent Urolithiasis: Major Impact of Compliance on Cost-Effectiveness

We evaluated the economic impact of preventing recurrent stones using a strategy of increased water intake and determined the impact of compliance on cost-effectiveness for the French health care system. A Markov model was constructed to compare costs and outcomes for recurrent kidney stone formers with less than 2 L vs 2 L or more daily fluid intake. Model assumptions included an annual prevalence of 120,000 stone episodes in France, 14.4% annual risk of stone recurrence and a 55% risk reduction in subjects with adequate water intake. Costs were based on resource use as estimated by a panel of experts and official national price lists. Outcomes were from the perspective of the public health payer, and encompassed direct and indirect costs. The total cost of an episode of urolithiasis was estimated at €4,267 including the cost of treatment and complications. This corresponds to an annual budget impact of €88 million for recurrent stones based on 21,000 stone events. Assuming 100% compliance with fluid intake recommendations of 2 L daily, 11,572 new stones might be prevented, resulting in a cost savings of €49 million. Compliance with water intake in only 25% of patients would still result in 2,893 fewer stones and a cost savings of €10 million. Varying the costs of managing stones had a smaller impact on outcomes since in many patients stones do not form. Varying the incidence of complications did not change the incidence of stones and had a negligible effect on overall cost. Preventing recurrent urolithiasis has a significant cost savings potential for a payer as a result of a reduced stone burden. However, compliance is an important factor in determining cost-effectiveness.

Causes of autonomic dysfunction in idiopathic recurrent kidney stone formers

A higher prevalence of hypertension and adverse cardiovascular outcomes has been reported in kidney stone formers (KSF). We performed this study with the purpose of evaluating the autonomic nervous system (ANS) activity in KSF. We performed a 70° head-up tilt test in 30 idiopathic recurrent KSF aged 45.6 ± 12.1 years old (17 men: 13 women) and 30 healthy controls aged 42.0 ± 12.4 years old (17 women: 13 men). Thirteen KSF were hypertensive, and 17 were normotensive. Blood pressure (BP) and heart rate variability (HRV) were used for the non-invasive assessment of the efferent activity of the ANS. Discrete wavelet transform (DWT) was used to quantify the low-frequency (LF: 0.04-0.15 Hz) and high-frequency (HF: 0.15-0.4 Hz) components during several periods of tilt. The results showed significantly higher HR and BP in KSF, in both supine and tilt positions. DWT revealed diminished HRV in the kidney stone patients during head-up tilt, with no increase in the LF and greater decrease in the HF components. The differences in the HF component of HRV were associated with obesity and hyperuricosuria, but the abnormalities of the LF component were independent of the explanatory variables. The LF component of systolic BP was significantly higher in KSF and was associated with hypertension. Several factors may contribute to the presence of autonomic dysfunction in patients with recurrent nephrolithiasis. This abnormality has significant implications in cardiovascular risk assessment and treatment planning.

Effect of Cystone® on urinary composition and stone formation over a one year period

Kidney stones are a common problem for which inadequate prevention exists. We recruited ten recurrent kidney stone formers with documented calcium oxalate stones into a two phased study to assess safety and effectiveness of Cystone(®), an herbal treatment for prevention of kidney stones. The first phase was a randomized double-blinded 12 week cross over study assessing the effect of Cystone(®) vs. placebo on urinary supersaturation. The second phase was an open label one year study of Cystone(®) to determine if renal stone burden decreased, as assessed by quantitative and subjective assessment of CT. Results revealed no statistically significant effect of Cystone(®) on urinary composition short (6 weeks) or long (52 weeks) term. Average renal stone burden increased rather than decreased on Cystone(®). Therefore, this study does not support the efficacy of Cystone(®) to treat calcium oxalate stone formers. Future studies will be needed to assess effects on stone passage, or on other stone types.

Urindiagnostik bei Nephrolithiasis – Interpretation und therapeutische Konsequenzen

Nephrolithiasis is a disease with a high and even rising incidence. It has a high morbidity, generates high costs and has a high recurrence rate. Urinalysis is of importance especially in recurrent stone formers. It allows the identification and quantification of risk factors and the establishment of individual risk profiles. Based on these individual risk profiles, rational therapy for metaphylaxis of kidney stones lowers stone recurrence rates significantly. This review article aims to give a focussed overview of the most important risk factors for kidney stones and reasonable urine tests for evaluation of recurrent kidney stone formers.

Recurrent kidney stones: causes and diagnostic criteria in patients from Campania (southern Italy).

A study was carried out on 180 recurrent kidney stone formers from the Campania region of southern Italy. The data showed that this hypercalciuric population was similar to that in previous studies; however, there was no difference in terms of parathyroid activity when compared with normal controls. The slightly depressed serum levels of vitamin D in hypercalciurics indicate that gut calcium absorption is not directly related to vitamin D levels. We found no difference in the prevalence of metabolic abnormalities associated with stone formation between the patients in this series and those in previous studies.