Association of metabolic syndrome traits and severity of kidney stones: results from a nationwide survey on urolithiasis in Japan

Analysis of metabolic syndrome in bilateral upper urinary tract stones: A retrospective study of 3905 cases

Bilateral upper urinary tract stones are significantly related to renal function damage. However, few studies characterized the risk factors of bilateral upper urinary tract stones. We retrospectively enrolled 3905 patients with urinary tract stones from March 2019 to March 2022 at the Second Hospital of Tianjin Medical University. Patients were divided into two groups according to the location of the stones, and the related data were evaluated. In this study, 2485 unilateral and 1420 bilateral stone patients were included. Multivariate logistic regression analysis showed that BMI, gout, hyperparathyroidism, uric acid stone, urine PH, 24-h urinary calcium, blood uric acid, and metabolic syndrome (Mets) were independent risk factors for bilateral stone formation(P < 0.05). Based on these results, we construct a discrimination model. This model revealed good discrimination with an area under the receiver operating characteristic curves of 0.617, and the sensitivity and specificity were 0.592 and 0.586, respectively. Furthermore, the number of Mets components increased the risk of bilateral upper urinary tract stones. Hypertension, hyperglycemia, and low HDL level were strongly associated with bilateral upper urinary tract stones (P < 0.05). Patients with 5 components Mets had 1.89-fold higher risk of bilateral upper urinary tract stones than those with 1 component Mets (OR 3.381; 95 % CI 1.221-9.360; P = 0.013). Additionally, male patients with Mets had higher risk of bilateral upper urinary tract stones than female patients. Our analysis revealed that eight clinical factors were associated with the formation of bilateral upper urinary tract stones, namely BMI, gout, hyperparathyroidism, uric acid stone, urine PH, 24-h urinary calcium, blood uric acid, and Mets. This study could help clinicians adjust treatment strategies for high-risk patients with bilateral upper urinary tract stones.

Basal metabolic rate and the risk of urolithiasis: a two-sample Mendelian randomization study

OBJECTIVE

Few studies have investigated the impact of basal metabolic rate (BMR) on the development of urolithiasis, and the causal relationship is yet to be established. In this study, a two-sample Mendelian randomization (MR) analysis was utilized to identify the causal relationship between BMR and risk of urolithiasis.

METHOD

Genetic instruments for BMR were drawn from a public genome-wide association study (GWAS). Summary dates on BMR and urolithiasis were obtained from a GWAS meta-analysis with sample sizes of 454,874 and 212,453, respectively. The inverse-variance weighted (IVW) method was provided as the main approach to estimate the causal relationship. The weighted-median method and the MR-Egger method were used as supplements to the IVW method. In addition, we conducted sensitivity analyses, including heterogeneity tests, pleiotropy tests and leave-one-out analysis, to assess the robustness of the outcomes. Furthermore, the funnel plot asymmetry was visually inspected to evaluate possible bias.

RESULTS

The inverse-variance weighted data revealed that genetically predicted BMR significantly decreased the risk of urolithiasis [beta coefficient (beta): - 0.2366, odds ratio (OR): 0.7893, 95% confidence interval (CI) 0.6504-0.9579, p = 0.0166].

CONCLUSIONS

BMR has causal effects on urolithiasis in an MR study, and the risk of urolithiasis in patients with lower levels of BMR is higher.

The association between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and kidney stones: a cross-sectional study

BACKGROUND

The relationship between the NHHR and kidney stone risk remains unknown. The purpose of this study was to evaluate the association between adult NHHR and kidney stone occurrence in USA.

METHODS

This study used a variety of statistical techniques such as threshold effects, subgroup analysis, smooth curve fitting, multivariate logistic regression, and data from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2014. We aimed to clarify the relationship between the NHHR and kidney stone risk.

RESULTS

The average age of the 21,058 individuals in this research was 49.70 ± 17.64 years. The mean NHHR was 3.00 ± 1.47, and the overall prevalence of kidney stone occurrence was 9.05%. The prevalence within the quartile ranges (Q1-Q4) was 7.01%, 8.71%, 9.98%, and 10.49%, respectively. The overall average recurrence rate of kidney stones was 3.05%, demonstrating a significant increase with increasing NHHR (Q1: 1.92%, Q2: 2.92%, Q3: 3.35%, Q4: 4.00%, P < 0.01). The occurrence of kidney stones increased by 4% (95% CI: 1.00-1.08, P = 0.0373) and the chance of recurrence increased by 9% (95% CI: 1.03-1.14, P < 0.01) with each unit increase in NHHR. The interaction analysis results demonstrated that the relationship between the NHHR and the risk of kidney stones was not significantly impacted by the following factors: sex, body mass index, poverty income ratio, diabetes, or hypertension. Curve fitting and threshold effect analysis also demonstrated a non-linear association, with a breakpoint found at 3.17, between the NHHR and the risk of kidney stones.

CONCLUSIONS

In adults in the USA, there is a substantial correlation between elevated NHHR levels and a higher probability of kidney stones developing and recurring. Timely intervention and management of NHHR may effectively mitigate the occurrence and recurrence of kidney stones.

Impact of Metabolic Syndrome on Post-Operative Infection in Patients Undergoing Flexible Ureteroscopy Lithotripsy

Background: To investigate retrospectively whether metabolic syndrome (MetS) of flexible ureteroscopy (fURS) lithotripsy can be used to predict post-operative infection. Patients and Methods: After screening, 1,110 patients who received fURS lithotripsy for upper urinary tract stones in our center between January 2015 and December 2022 were analyzed retrospectively. Patients were divided into MetS-positive group and MetS-negative group. Post-operative infection was divided into fever, urosepsis, and septic shock. Relevant data during the peri-operative period were collected. Univariable and multivariable logistic regression analyses were adopted to estimate the impact of metabolic syndrome on post-operative infection in patients undergoing fURS lithotripsy. Results: Among the 1,110 patients, 427 tested positive for MetS, whereas 683 tested negative. Eighty-eight patients suffered from fever (67 patients in the MetS-positive group and 21 in the MetS-negative group). Forty-nine patients had urosepsis (29 patients in the MetS-positive group and 20 in the MetS-negative group), of whom seven patients developed septic shock. No patient developed multiple organ failure or died because of infection. The prevalence of post-operative infections in the MetS-positive group was higher than that in the MetS-negative group (p < 0.001). Multivariable logistic regression analyses showed that diabetes mellitus, MetS-positive, positive urine culture, and longer operation time were positively correlated with post-operative fever. Positive MetS, positive urine culture, and longer operation time were strongly correlated with post-operative urosepsis. Conclusions: Metabolic syndrome was found to be associated with post-operative infection in patients undergoing fURS lithotripsy, suggesting it can serve as a predictive factor.

Serum HDL partially mediates the association between exposure to volatile organic compounds and kidney stones: A nationally representative cross-sectional study from NHANES

Environmental exposure to volatile organic compounds (VOCs) is ubiquitous, and this study explored whether exposure to VOCs is associated with the risk of kidney stones. We performed a nationally representative US cross-sectional study using data from five survey cycles (2011-2020) of the National Health and Nutrition Examination Survey (NHANES) program. Exposure to VOCs was determined by urine creatinine-corrected metabolites of VOCs (mVOCs). In total 5505 participants and 15 urine mVOCs were included for analysis, and the prevalence of kidney stones was 9.57 % (527/5505). Multivariable logistic regression showed that urine AMCC (parent VOCs (pVOCs): N, N-Dimethylformamide), 3,4-MHA (pVOCs: xylene), MA (pVOCs: ethylbenzene; styrene), DHBMA (pVOCs: 1,3-butadiene), HMPMA (pVOCs: crotonaldehyde) and 2HPMA (pVOCs: propylene oxide) were significantly associated with an increased risk of kidney stones in US general population. Sub-analysis revealed that there was a more pronounced association in women and the overweight/obesity group (body mass index ≥ 25). Moreover, the weighted quantile sum (WQS) regression model and the Bayesian kernel machine regression (BKMR) model consistently identified a positive association between co-exposure to VOCs and the risk of kidney stones, in which AMCC played the most important role among the 15 mVOCs. Mediation analysis further identified serum high-density lipoprotein cholesterol (HDL) as a mediator of the association between VOC co-exposure and kidney stones. Our study draws attention to the previously unknown positive associations between non-occupational VOC exposure and the risk of kidney stones in the general population. However, further studies are required to clarify the existence of such causation.

Causal effects of circulating lipids and lipid-lowering drugs on the risk of urinary stones: a Mendelian randomization study

Background

Previous studies have yielded conflicting findings regarding the association between circulating lipids and lipid-lowering drugs with urinary stones, and the causal relationship between the two remains inconclusive.

Objective

This study aimed to assess the causal relationship between circulating lipids (Triglycerides [TG], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], apolipoprotein A [APOA], apolipoprotein B [APOB] and Pure hypercholesterolaemia), lipid-lowering drugs (HMGCR [HMG-CoA reductase] inhibitors and PCSK9[Proprotein Convertase Subtilisin/Kexin Type 9] inhibitors) and the risk of urinary stones, using genetic data.

Methods

Genetic instrumental variables (GIVs) for circulating lipids and lipid-lowering drugs were obtained from the UK Biobank and existing literature. Outcome data were extracted from a genetic association database with 3,625 urinary stone cases and 459,308 controls. Two-sample MR analysis, employing the TwoSampleMR software package in R 4.2.3, was conducted to assess the associations between multiple exposures. The primary outcome was determined using the inverse variance weighted (IVW) method for the causal relationship between exposure and outcome, while additional methods such as MR-Egger, weighted median, simple mode, and weighted mode were utilized as supplementary analyses. Robustness of the Mendelian Randomization (MR) analysis results was assessed through leave-one-out analysis and funnel plots.

Results

The MR analysis revealed a significant association between elevated TG levels per 1 standard deviation and the occurrence of urinary stones (odds ratio [OR]: 1.002, 95% confidence interval [CI]: 1.000-1.003, P = 0.010). However, no significant association was observed between factors other than TG exposure and the risk of urinary stone occurrence across all methods(LDL-C: [OR], 1.001; 95% [CI], 1.000-1.003, P=0.132;HDL-C: [OR], 0.999; 95% [CI], 0.998-1.000, P=0.151;APOA:[OR] being 1.000 (95% [CI], 0.999-1.001, P=0.721;APOB: [OR] of 1.001 (95% [CI], 1.000-1.002, P=0.058;Pure hypercholesterolaemia: [OR] of 1.015 (95% [CI], 0.976-1.055, P=0.455) and lipid-lowering drugs (HMGCR inhibitors: [OR], 0.997; 95% [CI], 0.990-1.003, P=0.301 and PCSK9 inhibitors:[OR], 1.002; 95% [CI], 1.000-1.005, P=0.099).

Conclusion

Our findings provide conclusive evidence supporting a causal relationship between an increased risk of urinary stones and elevated serum TG levels. However, we did not find a significant association between urinary stone occurrence and the levels of LDL-C, HDL-C, APOA, APOB, Pure hypercholesterolaemia and lipid-lowering drugs.

Metabolomic profiles and pathogenesis of nephrolithiasis

PURPOSE OF REVIEW

Kidney stone disease is caused by supersaturation of urine with certain metabolites and minerals. The urine composition of stone formers has been measured to prevent stone recurrence, specifically calcium, uric acid, oxalate, ammonia, citrate. However, these minerals and metabolites have proven to be unreliable in predicting stone recurrence. Metabolomics using high throughput technologies in well defined patient cohorts can identify metabolites that may provide insight into the pathogenesis of stones as well as offer possibilities in therapeutics.

RECENT FINDINGS

Techniques including 1H-NMR, and liquid chromatography paired with tandem mass spectroscopy have identified multiple possible metabolites involved in stone formation. Compared to formers of calcium oxalate stones, healthy controls had higher levels of hippuric acid as well as metabolites involved in caffeine metabolism. Both the gut and urine microbiome may contribute to the altered metabolome of stone formers.

SUMMARY

Although metabolomics has offered several potential metabolites that may be protective against or promote stone formation, the mechanisms behind these metabolomic profiles and their clinical significance requires further investigation.

Nephrolithiasis is associated with the severity of coronary artery calcification, but not with coronary artery stenosis

PURPOSE

Emerging data have indicated that nephrolithiasis is possibly associated with subclinical coronary artery disease (CAD). Considering that a significant proportion of obstructive CAD in non-elderly individuals occurs in those without detectable calcium score (CACS), this study aimed to investigate whether nephrolithiasis is still associated with CAD as assessed by coronary computed tomography (CT)-derived luminal stenosis [using Gensini score (GS)].

METHODS

A total of 1170 asymptomatic adults without known CAD who underwent health examinations were recruited. Nephrolithiasis was assessed using abdominal ultrasonography (US). Individuals with a self-reported stone history, but no evidence of nephrolithiasis were excluded. The CACS and GS were measured using 256-slice coronary CT.

RESULTS

Nearly half of these patients had a CACS > 0 (48.1%), and a higher prevalence of nephrolithiasis was observed than in those who had zero CACS (13.1% vs. 9.7%). However, no significant intergroup difference in GS was detected. A greater proportion of stone formers than non-stone formers had a higher risk category, whereas no significant difference was noted in Gensini category. Multiple linear regression analyses showed that the CACS independently predicted the presence of nephrolithiasis after adjustment. Importantly, we found that stone formers had a nearly threefold higher risk than non-stone formers of developing severe coronary calcification (CAC > 400).

CONCLUSIONS

Nephrolithiasis was significantly associated with coronary artery calcification presence and severity, but not coronary luminal stenosis in patients without known CAD. Accordingly, the relationship between stone disease and CAD remains controversial, and additional studies are imperative to validate these findings.

Causal relationship in gut microbiota and upper urinary urolithiasis using Mendelian randomization

Background

Several reports in recent years have found an association between gut microbiota and upper urinary urolithiasis. However, the causal relationship between them remains to be clarified.

Methods

Genetic variation is used as a tool in Mendelian randomization for inference of whether exposure factors have a causal effect on disease outcomes. We selected summary statistics from a large genome-wide association study of the gut microbiome published by the MiBioGen consortium with a sample size of 18,340 as an exposure factor and upper urinary urolithiasis data from FinnGen GWAS with 4,969 calculi cases and 213,445 controls as a disease outcome. Then, a two-sample Mendelian randomization analysis was performed by applying inverse variance-weighted, MR-Egger, maximum likelihood, and weighted median. In addition, heterogeneity and horizontal pleiotropy were excluded by sensitivity analysis.

Results

IVW results confirmed that class Deltaproteobacteria (OR = 0.814, 95% CI: 0.666-0.995, P = 0.045), order NB1n (OR = 0.833, 95% CI: 0.737-0.940, P = 3.15 × 10^-3), family Clostridiaceae1 (OR = 0.729, 95% CI: 0.581-0.916, P = 6.61 × 10^-3), genus Barnesiella (OR = 0.695, 95% CI: 0.551-0.877, P = 2.20 × 10^-3), genus Clostridium sensu_stricto_1 (OR = 0.777, 95% CI: 0.612-0.986, P = 0.0380), genus Flavonifractor (OR = 0.711, 95% CI: 0.536-0.944, P = 0.0181), genus Hungatella (OR = 0.829, 95% CI: 0.690-0.995, P = 0.0444), and genus Oscillospira (OR = 0.758, 95% CI: 0.577-0.996, P = 0.0464) had a protective effect on upper urinary urolithiasis, while Eubacterium xylanophilum (OR =1.26, 95% CI: 1.010-1.566, P = 0.0423) had the opposite effect. Sensitivity analysis did not find outlier SNPs.

Conclusion

In summary, a causal relationship was found between several genera and upper urinary urolithiasis. However, we still need further randomized controlled trials to validate.

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.

Increased renal uptake and urine excretion of oxidized LDL is possibly associated with formation of large calcium oxalate nephrolithiasis: a preliminary study

PURPOSE

Growing evidence have suggested an association between nephrolithiasis and cardiovascular disease (CVD) with unclear mechanism. Oxidized low-density lipoproteins (oxLDL) induces atherosclerosis and was found to be the possible link between these two diseases. Our study aimed to examine the serum, urine and kidney expression of oxLDL in relation to large calcium oxalate (CaOx) renal stone disease.

METHODS

A total of 67 large CaOx dominant renal stone patients and 31 stone-free controls were enrolled in the prospective case-control study. All participants were without known CVD history. Serum, urine, and kidney biopsy were collected before and during percutaneous nephrolithotomy, respectively. Enzyme-linked immunosorbent assays were used to assess serum and urine oxLDL, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), and high-sensitivity C-reactive protein (hsCRP).

RESULTS

There was no significantly difference in circulating oxLDL, but serum hsCRP was significantly near two-fold higher in nephrolithiasis patients. Serum hsCRP was also correlated with stone maximal length. Urine oxLDL was significantly higher in the nephrolithiasis group and correlated with serum hsCRP and stone maximal length. Increased oxLDL uptake in kidney was found in nephrolithiasis patients, whereas no significantly renal expression of oxLDL was observed in controls.

CONCLUSIONS

The renal uptake of oxLDL with increased oxLDL excretion from large CaOx renal stone formers, independent of increased circulating oxLDL, is a novel pathological finding in kidney stone disease and brings attention to the possible involvement of renal steatosis in the process of urolithiasis formation.

Metabolic Syndrome and Nephrolithiasis; A Cross Sectional Population-based Study on the Baseline Data of the PERSIAN Kavar Cohort Study

OBJECTIVE

To explore the relationship between metabolic syndrome and its components with nephrolithiasis.

METHODS

In current study, 4,901 individuals from the PERSIAN (Prospective Epidemiological Research Studies in IrAN) Kavar cohort study were included. Metabolic syndrome was defined according to the ATP III criteria (2005 revision). The nephrolithiasis was assessed using a structured questionnaire, and ultrasound findings were reviewed in subjects who reported positive history of nephrolithiasis. We applied logistic regression to estimate the odds ratio (OR) and 95% confidence interval (CI).

RESULTS

The prevalence of nephrolithiasis and metabolic syndrome was 28.5% and 40.91%, respectively. Almost 31% of the patients with metabolic syndrome had a history of nephrolithiasis. Multivariable logistic regression analysis revealed a positive association between metabolic syndrome and nephrolithiasis (OR= 1.30, 95% CI: 1.14-1.49, P<.001) after adjustment age, sex, ethnicity, physical activity, smoking status, and alcohol intake. Furthermore, the relation was higher for elders aged 50 years or more (P for interaction= .016) and Turk Nomad participants (P for interaction= 0.044) than the others. There was also a positive independent association between hypertension (OR=1.29, 95% CI: 1.12-1.48, P<.001) and hypertriglyceridemia (OR= 1.15, 95% CI: 1.01-1.31, P=.033) with nephrolithiasis.

CONCLUSION

In this large sample study, we demonstrate a weak positive association between metabolic syndrome, hypertension, and hypertriglyceridemia with nephrolithiasis.

Nephrolithiasis-Associated Renal Cell Carcinoma in Patients Who Underwent Nephrectomy: A Single-Center Experience

Background

Kidney stones (nephrolithiasis) affect around 5% of the world's population. Some medical disorders, like obesity or diabetes, have increased the incidence and prevalence of nephrolithiasis. In addition, chronic inflammation and infection are frequently linked to kidney stone formation. Urothelial cell proliferation may change as a result of chronic inflammation, tumors will therefore develop as a result of this. The correlation between nephrolithiasis and renal cell cancer can also be explained by shared risk factors. At Adam Malik General Hospital, we strive to identify the risk factor for stone-induced renal cell cancer.

Methods

This study was carried out at Adam Malik General Hospital by collecting medical record reports from patients who had nephrectomy for nephrolithiasis between July 2014 and August 2020. A variety of information was obtained, including identification, smoking status, body mass index (BMI), hypertension, diabetes mellitus, and nephrolithiasis history. The histopathological examination of cancer patients was used to determine adjusted odds ratios (ORs) both separately and in combination with other variables. Age, smoking status, BMI, hypertension, and diabetes mellitus all influenced the OR. The single variable was examined using Chi-square test, and the multivariate analysis was carried out using linear regression.

Results

A total of 84 patients who underwent nephrectomy due to nephrolithiasis were included in the study, with an average age of 48.77 ± 7.23 years old; 48 (60%) of those were aged < 55 years old. In this study, 52 male patients (63.4%) and 16 patients (20%) were found to have renal cell carcinoma. Univariate analysis showed that the OR of patients with familial history of cancer was 4.5 (95% confidence interval (CI) 2.17 - 19.8), and the OR for smokers was 1.54 (95% CI 1.42 - 1.68). Similar results were shown in patients with hypertension and urinary tract infections due to stones. Nephrolithiasis patients with hypertension were 2.56 (95% CI 1.075 - 6.106) times more likely to develop a malignancy, while patients who had an infection due to a urinary tract stone were 2.85 (95% CI 1.37 - 5.92) times more likely to develop renal cell carcinoma compared to its counterpart. Both have a P-value of less than 0.05. Contrarily, alcoholism and frequent nonsteroidal anti-inflammatory drugs (NSAIDs) user results were different. Both have a P-value of 0.264 and 0.07, respectively. Furthermore, diabetes mellitus type 2 and BMI over 25 are not statistically significant, with a P-value of 0.341 and 0.12, respectively. In multivariable-adjusted analyses, participants with a family history of cancer and recurrent urinary tract infection due to urinary tract stones had a statistically significant increase in overall renal cell carcinoma risk (hazard ratio (HR): 1.39, 95% CI 1.05 - 1.84 and HR: 1.12, 95% CI 1.05 - 1.34).

Conclusion

Kidney stone and renal cell carcinoma are significantly correlated due to recurrent urinary tract infection and familial history of cancer, which increases renal cell carcinoma risk.

The ABCG2 rs2231142 polymorphism and the risk of nephrolithiasis: A case-control study from the Taiwan biobank

BACKGROUND

Hyperuricemia and gout are risk factors of nephrolithiasis. However, it is unclear whether the ABCG2 gene contributes to the development of nephrolithiasis. We aimed to investigate the interaction between the ABCG2 rs2231142 variant and incident nephrolithiasis in the Taiwanese population.

METHODS

A total of 120,267 adults aged 30-70 years were enrolled from the Taiwan Biobank data-base in this retrospective case-control study and genotyped for rs2231142. The primary outcome was the prevalence of self-reported nephrolithiasis. The odds ratio (OR) of incident nephrolithiasis was analyzed by multivariable logistic regression models with adjustment for multifactorial confounding factors. Associations of the ABCG2 rs2231142 variant with serum uric acid levels, and the incident nephrolithiasis were explored.

RESULTS

The frequency of rs2231142 T allele was 53%, and 8,410 participants had nephrolithiasis. The multivariable-adjusted OR (95% confidence interval) of nephrolithiasis was 1.18 (1.09-1.28) and 1.12 (1.06-1.18) for TT and GT genotypes, respectively, compared with the GG genotype (p<0.001), specifically in the male population with hyperuricemia. Higher age, male sex, hyperlipidemia, hypertension, diabetes mellitus, hyperuricemia, smoking and overweight were independent risk factors for nephrolithiasis. In contrast, regular physical exercise is a protective factor against nephrolithiasis.

CONCLUSIONS

ABCG2 genetic variation is a significant risk of nephrolithiasis, independent of serum uric acid levels. For rs2231142 T allele carriers, our result provides evidence for precision healthcare to tackle hyperuricemia, comorbidities, smoking, and overweight, and recommend regular physical exercise for the prevention of nephrolithiasis.

A pilot dynamic analysis of formative factors of nephrolithiasis related to metabolic syndrome: evidence in a rat model

Introduction and objective

To examine the dynamic changes in the formative factors of nephrolithiasis and the final micromorphological changes in an obesity-initiated metabolic syndrome (MS) rat model.

Methods

Forty five-week-old male Sprague–Dawley (SD) rats were randomly divided into four groups: the regular diet group (RD), high-fat diet group (HFD), regular diet with drug (ethylene glycol and ammonium chloride) group (RDD), and high-fat diet with drug group (HFDD). A dynamic assessment of MS components (body weight (BW), body length (BL), Lee’s index (LI), blood glucose (BG), total cholesterol (TC), and triglycerides (TGs)) and stone-forming factors (urinary pH, urinary calcium, and urinary oxalate acid) was carried out. In addition, the levels of oxidative stress (OS) markers (CAT, SOD, TAC, GSH-PX, and MDA) were measured, and histological analysis was carried out at the end of 16 weeks.

Results

MS-related parameters, such as BW, LI, BG, TC, and TG, were significantly higher in HFD-fed rats than in RD-fed rats (p < 0.001). In the HFDD group, significantly lower urinary pH, hyperoxaluria, and hypocalciuria were noted in the dynamic assessment of stone-forming factors (p < 0.001). CAT, TAC, and MDA were notably changed in the HFD-fed groups, particularly the HFDD rats. Histological analysis showed that the renal tubules of HFDD rats had the highest scores for both inflammation and renal crystallization deposition (p < 0.05).

Conclusions

Our results suggest that male SD rats with MS are prone to developing nephrolithiasis. Validation in an in vivo model may lead to an understanding of the underlying pathophysiological mechanisms of action of MS-related nephrolithiasis in humans.

Key messages

Male SD rats with metabolic syndrome are more prone to developing calcium oxalate nephrolithiasis after treatment with ethylene glycol and ammonium chloride compared to control lean rats.

MS-related nephrolithiasis in rats induced by ethylene glycol and ammonium chloride is mainly related to increased hyperoxaluria and inflammation and decreased antioxidant levels.

High-fat diet-fed SD rats treated with ethylene glycol and ammonium chloride are a stable and valid in vivo model for understanding the potential mechanism of action of MS-related nephrolithiasis.

Unravelling the Complex Relationship between Diet and Nephrolithiasis: The Role of Nutrigenomics and Nutrigenetics

Nephrolithiasis is an increasingly prevalent condition, especially in high income countries, and is associated with high morbidity. Extraordinary progress in genetics made the identification of genetic forms of nephrolithiasis possible. These genetic diseases are usually rare and do not account for the most common forms of nephrolithiasis that are the result of several factors such as environment, dietary habits, and predisposing genes. This knowledge has shaped what we classify as nephrolithiasis, a condition that is now recognized as systemic. How and to what extent all these factors interact with one another and end in kidney stone formation, growth, and recurrence is not completely understood. Two new research fields have recently been trying to give some answers: nutrigenomics and nutrigenetics. These fields have the aim of understanding the intricate diet/genome interface that influences gene expression regulation mainly through epigenetic mechanisms and results in specific medical conditions such as cancer, metabolic syndrome, and cardiovascular diseases. Epigenetics seems to play a crucial role and could represent the link between environmental factors, that we are constantly exposed to, and risk factors for nephrolithiasis. In this systematic review, we summarize all the available evidence of proven or hypothesized epigenetic mechanisms related to nephrolithiasis.

Association between visceral adiposity index and kidney stones in American adults: A cross-sectional analysis of NHANES 2007–2018

Objective

To explore the association between Visceral Adiposity Index (VAI) and kidney stones in an American adult population.

Materials and methods

National Health and Nutrition Examination Survey (NHANES) datasets from 2007 to 2018 were used. Participants aged ≥20 years who reported kidney stone history and VAI were included. Weighted proportions, multivariable analysis, generalized additive model (GAM), and spline smoothing were used to evaluate the associations between VAI and kidney stones by adjusting gender, age, race, education, marital status, poverty income ratio, smoking, alcohol, high blood pressure, diabetes, congestive heart failure, cancer, vigorous activity, moderate activity, HEI2015 total score, and energy.

Results

Totally 13,871 American adults were included. All the participants were divided by the VAI into four groups according to the quartile: Q1 (11.96–42.89), Q2 (42.90–74.45), Q3 (74.45–131.43), and Q4 (131.45–611.34). The mean ± standard deviation of the VAI in the four groups were Q1 (29.07 ± 8.22), Q2 (57.53 ± 8.81), Q3 (99.52 ± 16.25), and Q4 (225.92 ± 95.83). In the fully adjusted multivariable model, VAI was positively correlated with urolithiasis [odds ratio (OR) = 1.001; 95% confidence interval (CI) 1.000–1.001]. Compared with the first quartile of VAI, the population in the fourth quartile of VAI had a higher prevalence of kidney stones (OR = 1.329; 95% CI 1.104–1.600). Subgroup analysis detected no significant interaction effect after adjusting for covariates.

Conclusion

The value of VAI is positively correlated with the prevalence of kidney stones, which suggest VAI can be used to assess the potential risk of the prevalence of kidney stones.

Nephrolithiasis: A Red Flag for Cardiovascular Risk

Epidemiological evidence shows that nephrolithiasis is associated with cardiovascular (CV) morbidities. The association between nephrolithiasis and CV disease is not surprising because both diseases share conditions that facilitate their development. Metabolic conditions, encompassed in the definition of metabolic syndrome (MS), and habits that promote nephrolithiasis by altering urine composition also promote clinical manifestations of CV disease. By inducing oxidative stress, these conditions cause endothelial dysfunction and increased arterial stiffness, which are both well-known predictors of CV disease. Furthermore, the subtle systemic metabolic acidosis observed in stone formers with CV disease may have a pathogenic role by increasing bone turnover and leading to reduced mineral content and osteoporosis/osteopenia. Heart valves and/or coronary artery and aortic calcifications are frequently associated with reduced mineral density. This is known as the 'calcification paradox' in osteoporosis and has also been observed in subjects with calcium nephrolithiasis. Evidence supports the hypothesis that osteoporosis/osteopenia is an independent risk factor for the development of CV calcifications. In the long term, episodes of renal stones may occur from the onset of metabolic derangements/MS to arterial stiffness/atherosclerosis and CV morbidities. These episodes should be considered a warning sign of an ongoing and silent atherosclerotic process. The evaluation of cardiometabolic risk factors and MS components should be routine in the assessment of renal stone formers. This would allow for treatment and prevention of the development of CV complications, which are much more severe for the patient and for public health.

Systematic assessment of monogenic etiology in adult-onset kidney stone formers undergoing urological intervention-evidence for genetic pretest probability

Kidney stone disease (KSD) is a prevalent condition associated with high morbidity, frequent recurrence, and progression to chronic kidney disease (CKD). The etiology is multifactorial, depending on environmental and genetic factors. Although monogenic KSD is frequent in children, unbiased prevalence data of heritable forms in adults is scarce. Within 2 years of recruitment, all patients hospitalized for urological kidney stone intervention at our center were consecutively enrolled for targeted next generation sequencing (tNGS). Additionally, clinical and metabolic assessments were performed for genotype-phenotype analyses. The cohort comprised 155 (66%) males and 81 (34%) females, with a mean age at first stone of 47 years (4-86). The diagnostic yield of tNGS was 6.8% (16/236), with cystinuria (SLC3A1, SLC7A9), distal renal tubular acidosis (SLC4A1), and renal phosphate wasting (SLC34A1, SLC9A3R1) as underlying hereditary disorders. While metabolic syndrome traits were associated with late-onset KSD, hereditary KSD was associated with increased disease severity in terms of early-onset, frequent recurrence, mildly impaired kidney function, and common bilateral affection. By employing systematic genetic analysis to a less biased cohort of common adult kidney stone formers, we demonstrate its diagnostic value for establishing the underlying disorder in a distinct proportion. Factors determining pretest probability include age at first stone (<40 years), frequent recurrence, mild CKD, and bilateral KSD.

The effect of metabolic risk factors on urinary stone composition: An observational study

To investigate how the risk factors of metabolic diseases affect urinary stone composition, particularly uric acid (UA) stones. Overall, 583 patients with data on urinary stone composition were retrospectively analyzed and classified into UA and nonUA stone formers according to the presence of the UA component. Various factors were compared between both groups. Participants were categorized according to age, glucose level, HbA1c level, and estimated glomerular filtration rate (eGFR) into subgroups, and the incidence of UA stone was compared. Overall, 137 UA stone formers (23.5%) and 446 nonUA stone formers (76.5%) were included. Mean age and male-to-female ratio were higher in the UA group than in the nonUA group. The rates of diabetes mellitus (DM), hypertension, chronic kidney disease, and coronary artery disease, all of which were associated with differences in urinary stone composition, were higher in the UA group than in the nonUA group. The UA group exhibited lower mean eGFR and higher glucose and HbA1c levels. Similarly, the UA group had higher mean UA levels and predictably lower urinary pH. In subgroup analysis, higher age, glucose level, HbA1c level, and lower eGFR were associated with an increased risk of UA stone formation. In the multivariate logistic regression analysis, the UA group showed a significantly higher age (P < .001), DM frequency (P = .049), and HbA1c level (P = .032), but significantly lower eGFR than the nonUA group (P < .001). Age and DM were independent risk factors for UA urolithiasis, implying a relationship between urinary stone composition and metabolic diseases. Additionally, renal function and HbA1c level were risk factors for UA stones.

Insulin Resistance and Urolithiasis as a Challenge for a Dietitian

Many obesity and diet-related diseases have been observed in recent years. Insulin resistance (IR), a state of tissue resistance to insulin due to its impaired function, is a common coexisting condition. The most important predisposing factors are excessive visceral fat and chronic low-grade inflammatory response. However, IR’s pathogenesis is not fully understood. Hence, the diagnosis of IR should be carried out carefully because many different diagnostic paths do not always give equivalent results. An additional disease that is often associated with IR is urolithiasis. The common feature of these two conditions is metabolic acidosis and mild inflammation. A patient diagnosed with IR and urolithiasis is a big challenge for a dietitian. It is necessary to check a thorough dietary history, make an appropriate anthropometric measurement, plan a full-fledged diet, and carry out the correct nutritional treatment. It is also essential to conduct proper laboratory diagnostics to plan nutritional treatment, which is often a big challenge for dietitians. The diet’s basic assumptions are based on the appropriate selection of carbohydrates, healthy fats, and wholesome protein sources. It is also essential to properly compose meals, prepare them, and plan physical activities tailored to the abilities. The study aims to summarise the necessary information on IR with concomitant urolithiasis, which may be helpful in dietary practice.

Analysis of potential risk factors associated with urolithiasis

OBJECTIVES

Eating habits, regular fluid intake, lifestyle and body composition are a primary point of research. The research focused on urolithiasis approaching potential danger, trying to interpret risk factors responsible for urolithiasis and disease recurrence.

METHODS

Research file contains 166 patients suffering from urolithiasis, 87 (52.4%) males and 79 (47.6%) females, and 172 healthy subjects from control group. All data was accessed using fully anonymous and confidential questionnaires, then evaluated in the statistical GNU PSPP 1.4 software.

RESULTS

More than 3/4 patients have a BMI higher than 24.9 and almost 40% of subjects have obesity class I, II, or III. Patients have higher BMI than subjects (d = 1.285; p < 0.001), and females have significantly higher BMI than males (d = 0.385; p = 0.007). Female patients have higher BMI than Slovak healthy females (p < 0.001; MD = 4.581; CI: 3.24-5.93). Patients have a lower daily water intake than subjects (φc = 0.157; p = 0.04) and more than ²/3 of patients have insufficient water intake. Sedentary employment prevails markedly in patients than in subjects. Patients are much less physically active than subjects (φc = 0.633; p < 0.001) and the difference is rising with increasing age of patients (ρ = - 0.232; p = 0.003). Low physical and working activity are characteristic for patients in this study. Patients smoke more often in comparison to subjects (φc = 0.261; p < 0.001). Patients consume more meats (red and white), cocoa and lentils. A lot of patients exceed recommended daily intake of pork and beef.

CONCLUSIONS

Many conditions are different for the healthy population and patients' group. High BMI, low fluid intake, exceeded red meat consumption, and low physical activity are the strongest factors for developing urolithiasis. Patients should consume more fluids daily, exercise frequently and vigorously, and lower amount of red meat consumed.

Effects of metabolic syndrome on renal stone progression

PURPOSE

Studies on howmetabolic syndrome affects renal stone progression in untreated asymptomatic patients are lacking. Therefore, we investigated the effect of metabolic syndrome on changes in renal stone size.

MATERIALS AND METHODS

We retrospectively analyzed 820 patients with renal stones incidentally detected on CT during regular health examinations and who underwent follow-up CT evaluations for > 1 year. The patients were divided into two groups according to the presence of metabolic syndrome. Changes in stone size during the follow-up were assessed, and differences were compared according to various factors. Predictors of stone size change on CT were assessed using linear regression analysis.

RESULTS

Overall, 820 asymptomatic patients without a history of stone treatments and with a mean follow-up of 52.4 months were included. Of these, 104 (12.7%) had metabolic syndrome and 335 (40.9%) showed stone size increase during the follow-up. The stone size at diagnosis was not significantly different between patients with and without metabolic syndrome (225.3 ± 332.6 vs. 183.9 ± 310.2 mm³, p = 0.159); however, a significant difference was observed in the change in stone size at follow-up (148.5 ± 352.0 vs. 81.5 ± 222.4 mm³, p = 0.001). Multivariable analysis showed that age (β = - 0.11; - 5.92 to -0.69; p = 0.013), fasting glucose level ≥ 100 mg/dl (β = 0.11; 9.78-99.73; p = 0.017), and metabolic syndrome (β = 0.10; 9.78-99.73; p = 0.017) were factors predictive of stone size changes.

CONCLUSION

Metabolic syndrome, fasting glucose level ≥ 100 mg/dl and young age are positively related to renal stone size changes. Therefore, periodic follow-up and metabolic syndrome management are required in asymptomatic patients with renal stones, especially in young age.

Why is diagnosis, investigation and improved management of kidney stone disease important? Non-pharmacological and pharmacological treatments for nephrolithiasis

INTRODUCTION

Progress in the medical treatment and management of nephrolithiasis has been limited to date and continues to depend on urinary metabolic screening to assess excretion of the main stone constituents, factors determining stone solubility and precipitation, and on dietary and lifestyle recommendations.

AREAS COVERED

In this review, we try to highlight some of the broader aspects of kidney stone disease in relation to recent epidemiological and pathophysiological findings, and emerging new treatments. Specifically, this review will cover recent evidence on the association between metabolic risk factors and kidney stone disease, dietary risk factors and dietary interventions to prevent kidney stones, and how genomics, metabolomics and proteomics may improve diagnosis and treatment of this troublesome, if rarely fatal, condition. PubMed was used to identify the most suitable references according to our search strategy; only full manuscripts were included.

EXPERT OPINION

What is emerging is that kidney stone disease is not an isolated disorder, but is systemic in nature with links to important and common co-morbidities such as diabetes, hypertension, cardiovascular disease, and chronic kidney disease. These associations support the need to take nephrolithiasis seriously as a medical condition and to adopt a more holistic approach to its investigation and treatment.

The impacts of metabolic syndrome on the risk of severe urolithiasis

Metabolic syndrome (MetS) is significantly correlated with urolithiasis. However, few studies have evaluated the severity of urolithiasis. This study aimed to investigate the relationship of MetS with severe urolithiasis disease (SUD). The data of 910 patients with urolithiasis in the Department of Urology, Second Hospital of Tianjin Medical University from June 2020 to May 2021 were retrospectively collected. The patients were divided into two groups according to the severity of urolithiasis, and the relationships of MetS and its components with SUD were evaluated. The results showed 605 SUD and 272 Mets patients. Multiple regression analysis showed that middle age, male gender, and MetS increased the risk of SUD, whereas serum magnesium decreased it (P < 0.05). Further analysis revealed that the odds ratio (OR) of SUD increased with MetS grade (0-4) (1.029-2.117). Grade 4 patients had a 2.1-fold higher risk of SUD than grade 0 patients (OR 2.117; 95% CI 1.053-4.256; P = 0.035); hypertension and dyslipidemia were most strongly associated with SUD among the four MetS features (P < 0.05). Additionally, calcium oxalate was the most predominant stone component (78.7%) in the SUD(+) group, which also had stones with higher uric acid and lower calcium oxalate dihydrate levels than those of the SUD(-) group (P < 0.05). Our study concluded that SUD is more common in middle-aged men, MetS is an independent risk factor for SUD. The more severe the MetS, the higher the risk of SUD, in which hypertension and dyslipidemia play major roles.

Risk factors for kidney stone disease recurrence: a comprehensive meta-analysis

Background

Kidney stone disease (KSD) is a common illness that causes an economic burden globally. It is easy for patients to relapse once they have suffered from this disease. The reported recurrence rate of KSD ranged from 6.1% to 66.9%. We performed this meta-analysis to identify various potential risk factors for the recurrence of KSD.

Methods

The PubMed, Embase and Web of Science databases were searched using suitable keywords from inception to Mar 2022. A total of 2,663 records were collected initially. After screening the literature according to the inclusion and exclusion criteria, 53 articles (40 retrospective studies; 13 prospective studies) including 488,130 patients were enrolled. The study protocol was registered with PROSPERO (No. CRD42020171771).

Results

The pooled results indicated that 12 risk factors including younger age (n = 18), higher BMI (n = 16), family history of kidney stones (n = 12), personal history of kidney stones (n = 11), hypertension (n = 5), uric acid stone (n = 4), race of Caucasian (n = 3), suspected kidney stone episode before the first confirmed stone episode (n = 3), surgery (n = 3), any concurrent asymptomatic (nonobstructing) stone (n = 2), pelvic or lower pole kidney stone (n = 2), and 24 h urine test completion (n = 2) were identified to be associated with KSD recurrence. In the subgroup analysis, patients with higher BMI (OR = 1.062), personal history of nephrolithiasis (OR = 1.402), or surgery (OR = 3.178) had a higher risk of radiographic KSD recurrence.

Conclusions

We identified 12 risk factors related to the recurrence of KSD. The results of this analysis could serve to construct recurrence prediction models. It could also supply a basis for preventing the recurrence of KSD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12894-022-01017-4.

Dyslipidemia Increases the Risk of Incident Kidney Stone Disease in a Large Taiwanese Population Follow-Up Study

The prevalence and incidence rates of kidney stone disease (KSD) in Taiwan are high; however, the association between lipid profile and KSD has yet to be investigated. The aim of this longitudinal study was to investigate the association between lipid profile with baseline and incident KSD in a large Taiwanese cohort. A total of 27,002 people enrolled in the Taiwan Biobank (TWB) were followed for a median of 4 years and classified into two groups according to whether they had (n = 1813; 6.7%) or did not have (n = 25,189; 93.3%) KSD at baseline. The presence of KSD was defined according to a self-reported history of kidney stones. The participants with baseline KSD (n = 1813) were excluded from the follow-up study, and the remaining participants were classified into two groups consisting of those who had (n = 640; 2.5%) or did not have (n = 24,549; 97.5%) incident KSD. After multivariable analysis, compared to quartile 1 of lipid profile, the participants in quartile 4 of triglycerides, quartiles 3 and 4 of high-density lipoprotein cholesterol (HDL-C), and quartile 4 of total cholesterol (Chol)/HDL-C ratio were significantly associated with baseline KSD. In the follow-up study, the participants in quartiles 2, 3, and 4 of triglycerides; quartile 2 of Chol; quartile 4 of HDL-C; quartile 3 of LDL-C; and quartiles 3 and 4 of Chol/HDL-C ratio were significantly associated with incident KSD. Our results showed that hypertriglyceridemia (67−93 mg/dL) was associated with a 1.463-fold increased risk of incident KSD and that low HDL-C (>63 mg/dL) protected against incident KSD formation. In addition, a Chol/HDL-C ratio larger than 3.64 was associated with a 1.381-fold increased risk of incident KSD. Our findings may imply that the optimal management of dyslipidemia may be associated with a lower risk of developing kidney stones.

Atorvastatin Decreases Renal Calcium Oxalate Stone Deposits by Enhancing Renal Osteopontin Expression in Hyperoxaluric Stone-Forming Rats Fed a High-Fat Diet

Calcium oxalate (CaOx) is the major constituent of kidney stones. Growing evidence shows a close connection between hyperlipidemia, cardiovascular disease (CVD), and the formation of kidney stones. Owing to their antioxidant properties, statins control hyperlipidemia and may ameliorate CaOx stone formation. The present study was designed to investigate the suppressive effects of statins on CaOx urolithiasis and their potential mechanism. We used rats fed a high-fat diet (HFD) to achieve hyperlipidemia (HL) and hydroxyproline (HP) water to establish a hyperoxaluric CaOx nephrolithiasis model; the animals were administered statins (A) for 28 days. The rats were divided into eight groups treated or not with A, i.e., Control, HP, HL, HL + HP. HL aggravated urinary calcium crystallization compared to the control. Due to increased expression of renal osteopontin (OPN), a key anti-lithic protein, and reduced free radical production, the calcium crystals in the urinary bladder increased as renal calcium deposition decreased. The levels of the ion activity product of CaOx (AP(CaOx)) decreased after statins administration, and AP(Calcium phosphate) (CaP) increased, which suggested the dominant calcium crystal composition changed from CaOx to CaP after statin administration. In conclusion, atorvastatin decreases renal CaOx stone deposits by restoring OPN expression in hyperoxaluric rats fed a HFD.

Sex Differences and the Risk of Kidney Stones

A significant increase in the prevalence of kidney stones has been observed worldwide. In the past decades, this expansion was more pronounced among women than men. The precise mechanisms involved in the differences in the risk profile of stone disease between men and women have not been fully elucidated. Diet and lifestyle only partially can explain the differences, and the combination of factors such as the influence of sex hormones, genetics, and disorders in acid-base handling and urine pH, as well as differences in calcium tubular reabsorption and stone composition in men and women, may contribute to differences in the risk profile. In this review, we summarize the sex differences in the pathophysiologic basis of kidney stones, which may contribute to a more focused approach.

Insights into the cytoprotective potential of Bergenia ligulata against oxalate-induced oxidative stress and epithelial-mesenchymal transition (EMT) via TGFβ1/p38MAPK pathway in human renal epithelial cells

Oxalate exposure to human renal epithelial cells triggers a vicious cycle of oxidative stress leading to cellular injury and deposition of calcium oxalate crystals on the injured cells. This results in further oxidative damage causing inflammation and loss of cell-cell adhesion factors, ultimately leading to irreparable kidney damage. However, these events can be attenuated or prevented by plants rich in antioxidants used in the traditional system of medicine for treatment of kidney stones. To delineate the mechanism by which Bergenia ligulata extract exerts its cytoprotective role in oxalate-induced injury we designed this study. Our results revealed that oxalate-injured HK2 cells cotreated with ethanolic extract of Bergenia ligulata displayed increased viability, reduced oxidative stress due to lowered production of intracellular reactive oxygen species (ROS) and decreased apoptosis. We also observed lowered markers of inflammation, along with increased expression of epithelial marker E-cadherin and decreased expression of mesenchymal markers Vimentin, F-actin, Transforming growth factor beta 1 (TGF-β1) and EMT-related proteins in renal tubular epithelial cells through immunocytochemistry, real-time PCR and western blotting. Our findings collectively suggest that by reducing oxidative stress, modulating crystal structure and preventing crystal-cell adhesion, B. ligulata inhibits the EMT pathway by downregulating the various mediators and thereby exerts its cytoprotective effect.

Effect of obesity and metabolic health on urolithiasis: A nationwide population-based study

Purpose

To investigate the risk of symptomatic urolithiasis requiring surgical treatment according to obesity and metabolic health status using a nationwide dataset of the Korean population.

Materials and Methods

Of the 5,300,646 persons who underwent health examinations between the year 2009 and 2016, within one year after the health examination, 35,137 patients who underwent surgical treatment for urolithiasis were enrolled. Participants were classified as “obese” or “non-obese” using a body mass index (BMI) cutoff of 25 kg/m². People who developed ≥1 metabolic disease component in the index year were considered “metabolically unhealthy”, while those with none were considered “metabolically healthy”.

Results

Out of 34,330 participants excluding 843 missing, 16,509 (48.1%), 4,320 (12.6%), 6,456 (18.8%), and 7,045 (20.5%) subjects were classified into the metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO) group, respectively. Mean BMI was 22.1±1.9 kg/m², 22.9±1.6 kg/m², 26.9±1.8 kg/m², and 27.9±2.4 kg/m² respectively. After adjusting the age and sex, the subjects in the MUNO group had an HR (95% CI) of 1.192 (1.120–1.268), those in the MHO group, 1.242 (1.183–1.305), and those in the MUO group, 1.341 (1.278–1.407) for either extracorporeal shockwave lithotripsy or surgery, compared to those in the MHNO group.

Conclusions

Metabolically healthy, obese individuals have a higher risk of developing symptomatic urolithiasis than non-obese, unhealthy, but have a lower risk than obese, unhealthy. It suggests that metabolic health and obesity have collaborative effects, independently affecting the development of symptomatic urinary stone diseases.

Association between hyperlipidemia and calcium oxalate lower urinary tract uroliths in dogs

Background

Metabolic syndrome is associated with formation of calcium oxalate (CaOx) uroliths in humans.

Objectives

To investigate the association between obesity and hyperlipidemia with CaOx lower urinary tract uroliths in client‐owned dogs.

Animals

Dogs with (n = 55, U [uroliths]‐dogs) and without (n = 39, UF [uroliths‐free]‐dogs) CaOx lower urinary tract uroliths.

Methods

Case‐control study. U‐dogs were retrospectively enrolled and compared to UF‐dogs. Body condition score (BCS; 1‐9 scoring scale), serum triglyceride (TG) and total cholesterol (CH) concentrations and glycemia (after >12‐hour food withholding) were recorded in both groups.

Results

On univariate logistic regression, when excluding Miniature Schnauzers, odds of having uroliths increased by a factor of 3.32 (95% CI 1.38‐11.12) for each mmol/L of TG (P = .027), of 39 (95% CI 9.27‐293.22) for each mmol/L of glycemia (P < .0001), and of 2.43 (95% CI 1.45‐4.45) per unit of BCS (P = .002). In multivariable models, the effect of TG was retained when all breeds were included for analysis and odds of having uroliths increased by a factor of 4.34 per mmol/L of TG (95% CI 1.45‐19.99; P = .02).

Conclusions and Clinical Importance

Serum lipid screening in dogs diagnosed with CaOx uroliths might be recommended to improve their medical staging and management.

Effect of Aegle marmelos on the growth of brushite crystals

Background

The urinary stone formation is a very common health problem due to the prolonged medication. Calcium Hydrogen Phosphate Dihydrate (CaHPO4.2H2O, CHPD and Brushite) is one of the major constituent of urinary stone crystals. The formation and deposition of brushite crystals is the central cause of recurrent kidney stone disease among the global population. The present study aims to investigate the effect of Aegle marmelos leaves on the growth of brushite crystals to explicate the inhibitory effect of urinary stones from a different point of view.

Methods

The CHPD crystals were grown by the Single Diffusion Gel growth technique. In order to inhibit the formation of urinary stones, CHPD crystals are grown in the laboratory in the pure form and by adding the prolonged medicine A. marmelos taken especially by diabetic patients. A comparative study of the pure and A. marmelos leaves added crystals has been carried out using the Growth factor, Powder X-ray diffraction, Microstructural parameters, FTIR and SEM-EDAX.

Results

Total mass of the grown crystals is found to decrease with increasing concentrations of leaf extract of the A. marmelos. On comparing with undoped, crystalline size of the A. marmelos doped samples is reduced. Disappearance of absorption band and peak shift in the FTIR shows the incorporation of functional groups of A. marmelos. The morphology changes of the treated crystals are assessed in SEM.

Conclusions

The result shows that herbal extracts prepared from A. marmelos have good inhibitory effect on the growth of the brushite urinary stone crystals considered.

Metabolic Syndrome Increases the Risk of Kidney Stone Disease: A Cross-Sectional and Longitudinal Cohort Study

We aimed to examine the association between metabolic syndrome and the risk of kidney stone development in a large-scale community-based cohort. A total of 121,579 participants enrolled in the Taiwan Biobank were analyzed. They were divided into two groups on the basis of presence of metabolic syndrome. The presence of kidney stone disease was defined by self-reported history of kidney stones. The mean age of participants was 50 years old, and self-reported kidney stones were observed in 3446 (10%) and 4292 (5%) participants with metabolic syndrome and without metabolic syndrome, respectively. Higher prevalence of kidney stone disease was found in participants with metabolic syndrome compared to those without metabolic syndrome (odds ratio (OR), 1.32; 95% confidence interval (95% CI), 1.25 to 1.39). In addition, the risk of incident kidney stone development was analyzed in a longitudinal cohort of 25,263 participants without kidney stones at baseline during a mean follow-up of 47 months. Multivariable Cox regression analysis revealed that the risk for incident kidney stone disease was higher in participants with metabolic syndrome than those without metabolic syndrome (hazard ratio, 1.24; 95% CI, 1.04 to 1.49). Our study suggests that metabolic syndrome does increase the risk of kidney stones.

THE FUNCTIONAL STATE OF THE RENAL PARENCHYMA AFTER VARIOUS VIDEO ENDOSURGICAL METHODS OF TREATMENT OF PATIENTS WITH LARGE AND COMPLEX KIDNEY STONES

The work is based on the analysis of literature data devoted to the problem of preserving the functional state of the kidneys with various video endoscopic methods of surgical treatment of large and complex kidney stones. The purpose of the review is to highlight the likelihood of deterioration in the functional state of the kidneys in the postoperative period. A detailed analysis of postoperative outcomes in various minimally invasive methods of treatment of patients with large and complex kidney stones was carried out, with an overview of the possibility of using dynamic nephroscintigraphy as a method of objectively assessing the functional state of the kidneys.

Epigenomic and transcriptional profiling identifies impaired glyoxylate detoxification in NAFLD as a risk factor for hyperoxaluria

Epigenetic modifications (e.g. DNA methylation) in NAFLD and their contribution to disease progression and extrahepatic complications are poorly explored. Here, we use an integrated epigenome and transcriptome analysis of mouse NAFLD hepatocytes and identify alterations in glyoxylate metabolism, a pathway relevant in kidney damage via oxalate release-a harmful waste product and kidney stone-promoting factor. Downregulation and hypermethylation of alanine-glyoxylate aminotransferase (Agxt), which detoxifies glyoxylate, preventing excessive oxalate accumulation, is accompanied by increased oxalate formation after metabolism of the precursor hydroxyproline. Viral-mediated Agxt transfer or inhibiting hydroxyproline catabolism rescues excessive oxalate release. In human steatotic hepatocytes, AGXT is also downregulated and hypermethylated, and in NAFLD adolescents, steatosis severity correlates with urinary oxalate excretion. Thus, this work identifies a reduced capacity of the steatotic liver to detoxify glyoxylate, triggering elevated oxalate, and provides a mechanistic explanation for the increased risk of kidney stones and chronic kidney disease in NAFLD patients.

The new patterns of nephrolithiasis: What has been changing in the last millennium?

Nephrolithiasis has been increasing over the last millennium. Although early epidemiologic studies have shown that kidney stones were two to three times more frequent in males than in females, recent reports have suggested that this rate is decreasing. In parallel a dramatic increase of nephrolithiasis has also been observed among children and adolescents. Furthermore, epidemiologic studies have shown a strong association between metabolic syndrome (Mets) traits and kidney stone disease. Patients with hypertension have a higher risk of stone formation and stone formers are predisposed to develop hypertension compared to the general population. An incidence of nephrolithiasis greater than 75% has been shown in overweight and obese patients compared to those of normal weight. It has also been reported that a previous diagnosis of diabetes mellitus increases the risk of future nephrolithiasis. Additionally, an association between metabolic syndrome and uric acid stone formation has been clearly recognized. Furthermore, 24-h urinary metabolic abnormalities have been decreasing among patients with nephrolithiasis over the last decades. Finally, nephrolithiasis could cause chronic kidney disease (CKD) and end stage renal disease (ESRD), especially in women and overweight patients. According to these observations, a better understanding of these new features among stone former patients may be required. Hence, the recognition and the correction of metabolic disorders could help not only to reduce the primary disease, but also stone recurrence.

Macrophage Function in Calcium Oxalate Kidney Stone Formation: A Systematic Review of Literature

Background

The global prevalence and recurrence rate of kidney stones is very high. Recent studies of Randall plaques and urinary components in vivo, and in vitro including gene manipulation, have attempted to reveal the pathogenesis of kidney stones. However, the evidence remains insufficient to facilitate the development of novel curative therapies. The involvement of renal and peripheral macrophages in inflammatory processes offers promise that might lead to the development of therapeutic targets. The present systematic literature review aimed to determine current consensus about the functions of macrophages in renal crystal development and suppression, and to synthesize evidence to provide a basis for future immunotherapy.

Methods

We systematically reviewed the literature during February 2021 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Articles investigating the relationship between macrophages and urolithiasis, particularly calcium oxalate (CaOx) stones, were extracted from PubMed, MEDLINE, Embase, and Scopus. Study subjects, languages, and publication dates were unrestricted. Two authors searched and screened the publications.

Results

Although several studies have applied mixed modalities, we selected 10, 12, and seven (total, n = 29) of 380 articles that respectively described cultured cells, animal models, and human samples.

The investigative trend has shifted to macrophage phenotypes and signaling pathways, including micro (m)-RNAs since the discovery of macrophage involvement in kidney stones in 1999. Earlier studies of mice-associated macrophages with the acceleration and suppression of renal crystal formation. Later studies found that pro-inflammatory M1- and anti-inflammatory M2-macrophages are involved. Studies of human-derived and other macrophages in vitro and ex vivo showed that M2-macrophages (stimulated by CSF-1, IL-4, and IL-13) can phagocytose CaOx crystals, which suppresses stone development. The signaling mechanisms that promote M2-like macrophage polarization toward CaOx nephrocalcinosis, include the NLRP3, PPARγ-miR-23-Irf1/Pknox1, miR-93-TLR4/IRF1, and miR-185-5p/CSF1 pathways.

Proteomic findings have indicated that patients who form kidney stones mainly express M1-like macrophage-related proteins, which might be due to CaOx stimulation of the macrophage exosomal pathway.

Conclusions

This systematic review provides an update regarding the current status of macrophage involvement in CaOx nephrolithiasis. Targeting M2-like macrophage function might offer a therapeutic strategy with which to prevent stones via crystal phagocytosis.

Independent and interactive effects of kidney stone formation and conventional risk factors for chronic kidney disease: a follow-up study of Japanese men

PURPOSE

To assess the impact of interactions between kidney stone formation and conventional risk factors on incident chronic kidney disease (CKD).

METHODS

A total of 11,402 subjects (men 30-69 years of age, Japanese) without CKD at baseline were observed over an average period of 4 years. Cox proportional hazards regression models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) to determine the association between incident CKD, kidney stone formation, and conventional risk factors (diabetes mellitus, hypertension, overweight/obesity, dyslipidemia, and hyperuricemia/gout). We also examined the interactions of renal stones and the conventional risk factors for CKD.

RESULTS

In total, 2301 men (20.2%) developed incident CKD during the follow-up period. After multivariable adjustment, kidney stones were found to increase the risk of incident CKD (HR 1.16; 95% CI 1.03-1.32). Kidney stone formers with hypertension, dyslipidemia, or hyperuricemia/gout presented a greater risk for incident CKD than those who had either kidney stones or other risk factors. However, no significant interactions between kidney stones and other risk factors were found to increase CKD risk. On the other hand, a negative interactive effect between kidney stones and overweight/obesity was observed, leading to reversed risk of incident CKD in coexistence of both factors.

CONCLUSION

Kidney stones were linked to a higher risk for the development of CKD. However, no positive interactive effects were identified between renal stones and conventional risk factors on the risk of incident CKD.

Association between metabolic syndrome and calcium oxalate stone risk in Chinese individuals: a nomogram prediction model

Objective

This retrospective study explored the association between calcium oxalate (CaOx) stones and metabolic syndrome. It also developed and validated a nomogram to aid in the prediction of CaOx stones.

Methods

This case-control study enrolled 150 patients with CaOx stones and 635 individuals without urolithiasis from October 2016 to October 2018. Student’s t-test, the chi-squared test, and logistic univariate and multivariate regression analyses were used. A nomogram for prediction of CaOx stones was established based on independent associated factors. The concordance index and calibration curves were plotted to determine nomogram accuracy.

Results

Female sex, age ≥66 years, blood pressure (systolic pressure ≥130 mmHg and/or diastolic pressure ≥85 mmHg), and blood uric acid level independently influenced the risk of CaOx stones, according to multivariate logistic regression analysis; these factors were included in the nomogram. The concordance index was 0.701 (95% confidence interval: 0.658–0.737). The standard curve showed a robust fit with the calibrated predictive curve.

Conclusions

Female sex, age ≥66 years, elevated blood pressure, and blood uric acid level independently influenced the risk of CaOx stones. Our nomogram for the prediction of CaOx stones may provide a clinical basis for the assessment of CaOx stone and facilitate early prevention efforts.

Trends in the prevalence of kidney stones in the United States from 2007 to 2016

The overall prevalence of kidney stones (KS) in the US rose from 3.2% in 1980 to 10.1% in 2016, but the trends in important subgroups have not been reported. We examined the prevalence trends of KS in subgroups of age, sex and race in the US and identified relevant laboratory factors associated with a history of KS using National Health and Nutrition Examination Survey (NHANES) data. We conducted a cross-sectional study among 28,209 US adults aged ≥ 20 years old in the NHANES from 2007 to 2016. We calculated the prevalence of a self-reported history of KS by using weights and standardized to the 2010 US Census population. We also compared relevant laboratory values according to the history of KS. The prevalence of KS decreased from 8.7% in 2007-2008 to 7.2% in 2011-2012 but then increased to 9.0% in 2013-2014 and 10.1% in 2015-2016. However, the overall prevalence of KS increased over 2007-2016 (p-trend = 0.02). Prevalence of KS among men was higher than women. Among men aged 20-79, there were significant quadratic trends in the prevalence of KS. Whereas, the prevalence of KS increased as a linear trend among women aged 20-59 years over 2007-2016. There were no consistent trends in the prevalence of KS by race. The prevalence trend of KS among non-Hispanic whites was 9.8% from 2007 to 2010 then dropped to 7.9% in 2011-2012 and increased to 10.6% in 2013-2014 and 12.1% in 2015-2016. A similar trend was also observed among non-Hispanic blacks. Among Hispanic, the prevalence of KS was 7.6% in 2007-2008 and 7.4% in 2009-2010 and then fluctuated over the next several time periods. For non-Hispanic Asians, the range was 4.4-4.6%. Regarding relevant laboratory factors, after adjusting for sex, race, age, BMI, smoking status, alcohol drinking, history of diabetes and gout, urine albumin-creatinine ratio and serum osmolality were independently associated with the history of KS in women and men. In conclusion, there was substantial variability in KS prevalence across individual 2-year time periods. This variation of period-specific prevalence values emphasizes the importance of looking at long-term trends and using more than a single 2-year cycle in analyses to increase the precision of the estimate. However, there was an overall increase in the prevalence of KS over 2007-2016.

A high basal metabolic rate is an independent predictor of stone recurrence in obese patients

Purpose

Basal metabolic rate (BMR) is an indicator of overall body metabolism and may portend unique aberrations in urine physico-chemistry and stone recurrence. The present study examined the effect of predicted BMR on 24 hours urinary metabolic profiles and stone recurrence in obese stone patients.

Materials and Methods

Data from 308 obese patients (body mass index [BMI] ≥30 kg/m²) diagnosed with urinary stone disease between 2003 and 2015 were analyzed retrospectively. BMR was calculated using the Harris–Benedict equation, and patients were classified into two predicted BMR categories (<1,145 kcal/day, ≥1,145 kcal/day). Urinary metabolic parameters and risk of stone recurrence were compared between the two groups.

Results

The high BMR group was more likely to be younger and female, and to have a high BMI and lower incidence of diabetes than the low BMR group (each p<0.05). There was a positive correlation between BMR and 24 hours urinary sodium, uric acid, and phosphate excretion. The amounts of stone-forming constituents such as calcium and uric acid were significantly higher in the high BMR group. Kaplan–Meier estimates showed that the high BMR group had a significantly shorter stone recurrence-free period than the low BMR group (log-rank test, p<0.001). Multivariate Cox regression analyses revealed that predicted BMR was an independent factor of stone recurrence (hazard ratio, 2.759; 95% confidence interval, 1.413–5.386; p=0.003).

Conclusions

BMR may be an easily measured parameter that can be used to identify risk of stone recurrence in obese stone patients.

Effect of endothelial dysfunction on the pathogenesis of urolithiasis in patients with metabolic syndrome

OBJECTIVE

The aim of the present prospective clinical study was to investigate the possible effect of endothelial dysfunction in urolithiasis.

METHODS

The study included 92 patients older than 18 years. The patients were divided into 4 groups with 23 patients each as group 1: metabolic sydrome (MetS) (-) stone disease (SD) (-), group 2: MetS (-) SD (+), group 3: MetS (+) SD (-) and group 4: MetS (+) SD (+). C-reactive protein, homocysteine, uric acid, and creatinine levels were evaluated between the groups. Endothelial (dys)function was evaluated based on the brachial artery flow-mediated dilation (FMD) measurement.

RESULTS

The mean age was 41.9 ± 10.2 (range, 18-62) years. Mean FMD value was 15.9 ± 18.2% (range, 24.0-68.5%). A strong significant difference was found between group 1 and 2 (p < .001); group 1 and 3 (p < .001) and group 1 and 4 (p < .001) with regard to FMD.

CONCLUSION

These results suggest that endothelial dysfunction plays an important role in the pathogenesis of urolithiasis in patients with MetS.

Association of nephrolithiasis with the risk of cardiovascular diseases: a longitudinal follow-up study using a national health screening cohort

OBJECTIVES

The aim of this study was to explore the associations of stroke and ischaemic heart disease in patients with nephrolithiasis.

DESIGN

A longitudinal follow-up study.

SETTING

Data from the Korean National Health Insurance Service-Health Screening Cohort (2002-2013) were retrieved to identify the occurrence of nephrolithiasis.

PARTICIPANTS AND INTERVENTIONS

In total, 19 103 patients with nephrolithiasis were matched at a 1:4 ratio with control participants for age, sex, income and region of residence.

PRIMARY AND SECONDARY OUTCOME MEASURES

The occurrence of stroke and ischaemic heart disease was analysed in both patients with nephrolithiasis and control participants. The primary outcome was HRs of stroke and ischaemic heart disease in a stratified Cox proportional hazards model. Smoking, alcohol consumption, obesity and Charlson Comorbidity Index were adjusted for as covariates. Subgroup analyses according to age and sex were also performed.

RESULTS

Eight per cent (1615/19 103) of patients with nephrolithiasis and 7.2% (5476/76 412) of control participants had stroke. Nine per cent (1879/19 103) of patients with nephrolithiasis and 7.7% (5895/76 412) of control participants had ischaemic heart disease. Patients with nephrolithiasis had risks of stroke and ischaemic heart disease that were 1.18 times (95% CI=1.11 to 1.24) and 1.24 times (95% CI=1.18 to 1.31) those of the control participants, respectively. The age and sex subgroups showed consistent results.

CONCLUSIONS

Nephrolithiasis was associated with increased risks of stroke and ischaemic heart disease.

Urinary Stones and Risk of Coronary Heart Disease and Stroke: the Japan Public Health Center-Based Prospective Study

Aim: Evidence is lacking about whether urinary stones are associated with the subsequent risk of cardiovascular diseases. Herein, we investigated the association between history of urinary stones and the risk of coronary heart disease (CHD) and stroke among middle-aged Japanese.

Methods: This cohort study included 89,037 Japanese men and women (45–74 years) registered in the Japan Public Health Center-based prospective study. Cox proportional hazard models were used to calculate the hazard ratios (HRs) and their 95% confidence intervals (CIs) for incident CHD and stroke among Japanese adults with a self-reported history of urinary stones compared with those without it. The following covariates were included in the regression models: age, sex, area, body mass index, and histories of hypertension, diabetes, hyperlipidemia, smoking habit, alcohol intake, and physical activity.

Results: In total, 1.31% of Japanese adults reported a positive history of urinary stones. Throughout a median follow-up period of 12 years, 1.16% of Japanese adults developed CHD, and 4.96% developed stroke. No associations were detected between history of urinary stones and the risk of CHD (HR 1.04; 95% CI: 0.64–1.67), stroke (HR 0.92; 95% CI: 0.71–1.20), or total CVD (HR 0.95; 95% CI: 0.75–1.19). Younger urinary stone formers (45–59 years) tended to have a higher, though statistically insignificant, risk of CHD than older urinary stone formers (60–74 years): [(HR 1.15; 95% CI: 0.61–2.15) versus (HR 0.83; 95% CI: 0.40–1.76)], respectively.

Conclusion: The history of urinary stones was shown to be not associated with the risk of CVD among Japanese adults.

Low bone mineral density is a potential risk factor for symptom onset and related with hypocitraturia in urolithiasis patients: a single-center retrospective cohort study

Background

Patients with urolithiasis have a lower bone mineral density (BMD) than those without stones, suggesting a potential correlation between calcium stone formation and bone resorption disorders, including osteopenia and osteoporosis.

Methods

To investigate the influence of BMD on clinical outcomes in urolithiasis, we performed a single-center retrospective cohort study to analyze patients with urolithiasis who underwent both BMD examination and 24-h urine collection between 2006 and 2015. Data from the national cross-sectional surveillance of the Japanese Society on Urolithiasis Research in 2015 were utilized, and additional data related to urinary tract stones were obtained from medical records. The primary outcome was the development of stone-related symptoms and recurrences during follow-up. A total of 370 patients were included in this 10-year study period.

Results

Half of the patients had recurrent stones, and the two-thirds were symptomatic stone formers. While only 9% of patients had hypercalciuria, 27% and 55% had hyperoxaluria and hypocitraturia, respectively. There was a positive correlation between T-scores and urinary citrate excretion. Both univariate and multivariate analyses demonstrated that female sex was associated with recurrences (odds ratio = 0.44, p = 0.007), whereas a T-score < − 2.5 and hyperoxaluria were associated with symptoms (odds ratio = 2.59, p = 0.037; odds ratio = 0.45, p = 0.01; respectively).

Conclusion

These results revealed that low T-scores might cause symptoms in patients with urolithiasis, suggesting the importance of BMD examination for high-risk Japanese patients with urolithiasis having hypocitraturia.

CT-related parameters and Framingham score as predictors of spontaneous passage of ureteral stones ≤ 10 mm: results from a prospective, observational, multicenter study

To investigate the reliability of newly defined CT-related parameters and cardiovascular risk factors in groups adjusted for stone size and location to predict spontaneous stone passage (SP) of uncomplicated ureteral stones ≤ 10 mm. The data of 280 adult patients with solitary unilateral ureteral stones ≤ 10 mm in diameter in non-contrast computed tomography were prospectively recorded. All patients undergoing a four-week observation protocol with medical expulsive therapy using tamsulosin were divided into two groups according to SP or no SP. Demographic, clinical and radiological findings of these groups were recorded. Spontaneous stone passage was observed in 176 (62.9%) of the patients, whereas the SP rate was 57.6% for 118 upper ureteral stones and 66.7% for 162 lower ureteral stones. The SP rate was 13.3 times greater with ureteral wall thickness < 1.88 mm, 4.4 times greater with a ratio of ureter to stone diameter of < 1.24, 3.4 times greater with Framingham score of < 11.5%, 2 times greater with neutrophil lymphocyte ratio < 1.96, 1.9 times greater with ureteral diameter < 6.33 mm and 1.5 times greater with stone volume < 38.54 mm³. Lower levels of ureteral wall thickness, ratio of ureter to stone diameter, Framingham score, neutrophil lymphocyte ratio, ureteral diameter, stone volume and absence of hydronephrosis were found to be more successful predictors. We consider that the success rate can be increased by selection of the proper option (observation or active treatment) according to these predictors.

Urinary Calculi: A Microbiological and Biochemical Analysis at a Tertiary Care Hospital in Eastern Nepal

Background

The occurrence of urinary tract infection in presence of urolithiasis is frequently noted; however, microbial agents of urolithiasis and their antimicrobial susceptibility patterns remain underinvestigated. This study aimed to identify the microorganisms isolated from urine and stone matrices to determine their antimicrobial susceptibility, to find the association between the pathogens of urine and stone matrices, and to perform the biochemical analysis of stones.

Methods

A total of 88 cases of urolithiasis admitted for elective stone removal at Department of surgery, B.P. Koirala Institute of Health Sciences (BPKIHS), were enrolled. Preoperative urine culture and postoperative stone culture were performed. Isolation, identification, and AST were done by the standard microbiological technique. Further qualitative biochemical analysis of stones was also attempted.

Result

Among 88 stone formers recruited, culture of urine, whole stone, and nidus yielded the growth of bacteria 44, 32, and 30, respectively. Bacteria isolated from urine culture correlated with those from stone matrices with a sensitivity of 90%, specificity of 79.69%, PPV of 63.64%, and NPV of 95.45%. Escherichia coli (46.7%) was the most common bacteria followed by Klebsiella pneumoniae (16.7%) and Proteus mirabilis (13.3%) from urine and stone cultures. Almost all the uropathogens isolated were susceptible to commonly used antibiotics. Calcium oxalate (84.1%) was common biochemical constituent found in stone formers followed by calcium oxalate + phosphate (8%).

Conclusions

The association of microorganism isolated from urine and nidus culture was significant that can predict the source of infective stone; however, in some cases, microorganisms and the antimicrobial susceptibility pattern from urine and nidus were different. This study emphasizes the use of appropriate antimicrobial agents to prevent the regrowth of residual stones and minimize the risk of infectious complications after surgical removal of stones.