Association of serum soluble α‑klotho with risk of kidney stone disease: a population-based cross-sectional study

BACKGROUND

The aim of the study was to explore the association of serum soluble klotho with kidney stone disease (KSD) in the general population over the age of 40 years in the United States.

METHODS

We integrated the data in National Health and Nutrition Examination Survey from 2007 to 2016 years. The relationship between serum soluble α‑klotho and prevalence of KSD was analyzed by constructing weighted multivariable logistic regression model, restricted cubic spline (RCS) curve, and subgroup analyses.

RESULTS

In the study, a total of 13,722 individuals were included in our study. A U-shaped association between serum soluble klotho and the risk of KSD was shown by the RCS curve (P value for nonlinear < 0.05). In the full adjusted model, compared with the lowest quartile of serum soluble α‑klotho, the adjusted odd ratios (95% confidence intervals) for KSD across the quartiles were (0.999 (0.859, 1.164), 1.005 (0.858, 1.176), and 1.061 (0.911, 1.235)). Subgroup analyses also showed that the U-shaped association of serum soluble α‑klotho with KSD was found among subjects who were age < 60 years, female or male, with or without hypertension, and BMI ≥ 30 kg/m2.

CONCLUSIONS

Our findings suggested that serum klotho levels had a U-shaped correlation with risk of KSD. When the Klotho level is at 818.66 pg/mL, prevalence of KSD is lowest. Therefore, maintaining a certain level of serum soluble α‑klotho could prevent the occurrence of KSD.

Higher oxidative balance score is associated with lower kidney stone disease in US adults: a population-based cross-sectional study

PURPOSE

Oxidative balance stress (OBS) was an important indicator for assessing exposure to oxidative stress related to diet and lifestyle. The purpose of this study was to explore the relationship between OBS and kidney stone disease (KSD).

METHODS

Secondary dataset analysis was performed by the study from six survey cycles (2007-2018) in the National Health and Nutrition Examination Survey (NHANES). OBS was the exposure factor and ever had kidney stone (yes or no) was the outcome. Weighted univariate or multivariate logistic regression models were used to estimate the associations.

RESULTS

The prevalence of KSD among participants was 8.6%. OBS showed a significant negative correlation with KSD (OR: 0.98, 95% CI 0.96-0.999), 35% reduction in KSD in the highest OBS quartile compared to the lowest OBS quartile. Dietary OBS was significantly negatively correlated with KSD (OR: 0.98, 95% CI 0.96-0.9998), but not with lifestyle OBS. In addition, OBS had a negative correlation with KSD in females (OR: 0.97, 95% CI 0.94-0.996), non-diabetic participants (OR: 0.98, 95% CI 0.96-0.99), and hypertensive participants (OR: 0.96, 95% CI 0.93-0.99), but OBS was not observed to be associated with KSD in gout participants. Interestingly, this relationship existed in participants aged 30-60 years and a ratio of family income to poverty (PIR) of 1.3-3.5 (all P value < 0.05).

CONCLUSION

Our study revealed that OBS was negative associated with KSD, and high OBS might be a protective factor in KSD. Targeting one of the components of OBS might be beneficial.

Deficient butyrate metabolism in the intestinal microbiome is a potential risk factor for recurrent kidney stone disease

Intestinal microbiome dysbiosis is a known risk factor for recurrent kidney stone disease (KSD) with prior data suggesting a role for dysfunctional metabolic pathways other than those directly utilizing oxalate. To identify alternative mechanisms, the current study analyzed differences in the metabolic potential of intestinal microbiomes of patients (n = 17) and live-in controls (n = 17) and determined their relevance to increased risk for KSD using shotgun metagenomic sequencing. We found no differences in the abundance of genes associated with known oxalate degradation pathways, supporting the notion that dysfunction in other metabolic pathways plays a role in KSD. Further analysis showed decreased abundance of key enzymes involved in butyrate biosynthesis in patient intestinal microbiomes. Furthermore, de novo construction of microbial genomes showed that the majority of genes significantly enriched in non-stone formers are affiliated with Faecalibacterium prausnitzii, a major butyrate producer. Specifically pertaining to butyrate metabolism, the majority of abundant genes mapped back to F. prausnitzii, Alistipes spp., and Akkermansia muciniphila. No differences were observed in ascorbate or glyoxylate metabolic pathways. Collectively, these data suggest that impaired bacterial-associated butyrate metabolism may be an oxalate-independent mechanism that contributes to an increased risk for recurrent KSD. This indicates that the role of the intestinal microbiome in recurrent KSD is multi-factorial, which is representative of the highly intertwined metabolic nature of this complex environment. Future bacteria-based treatments must not be restricted to targeting only oxalate metabolism.

Identification of biomarkers and potential therapeutic targets of kidney stone disease using bioinformatics

PURPOSE

Kidney stone disease (KSD) is a common urological disease, but its pathogenesis remains unclear. In this study, we screened KSD-related hub genes using bioinformatic methods and predicted the related pathways and potential drug targets.

METHODS

The GSE75542 and GSE18160 datasets in the Gene Expression Omnibus (GEO) were selected to identify common differentially expressed genes (DEGs). We conducted Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses to identify enriched pathways. Finally, we constructed a hub gene-miRNA network and drug-DEG interaction network.

RESULTS

In total, 44 upregulated DEGs and 1 downregulated DEG were selected from the GEO datasets. Signaling pathways, such as leukocyte migration, chemokine activity, NF-κB, TNF, and IL-17, were identified in GO and KEGG. We identified 10 hub genes using Cytohubba. In addition, 21 miRNAs were predicted to regulate 4 or more hub genes, and 10 drugs targeted 2 or more DEGs. LCN2 expression was significantly different between the GEO datasets. Quantitative real-time polymerase chain reaction (qRT-PCR) analyses showed that seven hub gene expressions in HK-2 cells with CaOx treatment were significantly higher than those in the control group.

CONCLUSION

The 10 hub genes identified, especially LCN2, may be involved in kidney stone occurrence and development, and may provide new research targets for KSD diagnosis. Furthermore, KSD-related miRNAs may be targeted for the development of novel drugs for KSD treatment.

Differential expression of urease genes and ureolytic activity of uropathogenic Escherichia coli and Pseudomonas aeruginosa isolates in different nutritional conditions

Uropathogens have adaptation strategies to survive in the host urinary tract by efficiently utilizing and tolerating the urinary metabolites. Many uropathogens harbour the enzyme urease for the breakdown of urea and the enzymatic breakdown of urea increases the pH and facilitate the struvite crystallization. In this study, the differential urease activity of uropathogenic Escherichia coli and Pseudomonas aeruginosa strains was investigated under different nutritional conditions. The experiments included measurement of growth, pH, urease activity, NH4-N generation and urease gene (ureC) expression among the bacterial strains under different conditions. Further, the implications of urea breakdown on the struvite crystallization in vitro and biofilm formation were also assessed. The study included urease positive isolates and for comparison urease negative isolates were included. Compared to the urease negative strains the urease positive strains formed higher biofilms and motility. The urease positive P. aeruginosa showed significantly higher (p < 0.01) pH and urease activity (A557-A630) compared to E. coli under experimental conditions. Further, supplementation of glucose to the growth media significantly increased the urease activity in P. aeruginosa and in contrast, it was significantly lower in E. coli. The expression profile of urease gene (ureC) was significantly higher (p < 0.001) in P. aeruginosa compared to E. coli and was consistent with the biochemical results of the urease activity under the nutritional conditions. The differential urease activity under two nutritional conditions influenced the biogenic struvite crystallization. It correlated with the urease activity showing higher crystallization rate in P. aeruginosa compared to E. coli. The results highlight the differential urease activity in two common uropathogens under different nutritional conditions that may have significant role on the regulation of virulence, pathogenicity and in the kidney stone disease.

Opioid-free percutaneous nephrolithotomy: an initial experience

INTRODUCTION

The opioid epidemic in the United States is an ongoing public health crisis that is in part fueled by excessive prescribing by physicians. Percutaneous nephrolithotomy (PCNL) is a procedure that conventionally involves opioid prescriptions for adequate post-operative pain control. We aimed to evaluate the feasibility of a non-opioid pain regimen by evaluating post-operative outcomes in PCNL patients discharged without opioids.

MATERIALS AND METHODS

As a quality improvement measure to reduce opioid consumption our department began routinely prescribing oral ketorolac instead of oxycodone-acetaminophen for pain control after PCNL. We retrospectively compared patients undergoing PCNL who had received ketorolac prescriptions (NSAID) to those who received oxycodone-acetaminophen prescriptions (NARC). Demographic, operative, and post-operative factors were obtained and compared in both groups. Peri-operative factors and demographics were compared using either Chi-squared tests, Mann-Whitney U tests. Surgical outcomes were compared between the two groups using Chi-squared tests and Fisher's exact tests. Multivariate logistic regression analysis was performed to determine whether ketorolac use was an independent predictor of post-surgical pain-related encounters. Primary outcome was unplanned pain-related healthcare encounters inclusive of office phone calls, unscheduled office visits, and emergency department (ED) visits. Secondary outcome measures were non-pain-related healthcare encounters, hospital readmissions, pain-related rescue medications prescribed, and post-op complications.

RESULTS

There were similar demographics and peri-operative characteristics amongst patients in both cohorts. There was no significant difference identified between NSAID and NARC regarding unplanned pain-related encounters (8/70, 11.4% vs. 10/70, 14.3%, p = 0.614). However, NARC experienced more unplanned phone calls (42, 60% vs. 24, 34.3%, p = 0.004). Multivariate analysis revealed only prior stone surgery was predictive of pain-related encounters after PCNL (p = 0.035).

CONCLUSION

Our results show that there were no significant differences in pain-related encounters between those who received ketorolac and oxycodone-acetaminophen following PCNL. A non-opioid pathway may mitigate the potential risk associated with opioid prescription without compromising analgesia. Prospective comparative studies are warranted to confirm feasibility.

Causal effects of inflammatory bowel diseases on the risk of kidney stone disease: a two-sample bidirectional mendelian randomization

BACKGROUND

Existing epidemiological observational studies have suggested interesting but inconsistent clinical correlations between inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), and kidney stone disease (KSD). Herein, we implemented a two-sample bidirectional Mendelian randomization (MR) to investigate the causal relationship between IBD and KSD.

METHODS

Data on IBD and KSD were obtained from Genome-Wide Association Studies (GWAS) summary statistics and the FinnGen consortium, respectively. Strict selection steps were used to screen for eligible instrumental SNPs. We applied inverse variance weighting (IVW) with the fix-effects model as the major method. Several sensitivity analyses were used to evaluate pleiotropy and heterogeneity. Causal relationships between IBD and KSD were explored in two opposite directions. Furthermore, we carried out multivariable MR (MVMR) to obtain the direct causal effects of IBD on KSD.

RESULTS

Our results demonstrated that CD could increase the risk of KSD (IVW: OR = 1.06, 95% CI = 1.03-1.10, p < 0.001). Similar results were found in the validation group (IVW: OR = 1.05, 95% CI = 1.01-1.08, p = 0.013) and in the MVMR analysis. Meanwhile, no evidence of a causal association between UC and KSD was identified. The reverse MR analysis detected no causal association.

CONCLUSIONS

This MR study verified that CD plays a critical role in developing kidney stones and that the effect of UC on KSD needs to be further explored.

Mendelian randomization analysis reveals fresh fruit intake as a protective factor for urolithiasis

OBJECTIVE

Previous studies have proposed that food intakes are associated with the risk of urolithiasis. Here, we conducted a two-sample Mendelian randomization (MR) study to evaluate the causal effects of different food intakes on urolithiasis.

METHODS

Independent genetic variants associated with different food intakes at a genome-wide significant level were selected from summary-level statistics of genome-wide association studies from the UK Biobank. The association of these instrumental variables with urolithiasis was studied in a cohort from FinnGen Consortium.

RESULTS

Among the 15 studied food intake exposures, tea intake (odds ratio [OR] = 0.433, 95% confidence interval [CI] = 0.281-0.667, p value = 1.470 × 10-4) and fresh fruit intake (OR = 0.358, 95% CI = 0.185-0.694, p value = 0.002) were found to significantly reduce the risk of the calculus of kidney and ureter. The association remained consistent in the sensitivity analyses. After adjusting for the effects of vitamin D and vitamin C, fresh fruit intake remained the reverse causal association with the calculus of kidney and ureter.

CONCLUSIONS

Genetically proxied fresh fruit intake is causally associated with a reduced risk of the calculus of kidney and ureter.

Atypical clinical presentation and management of urinary stone disease in non-verbal non-ambulatory children

INTRODUCTION

Management of kidney stones primarily depends on various factors such as the presence of urinary tract obstruction, pain, stone size, location, impact on renal function, and the existence of infection. Renal colic is the classic presentation of an obstructive kidney stone. However, in this study, we present a cohort of non-verbal non-ambulatory (NVNA) patients who exhibit a distinct and uncommon presentation of kidney stones due to their medical conditions. Information about kidney stone disease in this gropup of complex pediatric patients is, scarce and their associated risk factors are not well understood. Therefore, we aim to summarize the clinical presentation, and management challenges in this unique group of NVNA patients to identify potential variables for prospective studies.

METHODS

A retrospective chart review was completed for all NVNA patients seen at the pediatric multidisciplinary kidney stone clinic between July 2020 to August 2022. Demographic variables, clinical presentation data, metabolic evaluation, radiological imaging, and surgical management was included for analysis.

RESULTS

A total of 224 pediatric patients were referred to the multidisciplinary stone clinic. Of those, 27 were identified to be NVNA. The most common primary diagnosis was Cerebral Palsy followed by Lennox-Gastaut syndrome. Average age at first kidney stone presentation was 11.5 years ± 5.7 years. An obstructing stone was diagnosed in 18 (66%) patients, 4 (22.2%) of these presented with sepsis. Average stone burden was 9.2 mm ( ± 5.8 mm). Of the obstructing stones, 13 (72%) were in the kidney. All patients with an obstructing stone underwent surgical management with retrograde endoscopic approach. Metabolic 24-h-urine analysis was completed in 24 (89%) patients. 17 (62%) had an elevated urine density, 15 (55%) demonstrated calcium oxalate supersaturation, 12 (44%) met criteria for acidosis, and 7 (26%) had significant hypocitraturia.

DISCUSSION

NVNA patients represent a unique cohort whose clinical presentation is atypical. Limited ability to express symptoms makes early detection difficult to recognize. Twenty two percent of patients present with sepsis as their first manifestation of an acutely obstructing kidney stone. Pain is subjectively interpreted by caregivers and is an uncommon symptom. Our cohort demonstrates common risk factors for stones including propensity for chronic dehydration, slow urinary tract transit, ineffective bladder emptying, G-tube feeding, and lithogenic medications.

CONCLUSION

NVNA pediatric patients have atypical kidney stone clinical presentation. Awareness of this unique group of patients should support future collaborative studies to focus on understanding these atypical presentations and reflect on improving management.

Prognostic value of total body muscle-fat ratio in patients with kidney stone disease: A US population-based study

Purpose

To examine the relationship between the muscle-fat ratio (MFR) and kidney stone disease (KSD) in the adult population of the United States between 2011 and 2018, and whether it can be used as a predictor of KSD prognosis.

Materials and methods

We conducted a cross-sectional study analysing 9326 patients from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2018. We analyzed all participants by sex, age, race, level of education, marital status, household income-to-poverty ratio, hypertension, diabetes, vigorous physical activity, moderate physical activity, blood urea nitrogen, creatinine, uric acid, cotinine, and MFR. Dose-response curves with a restricted cubic spline function, univariate and multifactorial logistic regression were used for the analysis of the correlation between MFR and KSD. Finally, we created predictive models based on age, race, hypertension, diabetes mellitus, cotinine and MFR. The prediction model was evaluated using calibration curves, receiver operating characteristic curves and clinical decision curves from the training and test sets.

Results

Of the 9326 participants, 8582 (92%) self-reported that they did not have KSD and 744 (8%) self-reported that they had KSD. Univariate and multifactorial logistic regression showed that MFR was negatively associated with the prevalence of KSD (odds ratio [OR]: 0.770, 95% CI: 0.703-0.843; OR: 0.815, 95% CI: 0.738-0.897). Similarly, the risk of developing KSD decreased with increasing MFR as shown by the dose curves in the restricted cubic bar graphs. Furthermore, there is some accuracy (AUC = 0.652) and clinical applicability to the model we constructed based on the results of multifactorial logistic regression.

Conclusion

The MFR is protective factor against the developing KSD in adults in the USA.

Association between hysterectomy and kidney stone disease: results from the National Health and Nutrition Examination Survey 2007-2018 and Mendelian randomization analysis

PURPOSE

Hysterectomy is one of the most common types of gynecological operations and it is associated with numerous postoperative complications. Few studies have reported a definitive association between hysterectomy and kidney stone disease (KSD). This study aimed to explore whether hysterectomy increases the risk of KSD.

METHODS

This is a cross-sectional study that used six continuous cycles of data obtained from the National Health and Nutrition Examination Survey from 2007 to 2018. The correlations between hysterectomy or age at hysterectomy and the prevalence of KSD were assessed using weighted multivariable-adjusted logistic regression. Further, five methods of two-sample Mendelian randomization (MR) were applied to decrease bias and infer causality in the observational study.

RESULTS

After adjusting for potential confounders, hysterectomy (OR: 1.37, 95% CI 1.04-1.81) was found to be positively associated with the prevalence of KSD, whereas age at hysterectomy was found to be negatively associated with the prevalence of KSD (OR: 0.96, 95% CI: 0.94-0.98). In the inverse-variance weighted method, MR analyses suggested that genetically predicted hysterectomy is causally associated with a higher risk of KSD (OR: 11.961, 95% CI 1.12-1.28E2).

CONCLUSIONS

Hysterectomy could increase the risk of KSD. Younger age at hysterectomy is associated with a higher risk of KSD. Further prospective cohort studies with larger sample sizes and longer follow-up times are needed.

Development of convenient crystallization inhibition assays for structure-activity relationship studies in the discovery of crystallization inhibitors

Kidney stone diseases are increasing globally in prevalence and recurrence rates, indicating an urgent medical need for developing new therapies that can prevent stone formation. One approach we have been working on is to develop small molecule inhibitors that can interfere with the crystallization process of the chemical substances that form the stones. For these drug discovery efforts, it is critical to have available easily accessible assay methods to evaluate the potential inhibitors and rank them for structure-activity relationship studies. Herein, we report a convenient, medium-to-high throughput assay platform using, as an example, the screening and evaluation of inhibitors of L-cystine crystallization for the prevention of kidney stones in cystinuria. The assay involves preparing a supersaturated solution, followed by incubating small volumes (<1 mL) of the supersaturated solution with test inhibitors for 72 hours, and finally measuring L-cystine concentrations in the supernatants after centrifugation using either a colorimetric or fluorometric method. Compared to traditional techniques for studying crystallization inhibitors, this miniaturized multi-well assay format is simple to implement, cost-effective, and widely applicable in determining and distinguishing the activities of compounds that inhibit crystallization. This assay has been successfully employed to discover L-cystine diamides as highly potent inhibitors of L-cystine crystallization such as LH708 with an EC50 of 0.058 μM, 70-fold more potent than L-CDME (EC50 = 4.31 μM).

The impact of secondhand smoke on the development of kidney stone disease is not inferior to that of smoking: a longitudinal cohort study

BACKGROUND

Tobacco use and secondhand smoke (SHS) are risk factors of kidney stone disease (KSD). The hypothesis is that tobacco produces chemicals that increase oxidative stress and vasopressin, which leads to decreased urine output, and contributes to stone formation. The aim of this study was to examine the effects of smoking and SHS on the development of KSD.

MATERIALS AND METHODS

We analyzed a total of 25,256 volunteers with no history of KSD participated in the Taiwan Biobank. The presence of underlying and follow-up KSD was surveyed by a self-administrated questionnaire. They were classified into three groups on the basis of smoking and SHS exposure, accessed with survey questionnaires; never-smokers with no SHS exposure, never-smokers with SHS exposure and ever-smokers groups.

RESULTS

KSD was noted in 352 (2.0%), 50 (3.3%) and 240 (4.1%) subjects in the never-smokers with no SHS exposure, never-smokers with SHS exposure and ever-smokers groups, respectively, with a mean follow-up of 4 years. The odds ratio (OR) of KSD was higher in the never-smokers with SHS exposure (OR, 1.622; 95% confidence interval [95% CI], 1.225 to 2.255) and ever-smokers groups (OR, 1.282; 95% CI, 1.044 to 1.574) than in the never-smokers with no SHS exposure group after adjustment of confounders. In addition, never-smokers with SHS exposure had similar effects on the development of KSD than ever-smokers (OR, 1.223; 95% CI, 0.852 to 1.756).

CONCLUSION

Our study suggests that both smoking and SHS are a risk factor for developing KSD and that the impact of SHS is not inferior to that of smoking.

TRIAL REGISTRATION

The study was conducted in accordance with the Declaration of Helsinki and approved by the Institutional Review Board of Kaohsiung Medical University Hospital (KMUHIRB-E(I)-20,210,058).

Kidney function may partially mediated the protective effect of urinary uromodulin on kidney stone

The causal links between urinary uromodulin (uUMOD) and kidney stone disease (KSD) are still not clarified in general population. We assessed their relationships combining 2-sample Mendelian randomization (MR) and multivariable (MVMR) designs among general population of European ancestry. The summary information for uUMOD indexed to creatinine levels (29,315 individuals) and KSD (395,044 individuals) were from 2 independent genome-wide association studies (GWAS). The primary causal effects of exposures on outcomes were evaluated using inverse variance-weighted (IVW) regression model. Multiple sensitivity analyses were also performed. In 2-sample MR, we found that 1-unit higher genetically predicted uUMOD levels were associated with a lower risk of KSD (OR = 0.62; 95% CI 0.55-0.71; P = 2.83E-13). In reverse, we did not find the effect of KSD on uUOMD using IVW (beta = 0.00; 95% CI - 0.06-0.05; P = 0.872) and other sensitivity analyses. In MVMR, uUMOD indexed to creatinine levels were directly associated with the risk of KSD after introducing eGFR, SBP, urinary sodium or all three factors (OR = 0.71; 95% CI 0.64-0.79; P = 1.57E-09). Furthermore, our study supported that the protective effect of uUMOD on KSD may be partially mediated by eGFR (beta = - 0.09; 95% CI - 0.13 to - 0.06; mediation proportion = 20%). Our study supported that the protective effect of genetically predicted higher uUMOD levels on KSD may be partially mediated by eGFR decline, but not via SBP or urinary sodium. uUMOD might be a treatment target in preventing KSD in general population.

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.

Shockwave Lithotripsy Complications According to Modified Clavien-Dindo Grading System. A Systematic Review and Meta-regression Analysis in a Sample of 115 Randomized Controlled Trials

CONTEXT

Shockwave lithotripsy (SWL) shows clear associated benefits for urolithiasis patients.

OBJECTIVE

To identify and classify SWL complications according to modified Clavien-Dindo grading system while assessing the effect of different patient characteristics, stone parameters, types of lithotripters, and lithotripsy techniques.

EVIDENCE ACQUISITION

Literature was reviewed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement.

EVIDENCE SYNTHESIS

We analyzed the results of 115 randomized trials including 17827 patients, of whom 16.06%, 2.07%, 2.23%, 1.32%, 0.85%, 0.16%, and 0% suffered from Clavien I, II, III, IIIa, IIIb, IV, and V complications, respectively. In total, 18.43% of patients suffered from Clavien I-II and 2.48% from Clavien III-IV complications. In studies with >100 treated patients, Clavien I, III, and IV complication rates and need for auxiliary procedure rates were lower than in studies with smaller sample size. Electrohydraulic lithotripters led to a higher rate of Clavien IIIb and IV complications than electromagnetic lithotripters. Clavien I-II complications were increased by 14.3% in patients with multiple and complicated stones. Hematuria was increased by 8.29% in patients who underwent intravenous urography preoperatively and had longer duration of SWL. Pain occurrence was increased by 14.79% in patients with more than one stone at the time of SWL and by 3.21% in those who were managed with a piezoelectric lithotripter.

CONCLUSIONS

SWL should not be considered an uneventful procedure, as in 2.5% of cases an intervention or Clavien III-V complication will be observed. Low-volume centers, treatment of multiple or complex stones, a long-lasting SWL session, and electrohydraulic lithotripters are associated with higher rates of complications.

PATIENT SUMMARY

We analyze the occurrence of shockwave lithotripsy (SWL) complications in 17000 patients. In centers with larger caseloads, complications were less common. The type of lithotripter is associated with complications. An increased number of treated stones, complex stones, and increased SWL duration were associated with a higher incidence of pain and hematuria.

Roles of heat-shock protein 90 and its four domains (N, LR, M and C) in calcium oxalate stone-forming processes

Human heat-shock protein 90 (HSP90) has four functional domains, including NH₂-terminal (N), charged linker region (LR), middle (M) and COOH-terminal (C) domains. In kidney stone disease (or nephrolithiasis/urolithiasis), HSP90 serves as a receptor for calcium oxalate monohydrate (COM), which is the most common crystal to form kidney stones. Nevertheless, roles of HSP90 and its four domains in kidney stone formation remained unclear and under-investigated. We thus examined and compared their effects on COM crystals during physical (crystallization, growth and aggregation) and biological (crystal–cell adhesion and crystal invasion through extracellular matrix (ECM)) pathogenic processes of kidney stone formation. The analyses revealed that full-length (FL) HSP90 obviously increased COM crystal size and abundance during crystallization and markedly promoted crystal growth, aggregation, adhesion onto renal cells and ECM invasion. Comparing among four individual domains, N and C domains exhibited the strongest promoting effects, whereas LR domain had the weakest promoting effects on COM crystals. In summary, our findings indicate that FL-HSP90 and its four domains (N, LR, M and C) promote COM crystallization, crystal growth, aggregation, adhesion onto renal cells and invasion through the ECM, all of which are the important physical and biological pathogenic processes of kidney stone formation.

The Use of Neutrophil Gelatinase-Associated Lipocalin (NGAL) as a Diagnostic and Prognostic Biomarker in Urinary Tract Obstruction: a Systematic Review

PURPOSE OF REVIEW

The early recognition of urinary tract obstruction (UTO) is vital in order to prevent mortality and morbidity associated with an acute kidney injury (AKI) and progression to irreversible kidney damage. Urinary biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL) have been recognised as an accurate tool in the timely diagnosis of AKI, but its role in the detection, prognosis and subsequent monitoring of a variety of obstructive uropathies has not yet been explored. We performed a systematic review of literature in accordance with Cochrane methodology from inception to August 2021.

RECENT FINDINGS

Eleven studies were included in which urine and serum NGAL were measured (616 patients) presenting with multiple UTO aetiologies. Four investigated kidney stone disease (KSD) exclusively, whilst other studies identified other causes of UTO including pelviureteric junction obstruction (PUJO), retroperitoneal fibrosis (RPF) and ureteric strictures. Six studies monitored NGAL levels after surgical intervention to relieve the obstruction. Nine studies demonstrated a significant increase in both urine and serum NGAL levels in UTO, often in a more sensitive and timely manner than serum creatinine. Subclinical unilateral UTO could be recognised by urinary NGAL levels even in the absence of changes in serum creatinine. Following surgical intervention, a reduction in urinary and serum NGAL was seen in all but two studies. NGAL levels decreased acutely by 14% in 2 h and showed a long-term reduction of 78% in 6 months. Readily available but not yet widely accepted, NGAL has the potential to be a less invasive, low-cost diagnostic test for urinary tract obstructions as a whole. Not only can it be used as a marker of treatment success but also to monitor for obstruction recurrence or progression. Further research is required to acknowledge urinary biomarkers such as NGAL as a potential replacement to standard renal function monitoring tests in the context of obstructive uropathy.

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.

Identification of the pivotal role of SPP1 in kidney stone disease based on multiple bioinformatics analysis

Background

Kidney stone disease (KSD) is a multifactorial disease involving both environmental and genetic factors, whose pathogenesis remains unclear. This study aims to explore the hub genes related to stone formation that could serve as potential therapeutic targets.

Methods

Based on the GSE73680 dataset with 62 samples, differentially expressed genes (DEGs) between Randall’s plaque (RP) tissues and normal tissues were screened and weighted gene co-expression network analysis (WGCNA) was applied to identify key modules associated with KSD. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were performed to explore the biological functions. The protein–protein interaction (PPI) network was constructed to identify hub genes. Meanwhile, CIBERSORT and ssGSEA analysis were used to estimate the infiltration level of the immune cells. The correlations between hub genes and immune infiltration levels were also investigated. Finally, the top hub gene was selected for further GSEA analysis.

Results

A total of 116 DEGs, including 73 up-regulated and 43 down-regulated genes, were screened in the dataset. The red module was identified as the key module correlated with KSD. 53 genes were obtained for functional enrichment analysis by taking the intersection of DEGs and genes in the red module. GO analysis showed that these genes were mainly involved in extracellular matrix organization (ECM) and extracellular structure organization, and others. KEGG analysis revealed that the pathways of aldosterone-regulated sodium reabsorption, cell adhesion molecules, arachidonic acid (AA) metabolism, and ECM-receptor interaction were enriched. Through PPI network construction, 30 hub genes were identified. CIBERSORT analysis revealed a significantly increased proportion of M0 macrophages, while ssGSEA revealed no significant differences. Among these hub genes, SPP1, LCN2, MMP7, MUC1, SCNN1A, CLU, SLP1, LAMC2, and CYSLTR2 were positively correlated with macrophages infiltration. GSEA analysis found that positive regulation of JNK activity was enriched in RP tissues with high SPP1 expression, while negative regulation of IL-1β production was enriched in the low-SPP1 subgroup.

Conclusions

There are 30 hub genes associated with KSD, among which SPP1 is the top hub gene with the most extensive links with other hub genes. SPP1 might play a pivotal role in the pathogenesis of KSD, which is expected to become a potential therapeutic target, while its interaction with macrophages in KSD needs further investigation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01157-4.

Genetics of kidney stone disease-Polygenic meets monogenic

Kidney stone disease comprising nephrolithiasis and nephrocalcinosis is a clinical syndrome of increasing prevalence with remarkable heterogeneity. Stone composition, age of manifestation, rate of recurrence, and impairment of kidney function varies with underlying etiologies. While calcium-based kidney stones account for the vast majority their etiology is still poorly understood. Recent studies underline the notion that genetic susceptibility together with dietary habits constitutes the major driver of kidney stone formation. In addition to single gene (Mendelian) disorders, which are most likely underestimated in the adult population, common risk alleles explain part of the observed heritability. Interestingly, identified GWAS loci often match those of Mendelian disease genes and vice versa (CASR, SLC34A1, CYP24A1). These findings provide mechanistic links related to renal calcium homeostasis, vitamin D metabolism, and CaSR-signaling regulated by the CaSR-CLDN14-CLDN16/19 axis (paracellular Ca²⁺ reabsorption) and TRPV5 (transcellular Ca²⁺ reabsorption). Recent identification of new single gene disorders of calcium-oxalate-nephrolithiasis (SLC26A1, CLDN2) and distal renal tubular acidosis with nephrocalcinosis (FOXI1, WDR72, ATP6V1C2) enabled additional insights into the kidney-gut axis and molecular prerequisites of proper urinary acidification. Implementation of centralized patient registries on hereditary kidney stone diseases are necessary to build up well characterized cohorts for urgently needed clinical studies.

A polymorphism in the 3'-untranslated region of the matrix metallopeptidase 9 gene is associated with susceptibility to idiopathic calcium nephrolithiasis in the Chinese population

Objective

To investigate whether single nucleotide polymorphisms (SNPs) in the 3′ untranslated region (UTR) of the matrix metallopeptidase 9 gene (MMP9) are associated with susceptibility to calcium oxalate stones.

Methods

A total of 428 patients with kidney stone disease (KSD) and 450 control individuals were enrolled. Three MMP9 SNPs (rs20544, rs9509, and rs1056628) were genotyped, and MMP9 mRNA and protein expression was determined in patients and controls. The dual luciferase reporter gene assay was conducted by transfecting HEK293 cells with miR-491-5p mimics and plasmids containing MMP9 with rs1056628 AA/CC genotypes.

Results

The rs1056628 CC genotype was significantly increased in KSD patients compared with controls (CC vs AA: odds ratio [OR] = 2.279, 95% confidence interval [CI] = 1.048–4.956). The rs1056628 C allele frequency was higher in KSD patients than controls. The increased KSD risks associated with rs1056628 were more evident in individuals aged <30 years (OR = 3.504, 95% CI = 1.102–11.139) and men (OR = 2.522, 95% CI = 1.004–6.334). mRNA and protein levels of MMP9 were significantly higher in KSD patients with the CC genotype than in those with the AA genotype.

Conclusion

This study demonstrates that MMP9 SNP rs1056628 is associated with a significant KSD risk in Chinese Han individuals.

Genetic Polymorphisms of RGS14 and Renal Stone Disease

BACKGROUND

Renal stone disease (RSD) is a common disease of the human urinary system and is regarded as a multifactorial condition affected by environmental and genetic factors. RGS14 encodes a complex scaffolding protein, known as regulator of G protein signaling 14, which is enriched in hippocampal area CA2 dendritic spines.

AIM OF THE STUDY

We aimed to investigate the association between genetic polymorphisms in RGS14 and the risk of RSD based on a large sample of the Chinese Han population.

METHODS

A total of 1,436 subjects, comprising 506 patients with RSD and 920 controls, were enrolled in the study. Ten tag SNPs located in the RGS14 gene region were chosen for genotyping. Genetic associations were evaluated at both the single marker and haplotype levels. Genotypic (χ² test) and allelic analyses (Cochran-Armitage test for trend) were performed for single marker-based association. Two bioinformatics tools, RegulomeDB and GTEx, were used to examine the functional consequences of the target SNP.

RESULTS

SNP rs11746443 was found to be significantly associated with disease status (χ² = 12.60, p = 0.0018). Moreover, the A allele of this SNP was significantly associated with an increased risk of RSD (OR [95%CI] = 1.36 [1.13-1.65]). Multiple significant eQTL signals of rs11746443 on RGS14 were identified.

CONCLUSIONS

This study replicated the association signal of RGS14 with RSD in a large sample of the Chinese Han population. The results suggest that the SNP rs11746443 of RGS14 might increase the risk of RSD by regulating the Ca²⁺ levels in humans.

Characteristics of the urinary microbiome in kidney stone patients with hypertension

Background

Kidney stone disease (KSD) is more common in individuals with hypertension (HTN) than in individuals with normotension (NTN). Urinary dysbiosis is associated with urinary tract disease and systemic diseases. However, the role of the urinary microbiome in KSD complicated with HTN remains unclear.

Methods

This study investigated the relationship between the pelvis urinary microbiome and blood pressure (BP) in patients with KSD co-occurring with HTN (KSD-HTN) and healthy controls (HC) by conducting 16S rRNA gene sequencing of bacteria in urine samples. The urine samples were collected (after bladder disinfection) from 50 patients with unilateral kidney calcium stones and NTN (n = 12), prehypertension (pHTN; n = 11), or HTN (n = 27), along with 12 HCs.

Results

Principal coordinates analysis showed that there were significant differences in the urinary microbiomes not only between KSD patients and HCs but also between KSD-pHTN or KSD-HTN patients and KSD-NTN patients. Gardnerella dominated in HCs, Staphylococcus dominated in KSD-NTN patients and Sphingomonas dominated in both KSD-pHTN and KSD-HTN patients. The abundance of several genera including Acidovorax, Gardnerella and Lactobacillus was correlated with BP. Adherens junction and nitrogen and nucleotide metabolism pathways, among others, were associated with changes in BP.

Conclusions

The findings suggest that patients with KSD complicated with HTN have a unique urinary microbiome profile and that changes in the microbiome may reflect disease progression and may be useful to monitor response to treatments.

miRNA-34a inhibits cell adhesion by targeting CD44 in human renal epithelial cells: implications for renal stone disease

Nephrolithiasis is a very common disease in which cell-crystal adhesion is an essential mechanism for kidney stone formation. This study has explored the anti-adhesion function of the microRNA, miR-34a, by targeting CD44, a cell surface receptor, in human renal epithelial (HK-2) cells. The expression of CD44 was monitored by qPCR and western blot. A luciferase assay validated the target of miR-34a in CD44 3' UTR. Immunofluorescence staining under confocal microscopy was used to detect the cell-crystal adhesion effects in vitro. Pizzolato staining was performed to examine the adhesion role of miR-34a in vivo. In HK-2 cells, miR-34a was down-regulated and CD44 was up-regulated when exposed to calcium oxalate monohydrate crystals. Moreover, miR-34a negatively regulated the expression of CD44. According to the luciferase report assay, miR-34a direct targeted a binding site in the CD44 3'UTR. In vitro experiments, miR-34a overexpression inhibited CD44 expression and cell-crystals adhesion; whereas CD44 overexpression showed reversed results. Furthermore, miR-34a suppressed cell-crystals adhesion and stone formation in vivo. These findings indicate that miR-34a targets CD44 in HK-2 cells and inhibits cell-crystal adhesion both in vitro and in vivo. Based on these results, miR-34a may be a potential therapeutic target for renal stone disease.

Nephrolithiasis in the Obese Patient

PURPOSE OF REVIEW

The link between metabolic syndrome (MetS)/obesity and kidney stone disease (KSD) has gained importance over recent years due to the increasing prevalence and healthcare burden worldwide. This review analyses the literature exploring the link between MetS/obesity and KSD and the impact that obesity has on KSD management.

RECENT FINDINGS

Metabolic syndrome has been shown to increase an individual's risk of developing kidney stone disease, with insulin resistance forming a core component of the pathophysiology. The body habitus of an individual also influences the type of intervention that is most appropriate, with flexible ureteroscopy increasingly being the preferred option in obese patients. It is important for urologists to consider the features of metabolic syndrome to effectively manage episodes of KSD in obese patients. In addition, better quality evidence is required to effectively compare different treatment options in this group of patients.

A Retrospective Study of Kidney Stone Recurrence in Adults

Background

Nephrolithiasis or kidney stone disease (KSD) is a common disorder worldwide. Despite the availability of a variety of effective management strategies, KSD recurrence remains a problem. In the present study, we investigated the KSD recurrence after the treatment of the first stone episode.

Methods

Medical records of all patients who had KDS treated in our department from January 2012 to January 2016 were retrospectively reviewed. A total of 146 patients who had KDS recurrence were identified. The demographic information, biochemical data, treatment methods, report of hydronephrosis severity and stone chemical compositions were collected and analyzed.

Results

We reported that: 1) Sixty four (43.8%) out of 146 patients with stone recurrence were overweight or obese; 2) Of all 146 patients with stone recurrence, 86 (58.9%) had hyperlipidemia, 77 (52.4%) had hyperuricemia and 64 (43.8%) had hyperglycemia; 3) Mini-invasive methods were mostly used for the treatment of the first stone episode; 4) The most chief complaint differed during the first episode and recurrence; 5) The number of patients who had grades 3 and 4 hydronephrosis was significantly lower during recurrence compared with that in the first stone episode; 6) Seventy nine (54.1%) patients with recurrence had stone of calcium oxalate.

Conclusions

Majority of patients with KSD recurrence have overweight/obesity, hyperlipidemia, hyperuricemia and hyperglycemia, indicating a role of metabolic disorders in stone recurrence. Mini-invasive methods are the mainstay for the management of the first stone episode. The degree of hydronephrosis is significantly reduced during stone recurrence, possibly due to increased awareness of the disease and thereafter the change of lifestyle in patients. Over half of recurrent stones are of calcium oxalate.

The comparison of oxidative stress effect in classic and tubeless percutaneous nephrolithotomy

Purpose

Surgical stone treatment induces oxidative stress in kidney tissue. We hypothesized that tubeless percutaneous nephrolithotomy (tPCNL) may induce less oxidative stress than classic percutaneous nephrolithotomy (cPCNL) with nephrostomy tube.

Methods

Seventy-two consecutive patients with kidney stones qualified for PCNL were enrolled in the study. Patients were assigned to one of two groups (first group 33 patients—cPCNL and second group 39 patients—tPCNL). Four urine samples were collected in four consecutive days, starting the day before operation. Four oxidative stress markers were analyzed in each sample: catalase (CAT), protein sulfhydryl group (SH), total antioxidant capacity (TAC) and superoxide dismutase (SOD).

Results

Baseline mean levels of CAT (IU/l), SH (μmol/l), TAC (mmol/l) and SOD (NU/ml) were 19.4 versus 11.7; 18 versus 58.7; 2.02 versus 1.99; 20.5 versus 22.6 in cPCNL and tPCNL group, respectively. On day two, the levels were 89 versus 104.9; 334.7 versus 518.9; 1.87 versus 1.79; 33.7 versus 41.4, respectively. On the third day, the levels were: 67.4 versus 28.3; 206.8 versus 306.9; 2.01 versus 2.06; 38.2 versus 36.6, respectively. On the fourth day, the concentrations were 47.4 versus 18.5; 129.3 versus 208.7; 2 versus 2.06; 35 versus 45.2, respectively. Significant differences were observed only for CAT and TAC concentrations in days 3 (p = 0.04 and 0.04) and 4 (p = 0.02 and < 0.001) in favor of tPCNL.

Conclusions

CAT, SH and SOD significantly rise after operation. TAC represents the inversion of other parameters. CAT is significantly lower, and TAC is significantly higher in tPCNL postoperatively favoring this method.

Urinary biomarkers in the early detection and follow-up of tubular injury in childhood urolithiasis

BACKGROUND

To investigate relationships among urinary biomarkers [kidney injury molecule-1 (KIM-1), N-acetyl-β-glucosaminidase (NAG)], neutrophil gelatinase-associated lipocalin (NGAL) levels and renal tubular injury in childhood urolithiasis.

METHODS

Seventy children [36 girls, mean age: 7.3 ± 5.0 years (0.5-18.2)] with urolithiasis/microlithiasis and 42 controls [18 girls, mean age: 8.5 ± 3.8 years (0.9-16.2)] were included in this multicenter, controlled, prospective cohort study. Patients were evaluated three times in 6-month intervals (0, 6 and 12th months). Anthropometric data, urinary symptoms, family history and diagnostic studies were recorded. Urine samples were analyzed for metabolic risk factors (urinary calcium, uric acid, oxalate, citrate, cystine, magnesium, and creatinine excretion), and the urinary KIM-1, NAG, and NGAL levels were measured.

RESULTS

Stones were mostly located in the upper urinary system (82.9%), and six patients (8.6%) had hydronephrosis. Thirty patients (42.9%) had several metabolic risk factors, and the most common metabolic risk factor was hypocitraturia (22.9%). Urinary KIM-1/Cr, NAG/Cr and NGAL/Cr ratios were not significantly different between patients and controls. Furthermore, no significant changes in their excretion were shown during follow-up. Notably, the urinary KIM-1/Cr, NAG/Cr, and NGAL/Cr levels were significantly higher in children under 2 years of age (p = 0.011, p = 0.006, and 0.015, respectively). NAG/Cr and NGAL/Cr ratios were significantly increased in patients with hydronephrosis (n = 6, p = 0.031 and 0.023, respectively).

CONCLUSIONS

The results of this study suggest that none of the aforementioned urinary biomarkers (KIM-1, NAG and NGAL levels) may be useful for the early detection and/or follow-up of renal tubular injury and/or dysfunction in childhood urolithiasis.

A Complete World Literature Review of Quality of Life (QOL) in Patients with Kidney Stone Disease (KSD)

Purpose of Review

The purpose of this study was to review the current evidence for quality of life (QOL) in patients with kidney stone disease (KSD).

Recent Findings

A review of literature from inception to May 2016 for all prospective English language articles on QOL in patients with KSD was done. QOL studies post urological procedures or ureteric stents were excluded. Nine studies (1570 patients) were included of which most (n = 6) used the SF-36 QOL tool. Overall, seven of the nine studies demonstrated a lower QOL in patients with KSD. Bodily pain and general health were significantly lower in patients with KSD compared to their control groups.

Summary

Patients with KSD have an overall lower QOL with most impact on bodily pain and general health domains. Compared to the scale of patients suffering from KSD, more work needs to be done in measuring QOL both in terms of ‘Stone specific’ QOL measuring tools and the quality/number of studies in this field.

The effects of bariatric surgery on bone and nephrolithiasis

The impact of bariatric surgery on cardiovascular and diabetic complications associated with an improvement in survival has overshadowed the adverse skeletal health and development of kidney stone disease in this population. All longitudinal based studies in the literature reporting the incidence of bone fractures or kidney stones following bariatric surgery were reviewed. Moreover, all publications over the past decade which assessed changes in bone mineral density and bone quality, or explored underlying pathophysiologic mechanisms of bone and kidney stone disease were carefully reviewed. This review provides sufficient data to support that osteoporotic fractures and kidney stone disease are associated with Roux-en-Y gastric bypass surgery. However, due to the limited data available to date, no definitive conclusion could yet be drawn whether sleeve gastrectomy or adjustable gastric banding is associated with bone fractures and kidney stones. Bariatric surgery has emerged as the most effective and sustained treatment for weight reduction. This treatment modality has been recognized to diminish the risk of cardiovascular morbidity and mortality and ameliorate diabetes mellitus complications. The derangement in mineral metabolism has emerged as a major complication following bariatric surgery.

Review on renal recovery after anatrophic nephrolithotomy: Are we really healing our patients?

The main goals for urinary stone treatment are to preserve renal function, reduce or avoid complications related to calculi, and to render the patient free of calculi as soon as possible. Anatrophic nephrolithotomy (ANL) is a valid and useful alternative for conventional staghorn calculi excision. Although excellent stone free rates can be achieved with ANL there are some drawbacks that may be of concern. Morbidity related to intraoperative and postoperative complications is one of them. Another, great concern is the possibility of reduction on renal function related to the procedure itself. This may be related to nephron injury during nephrotomy and parenchymal closure or to ischemic injury. In this review we assess functional results after anatrophic nephrolithotomy.

Diabetic severity and risk of kidney stone disease

BACKGROUND

The prevalence of kidney stone disease is rising along with increasing rates of obesity, type 2 diabetes mellitus (T2DM), and metabolic syndrome.

OBJECTIVE

To investigate the associations among the presence and severity of T2DM, glycemic control, and insulin resistance with kidney stone disease.

DESIGN, SETTING, AND PARTICIPANTS

We performed a cross-sectional analysis of all adult participants in the 2007-2010 National Health and Nutrition Examination Survey (NHANES). A history of kidney stone disease was obtained by self-report. T2DM was defined by self-reported history, T2DM-related medication usage, and reported diabetic comorbidity. Insulin resistance was estimated using fasting plasma insulin (FPI) levels and the homeostasis model assessment of insulin resistance (HOMA-IR) definition. We classified glycemic control using glycosylated hemoglobin A1c (HbA1c) and fasting plasma-glucose levels (FPG).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Odds ratios (OR) for having kidney stone disease were calculated for each individual measure of T2DM severity. Logistic regression models were fitted adjusting for age, sex, race/ethnicity, smoking history, and the Quételet index (body mass index), as well as laboratory values and components of metabolic syndrome.

RESULTS AND LIMITATIONS

Correlates of kidney stone disease included a self-reported history of T2DM (OR: 2.44; 95% confidence interval [CI], 1.84-3.25) and history of insulin use (OR: 3.31; 95% CI, 2.02-5.45). Persons with FPG levels 100-126 mg/dl and >126 mg/dl had increased odds of having kidney stone disease (OR 1.28; 95% CI, 0.95-1.72; and OR 2.29; 95% CI, 1.68-3.12, respectively). Corresponding results for persons with HbA1c 5.7-6.4% and ≥ 6.5% were OR 1.68 (95% CI, 1.17-2.42) and OR 2.82 (95% CI, 1.98-4.02), respectively. When adjusting for patient factors, a history of T2DM, the use of insulin, FPI, and HbA1c remained significantly associated with kidney stone disease. The cross-sectional design limits causal inference.

CONCLUSIONS

Among persons with T2DM, more-severe disease is associated with a heightened risk of kidney stones.

Qualification and application of an ELISA for the determination of Tamm Horsfall protein (THP) in human urine and its use for screening of kidney stone disease

Kidney stone disease affects 1 - 20% of the general population. At present, the diagnosis of a stone is done using radiography method when noticeable symptoms appeared. We developed a non-invasive quantitative assay for urinary THP, namely ELISA; whereby our previous study and other reports had shown the usefulness of THP as biomarker for kidney stone disease. Since urine is biological fluid that is easily obtainable, this method could be used as a screening assay for kidney stone prior to confirmation with radiography. The ELISA gave assay linearity r(2) > 0.999 within the range of 109 ng/mL to 945 ng/mL THP. Assay precisions were < 4% (C.V.) for repeatability and < 5% (C.V.) for reproducibility. Assay accuracy range from 97.7% to 101.2% at the various THP concentrations tested. Assay specificity and sensitivity were 80% and 86%, respectively. The cut-off points at P < 0.05 were 37.0 and 41.2 mug/mL for male and female, respectively. The assay is cost effective and rapid whereby the cost for assaying each urine sample in duplicate is approximately USD0.35 and within 5 hours, 37 samples can be assayed alongside full range of standards and 3 QC samples in each plate. Furthermore, sample preparation is relatively easy where urine sample was diluted 10 times in TEA buffer. The usability of the ELISA method for diagnosis of kidney stone disease is evaluated with 117 healthy subjects and 58 stone formers.