Urinary stone disease in diabetes mellitus

Risk of multiple lower and upper urinary tract problems among male older adults with type-2 diabetes: a population-based study

AIM

This study explores the risk of diabetes-associated lower and upper urinary tract diseases among male older adults aged 45 and above in India.

METHODS

Longitudinal Ageing Study in India (LASI), 2017-2018 data was used in this study. The prevalence of various urinary tract problems and diabetes among male older adults was estimated by background characteristics using bivariate cross-tabulation. In addition, multivariate logistic regression was applied to examine the likelihood of urological disorders associated with diabetes.

RESULT

The prevalence of incontinence was highest among male older adults with diabetes, followed by kidney stones, benign prostatic hyperplasia, and chronic renal failure. Multivariate logistic regression estimation showed that men diagnosed with diabetes were 80% more likely to experience chronic renal failure, 78% more likely to suffer from incontinence, and 37% more likely to suffer from kidney stones than those without diabetes when controlling for various socio-demographic, behavioral, and co-morbidity status of the older adults.

CONCLUSIONS

The study findings suggest that diabetes is associated with multiple urinary complications among male older adults in India and needs more careful investigation of the phenomenon. Independent risk factors such as changes in lifestyle with regular monitoring and diagnosis may help to prevent the progression of diabetes and reduce the risk of diabetes-associated lower and upper urinary tract diseases among male older adults.

Sleep and circadian rhythm disturbance in kidney stone disease: a narrative review

The circadian rhythm generated by circadian clock genes functions as an internal timing system. Since the circadian rhythm controls abundant physiological processes, the circadian rhythm evolved in organisms is salient for adaptation to environmental change. A disturbed circadian rhythm is a trigger for numerous pathological events. Recently, accumulated data have indicated that kidney stone disease (KSD) is related to circadian rhythm disturbance. However, the mechanism between them has not been fully elucidated. In this narrative review, we summarized existing evidence to illustrate the possible association between circadian rhythm disturbance and KSD based on the epidemiological studies and risk factors that are linked to circadian rhythm disturbance and discuss some chronotherapies for KSD. In summary, KSD is associated with systemic disorders. Metabolic syndrome, inflammatory bowel disease, and microbiome dysbiosis are the major risk factors supported by sufficient data to cause KSD in patients with circadian rhythm disturbance, while others including hypertension, vitamin D deficiency, parathyroid gland dysfunction, and renal tubular damage/dysfunction need further investigation. Then, some chronotherapies for KSD were confirmed to be effective, but the molecular mechanism is still unclear.

2022 Recommendations of the AFU Lithiasis Committee: Epidemiology, stone analysis and composition

The incidence of urinary lithiasis is rising steadily in industrialized countries, and its prevalence in the general population of France is estimated at 10%. Renal colic accounts for 1-2% of emergency department consultations. At a time when the new LASER stone fragmentation techniques available to urologists will lead to ever finer in situ pulverization of stones, the exact identification of the compounds that form the stone is essential for etiological diagnosis. Constitutional analysis by infrared spectrophotometry or X-ray diffraction is therefore recommended, to be complemented by morphological typing of the calculi. METHODOLOGY: These recommendations have been drawn up using two methods: the Recommendation for Clinical Practice (RPC) method and the ADAPTE method, depending on whether or not the issue was considered in the EAU recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU 2022] and their adaptability to the French context.

Epidemiology of Kidney Stones

In the past two decades, major breakthroughs that improve our understanding of the pathophysiology and therapy of kidney stones (KS) have been lacking. The disease continues to be challenging for patients, physicians, and healthcare systems alike. In this context, epidemiological studies are striving to elucidate the worldwide changes in the patterns and the burden of the disease and identify modifiable risk factors that contribute to the development of kidney stones. Our expanding knowledge of the epidemiology of kidney stones is of paramount importance and largely upgrades the modern management of the disease. In this paper, we review the variables affecting prevalence and incidence, including age, gender, race, ethnicity, occupation, climate, geography, systemic diseases, diabetes, vascular disease, chronic kidney disease, and dietary risk factors relevant to kidney stones.

Urinary stone composition analysis and clinical characterization of 1520 patients in central China

A total of 1520 patients with urinary stones from central China were collected and analysed by Fourier transform infrared spectroscopy between October 1, 2016 and December 31, 2019. For all patients, age, sex, comorbidities, stone location, laboratory examination and geographic region were collected. The most common stone component was calcium oxalate (77.5%), followed by calcium phosphate (8.7%), infection stone (7.6%), uric acid (UA) stone (5.3%)and cystine (0.9%). The males had more calcium oxalate stones (p < 0.001), while infection stone and cystine stones occurred more frequently in females (p < 0.001). The prevalence peak occurred at 41-60 years in both men and women. UA stones occurred frequently in patients with lower urinary pH (p < 0.001), while neutral urine or alkaline urine (p < 0.001) and urinary infection (p < 0.001) were more likely to be associated with infection stone stones. Patients with high levels of serum creatinine were more likely to develop UA stones (p < 0.001). The proportion of UA stones in diabetics was higher (p < 0.001), and the incidence of hypertension was higher in patients with UA stones (p < 0.001). Compared to the other types, more calcium oxalate stones were detected in the kidneys and ureters (p < 0.001), whereas struvite stones were more frequently observed in the lower urinary tract (p = 0.001). There was no significant difference in stone composition across the Qinling-Huaihe line in central China except UA stones, which were more frequently observed in patients south of the line (p < 0.001).

Sodium Oxalate-Induced Acute Kidney Injury Associated With Glomerular and Tubulointerstitial Damage in Rats

Acute crystalline nephropathy is closely related to tubulointerstitial injury, but few studies have investigated glomerular changes in this condition. Thus, in the current study, we investigated the factors involved in glomerular and tubulointerstitial injury in an experimental model of crystalline-induced acute kidney injury (AKI). We treated male Wistar rats with a single injection of sodium oxalate (NaOx, 7 mg⋅100 g^-1⋅day^-1, resuspended in 0.9% NaCl solution, i.p.) or vehicle (control). After 24 h of treatment, food and water intake, urine output, body weight gain, and renal function were evaluated. Renal tissue was used for the morphological studies, quantitative PCR and protein expression studies. Our results revealed that NaOx treatment did not change metabolic or electrolyte and water intake parameters or urine output. However, the treated group exhibited tubular calcium oxalate (CaOx) crystals excretion, followed by a decline in kidney function demonstrated along with glomerular injury, which was confirmed by increased plasma creatinine and urea concentrations, increased glomerular desmin immunostaining, nephrin mRNA expression and decreased WT1 immunofluorescence. Furthermore, NaOx treatment resulted in tubulointerstitial injury, which was confirmed by tubular dilation, albuminuria, increased Kim-1 and Ki67 mRNA expression, decreased megalin and Tamm-Horsfall protein (THP) expression. Finally, the treatment induced increases in CD68 protein staining, MCP-1, IL-1β, NFkappaB, and α-SMA mRNA expression, which are consistent with proinflammatory and profibrotic signaling, respectively. In conclusion, our findings provide relevant information regarding crystalline-induced AKI, showing strong tubulointerstitial and glomerular injury with a possible loss of podocyte viability.

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.

Diabetes Mellitus Might Not Be Associated with Any Stone Component in a Local District

BACKGROUND

Type II diabetes mellitus (DM) is a risk factor for urinary stones, but the pathogenesis remains unclear. The aim of our study was to present the distribution of stone components between DM and no DM group from a local stone center in China and to help the prevention department in decision-making.

METHODS

We reviewed the records of patients with upper urinary stones attending our hospital from January 2015 to September 2018. The patients with complete information were divided into 2 groups: type II DM group (DM group) and without DM group (no DM group). The distribution of stone components was analyzed.

RESULTS

Two hundred twenty-two patients were complicated with DM, whereas 1,894 (89%) were not. Significant difference was found in the distribution of hypertension and BMI (p = 0, p = 0, respectively). Distribution of sex, age, and stone components did not differ between the 2 groups. By the binary logistic analysis, increasing age and sex seemed to be the main risk factors influencing the stone components. Only the calcium stone seemed to be free of the -impact from age and sex. Occurrence of hypertension is a single risk factor for calcium stone from our analysis. Presence of diabetes and increasing BMI was not found to be significantly associated with the risk for any stone component.

CONCLUSIONS

In a local district, DM might not be the main factor associated with an increased risk for uric acid stone formation or any stone component. We should also consider the local characteristics of the stone distribution.

Predictive Factors for Kidney Stone Recurrence in Type 2 Diabetes Mellitus

OBJECTIVE

To determine the predictive factors for kidney stone recurrence in type 2 diabetic patients.

METHODS

A retrospective cohort study was conducted from 2013 to 2019 by using the database of diabetic patients diagnosed with kidney stone disease. The patients were divided into 2 groups according to stone disease status: recurrent stone and nonrecurrent stone. Baseline characteristics were compared and logistic regression was done to assess which variables could predict a stone recurrence.

RESULTS

There were 1617 type 2 diabetic patients with kidney stone disease, 1244 (77%) did not have a stone recurrence and 373 (23%) had a stone recurrence. Of these patients with recurrent stone, 40% had asymptomatic stones, 43% visited emergency department, and 45% required a surgical intervention. Median time to recurrence was 64 months. Multivariable analysis revealed that body mass index (odds ratios [OR] 1.032, 95% confidence interval [CI] 1.016-1.047), urine pH (OR 0.500, CI 0.043-0.581), HbA1c (OR 1.186, CI 1.012-1.277), diabetic neuropathy (OR 1.839, CI 1.413-2.392), diabetic retinopathy (OR 1.690, CI 1.122-2.546), insulin as well as potassium citrate therapy (OR 0.611, CI 0.426-0.87), and stone with calcium oxalate and uric acid composition (OR 1.955, CI 1.420-2.691 and OR 2.221, CI 1.249-3.949, respectively) are significant predictors for stone recurrence.

CONCLUSION

The severity of diabetes and stone composition are strong predictors for stone recurrence in type 2 diabetic patients, while HbA1c and urine pH are important modifiable factors.

Urinary oxalate as a potential mediator of kidney disease in diabetes mellitus and obesity

PURPOSE OF REVIEW

Hyperoxaluria can cause kidney disease through multiple mechanisms, including tubular obstruction from calcium oxalate crystals, sterile inflammation, and tubular epithelial cell injury. Hyperoxaluria is also observed in individuals with diabetes mellitus and obesity, which are in turn risk factors for chronic kidney disease (CKD). Whether hyperoxaluria is a potential mediator of increased risk of CKD in diabetes mellitus and obesity is unknown.

RECENT FINDINGS

Individuals with diabetes have increased levels of plasma glyoxal (a protein glycation product) and glyoxylate, both of which are precursors for oxalate. Increased gut absorption of oxalate in obesity may be because of obesity-associated inflammation. A recent study in individuals with CKD found that higher 24 h urinary oxalate excretion was independently associated with increased risk of kidney disease progression, especially in individuals with diabetes and obesity.

SUMMARY

Both diabetes mellitus and obesity are associated with higher urinary oxalate excretion through distinct mechanisms. Hyperoxaluria could be a mechanism by which kidney disease develops in individuals with diabetes mellitus or obesity and could also contribute to progressive loss of renal function. Future research on pharmacologic or dietary measures to limit oxalate absorption or generation are required to test whether lowering urinary oxalate excretion is beneficial in preventing kidney disease development and progression in diabetes mellitus and obesity.

Does chronic hyperglycaemia increase the risk of kidney stone disease? results from a systematic review and meta-analysis

DESIGN

Systematic review and meta-analysis of observational studies was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for studies reporting on diabetes mellitus (DM) or metabolic syndrome (MetS) and kidney stone disease (KSD).

OBJECTIVE

To examine the association between chronic hyperglycaemia, in the form of DM and impaired glucose tolerance (IGT) in the context of MetS and KSD.

SETTING

Population-based observational studies. Databases searched: Ovid MEDLINE without revisions (1996 to June 2018), Cochrane Library (2018), CINAHL (1990 to June 2018), ClinicalTrials.gov, Google Scholar and individual journals including the Journal of Urology, European Urology and Kidney International.

PARTICIPANTS

Patients with and without chronic hyperglycaemic states (DM and MetS).

MAIN OUTCOME MEASURES

English language articles from January 2001 to June 2018 reporting on observational studies.

EXCLUSIONS

No comparator group or fewer than 100 patients. Unadjusted values were used for meta-analysis, with further meta-regression presented as adjusted values. Bias was assessed using Newcastle-Ottawa scale.

RESULTS

2340 articles were screened with 13 studies included for meta-analysis, 7 DM (three cohort) and 6 MetS. Five of the MetS studies provided data on IGT alone. These included: DM, n=28 329; MetS, n=31 767; IGT, n=12 770.

CONTROLS

DM, n=5 89 791; MetS, n=1 78 050; IGT, n=2 93 852 patients. Adjusted risk for DM cohort studies, RR=1.23 (0.94 to 1.51) (p<0.001). Adjusted ORs for: DM cross-sectional/case-control studies, OR=1.32 (1.21 to 1.43) (p<0.001); IGT, OR=1.26 (0.92 to 1.58) (p<0.0001) and MetS, OR=1.35 (1.16 to 1.54) (p<0.0001). There was no significant difference between IGT and DM (cross-sectional/case-control), nor IGT and MetS. There was a moderate risk of publication bias. Statistical heterogeneity remained significant in adjusted DM cohort values and adjusted IGT (cross-sectional/case-control), but non-signficant for adjusted DM (cross-sectional/case-control).

CONCLUSION

Chronic hyperglycaemia increases the risk of developing kidney stone disease. In the context of the diabetes pandemic, this will increase the burden of stone related morbidity and mortality.

PROSPERO REGISTRATION NUMBER

CRD42018093382.

Performance of a Natural Language Processing Method to Extract Stone Composition From the Electronic Health Record

OBJECTIVES

To demonstrate the utility of a natural language processing (NLP) algorithm for mining kidney stone composition in a large-scale electronic health records (EHR) repository.

METHODS

We developed StoneX, a pattern-matching method for extracting kidney stone composition information from clinical notes. We trained the extraction algorithm on manually annotated text mentions of calcium oxalate monohydrate, calcium oxalate dihydrate, hydroxyapatite, brushite, uric acid, and struvite stones. We employed StoneX to identify patients with kidney stone composition data and mine >125 million notes from our institutional EHR. Analyses performed on the extracted patients included stone type conversions over time, survival analysis from a second stone surgery, and disease associations by stone composition to validate the phenotyping method against known associations.

RESULTS

The NLP algorithm identified 45,235 text mentions corresponding to 11,585 patients. Overall, the system achieved positive predictive value >90% for calcium oxalate monohydrate, calcium oxalate dihydrate, hydroxyapatite, brushite, and struvite; except for uric acid (positive predictive value = 87.5%). Survival analysis from a second stone surgery showed statistically significant differences among stone types (P = .03). Several phenotype associations were found: uric acid-type 2 diabetes (odds ratio, OR = 2.69, 95% confidence intervals, CI = 1.91-3.79), struvite-neurogenic bladder (OR = 12.27, 95% CI = 4.33-34.79), struvite-urinary tract infection (OR = 7.36, 95% CI = 3.01-17.99), hydroxyapatite-pulmonary collapse (OR = 3.67, 95% CI = 2.10-6.42), hydroxyapatite-neurogenic bladder (OR = 5.23, 95% CI = 2.05-13.36), brushite-calcium metabolism disorder (OR = 4.59, 95% CI = 2.14-9.81), and brushite-hypercalcemia (OR = 4.09, 95% CI = 1.90-8.80).

CONCLUSION

NLP extraction of kidney stone composition from large-scale EHRs is feasible with high precision, enabling high-throughput epidemiological studies of kidney stone disease. These tools will enable high fidelity kidney stone research from the EHR.

New-onset metabolic risk factors and the incidence of kidney stones: a prospective cohort study

OBJECTIVE

To examine the association of kidney stones with new-onset hypertension, diabetes and obesity.

PARTICIPANTS AND METHODS

This prospective cohort study included participants in the Qingdao Port Cardiovascular Health Study who were aged ≥18 years and had abdominal ultrasonography results in 2013 that were negative for kidney stones. Multivariable Cox regression models with time-dependent covariates were used to estimate the effects of new-onset hypertension, diabetes and obesity on the incidence of kidney stones.

RESULTS

There were 9667 participants without kidney stones in 2013 (mean age 46.2 years; 75.6% men). During a mean (range) follow-up of 33.5 (6-42) months, 676 (7.0%) incident cases of kidney stones were identified. Kidney stones were more frequent among those who had new-onset of a metabolic factor vs those who did not (hypertension: 7.7 vs 6.0%; diabetes: 8.4 vs 6.6%; obesity: 7.4 vs 6.8%). Adjusted Cox models identified that increased risk of kidney stones was associated with new-onset hypertension (adjusted hazard ratio [HR] 1.69, 95% confidence interval [CI] 1.25-2.27), new-onset diabetes (HR 1.78, 95% CI 1.07-2.96), and new-onset obesity (HR 1.78, 95% CI 1.15-2.74).

CONCLUSIONS

New-onset of hypertension, diabetes and obesity were all strongly associated with an increased risk of kidney stones in this prospective cohort study. Results suggest that a substantial proportion of kidney stones are potentially preventable by appropriate control of these metabolic risk factors.

Phase composition and morphological characterization of human kidney stones using IR spectroscopy, scanning electron microscopy and X-ray Rietveld analysis

Pathological calcification in human urinary tract (kidney stones) is a common problem affecting an increasing number of people around the world. Analysis of such minerals or compounds is of fundamental importance for understanding their etiology and for the development of prophylactic measures. In the present study, structural characterization, phase quantification and morphological behaviour of thirty three (33) human kidney stones from eastern India have been carried out using IR spectroscopy (FT-IR), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). Quantitative phase composition of kidney stones has been analyzed following the Rietveld method. Based on the quantitative estimates of constituent phases, the calculi samples have been classified into oxalate (OX), uric acid (UA), phosphate (PH) and mixed (MX) groups. Rietveld analysis of PXRD patterns showed that twelve (36%) of the renal calculi were composed exclusively of whewellite (calcium oxalate monohydrate, COM). The remaining twenty one (64%) stones were mixture of phases with oxalate as the major constituent in fourteen (67%) of these stones. The average crystallite size of whewellite in oxalate stones, as determined from the PXRD analysis, varies between 93 (1) nm and 202 (3) nm, whereas the corresponding sizes for the uric acid and struvite crystallites in UA and PH stones are 79 (1)-155 (4) nm and 69 (1)-123(1) nm, respectively. The size of hydroxyapatite crystallites, 10 (1)-21 (1) nm, is smaller by about one order of magnitude compared to other minerals in the kidney stones. A statistical analysis using fifty (50) kidney stones (33 calculi from the present study and 17 calculi reported earlier from our laboratory) revealed that the oxalate group (whewellite, weddellite or mixture of whewellite and weddellite as the major constituent) is the most prevalent (82%) kidney stone type in eastern India.

Relationship between urine pH and abnormal glucose tolerance in a community-based study

AIMS/INTRODUCTION

The association between urine pH and abnormal glucose tolerance in men and women is unclear; therefore, we carried out a community-based, cross-sectional study to investigate sex-specific associations between these values, possible indicators of prediabetes and type 2 diabetes.

MATERIALS AND METHODS

We enrolled 4,945 Japanese individuals (2,490 men and 2,455 women), who had undergone annual health checkups. To investigate the relationship between low urine pH and abnormal glucose tolerance, participants were divided into three groups based on their fasting plasma glucose levels (<6.11 mmol/L, 6.11-6.99 mmol/L and ≥6.99 mmol/L), and three groups based on their glycated hemoglobin levels (≤44.3 mmol/mol, 44.3-47.5 mmol/mol and ≥47.5 mmol/mol). To examine the effects of urine pH on abnormal glucose tolerance, participants were categorized into five groups based on their urine pH (5.0, 5.5, 6.0, 6.5 and ≥7.0).

RESULTS

Multivariate analysis adjusted for age, body mass index, systolic blood pressure, triglycerides, high-density lipoprotein cholesterol, uric acid, creatinine and antidiabetic agent use showed significant associations between low urine pH and both high fasting plasma glucose and high glycated hemoglobin levels (P for trend = 0.0260, 0.0075) in men. Furthermore, after the same adjustments, prevalence rates of abnormal glucose tolerance (≥6.11 mmol/L and ≥6.99 mmol/L), increased significantly as urine pH levels decreased (P for trend = 0.0483, 0.0181) in men. In women, a similar trend was observed without a significant difference.

CONCLUSIONS

Low urine pH is significantly associated with abnormal glucose tolerance; therefore, measuring urine pH might prove useful for identifying patients at high risk for diabetes.

Successful Diabetic Control as Measured by Hemoglobin A1c Is Associated with Lower Urine Risk Factors for Uric Acid Calculi

INTRODUCTION AND OBJECTIVES

To examine the association of glycemic control, including strict glycemic control, with 24-hour urine risk factors for uric acid and calcium calculi.

MATERIALS AND METHODS

With institutional review board (IRB) approval, we identified 183 stone formers (SFs) with 459 twenty-four-hour urine collections. Hemoglobin A1c (HgbA1c) measures were obtained within 3 months of the urine collection. Collections were categorized into normoglycemic (NG, HgbA1c < 6.5) and hyperglycemic (HG, HgbA1c ≥ 6.5) cohorts; 24-hour urine parameters were compared. The NG cohort was further divided into patients with and without a history of diabetes mellitus (DM) type 2. Variables were analyzed using chi-square, Welch's t-test and multivariate linear regression to adjust for clustering, body mass index (BMI), age, gender, thiazide use, and potassium citrate use.

RESULTS

Patients in the HG group were older with higher BMI. Multivariate analysis of the total study population revealed that hyperglycemia correlated with lower pH, higher uric acid relative saturation (RS), lower brushite RS, and higher citrate. NG SFs with and without a history of DM had similar risk factors for uric acid stone formation. Among NG SFs, those with DM had higher urine calcium and calcium oxalate RS than those without DM. However, this difference may be related to other factors since neither parameter correlated with DM on multivariate regression (p > 0.05).

CONCLUSIONS

Successful glycemic control may be associated with reduced urinary risk factors for uric acid stone formation. Patients with well-controlled DM had equivalent risk factors to those without DM. Glycemic control should be considered a target of the multidisciplinary medical management of stone disease.

Determinants of Crystalluria among Type 2 Diabetes Patients; A Case-Control Study of the Agona West Municipality, Ghana

BACKGROUND/AIM

Type 2 diabetes mellitus (T2DM) has been implicated as a risk factor for nephrolithiasis. The aim of this study was to determine the prevalence and types of crystalluria among individuals with T2DM. It further sought to identify associated risks, which could influence crystalluria.

METHODS

A case-control study with random sampling of 165 diabetes patients (cases) and 40 healthy non-diabetics (controls) was conducted from December 2012 to May 2013 at the Agona Swedru Municipal Hospital, Ghana. Sociodemographic and anthropometric data were obtained from the participants. Blood and urine samples were collected for the estimation of blood glucose (fasting) and urinalysis for the presence of crystals, respectively (light microscopy).

RESULTS

Overall frequency of crystalluria was 18.0%. The prevalence of urine crystals in diabetics (17.5%) was more than that in non-diabetics (5.0%). Types of crystals found in the T2DM patients by prevalence were calcium oxalate (12.7%), uric acid (3.6%), and tyrosine (1.2%). Mean age, body mass index, systolic blood pressure, and fasting blood glucose (FBG) were higher among case participants than in controls (P < 0.001; P < 0.001; P = 0.018; P < 0.001). Case participants had a lower urine pH than the controls (P < 0.001). Crystalluria was positively correlated with FBG (P = 0.002) and negatively with urine pH (P = 0.108). On multivariate analysis, FBG was independently associated with crystalluria (P = 0.002), after adjustment for other factors.

CONCLUSION

Crystalluria is common in diabetes patients. Acidic urine pH is mostly seen in T2DM and may be a predisposing factor to crystalluria. Good glycemic control may be a helpful in reducing the occurrence of crystalluria among T2DM.

Association Study of Reported Significant Loci at 5q35.3, 7p14.3, 13q14.1 and 16p12.3 with Urolithiasis in Chinese Han Ethnicity

In this study, we aimed to validate the association of 8 reported significant loci at 5q35.3, 7p14.3, 13q14.1 and 16p12.3 with urolithiasis in Chinese Han population. We performed case-control association analysis using 624 patients with nephrolithiasis and 1008 control subjects. We selected single-nucleotide polymorphism (SNPs) including rs12654812 and rs11746443 from 5q32.3; rs12669187 and rs1000597 from 7q14.3; rs7981733, rs4142110 and rs17646069 from 13q14.1 and rs4293393 from 16p12.3 which were previously reported to be associated with nephrolithiasis. We found none of these eight reported SNPs were significant associated with urolithiasis risk in Chinese Han population, which suggested that differences could exist in the mechanisms of calcium urolithiasis between Chinese and Japanese Ethnics. The A allele of rs12669187 was significantly correlated with increased level of serum magnesium. The C allele of rs1000597 was associated with higher levels of serum creatinine, uric acid, calcium and lower urine pH level. The T allele of rs4142110 was correlated with higher levels of serum magnesium, phosphorus, and lower AKP level. The G alleles of rs4293393 was associated with higher serum CO₂ level. The risk alleles of these SNPs were proved to be associated with the electrolytes metabolism that may result in the formation of urolithiasis.

Type 2 diabetes mellitus and renal stones

BACKGROUND

The incidence of urinary stone disease has shown a steep rise in recent decades along with marked modifications in dietary habits and life- style. There has been an increased prevalence of urinary stone disease in patients with diabetes. We took up this study to determine the association of diabetes mellitus with kidney stones in patients undergoing surgical treatment.

MATERIALS AND METHODS

Patients presenting with renal stones for surgical management formed the study group. Body mass index (BMI) was calculated by noting the weight and height of the patient. The extracted stone/stone fragments were analyzed to determine the chemical composition. Urinary pH was similarly noted in all.

RESULTS

The mean BMI among the diabetics was 26.35 ± 5.20 (range 17.75-35.60), whereas the mean BMI among the non-diabetics was 23.41 ± 2.85 (range 17.71-31.62) (P < 0.0004). The incidence of uric acid calculi in the diabetics was significantly high (P < 0.03). The mean urinary pH among the diabetics was 5.61 ± 0.36 and among the non-diabetics was 6.87 ± 0.32, which was significantly lower (P < 0.000044).

CONCLUSIONS

There is a strong association between type 2 diabetes and uric acid stone formation. There is also a strong association between diabetes mellitus, BMI, and also with lower urinary pH.

Do Hypertension, diabetes mellitus and obesity increase the risk of severity of nephrolithiasis?

Objective:

In this study we planned to investigate the relationship between presence of kidney stones and stone burden with hypertension (HT), diabetes mellitus (DM) and body mass index (BMI).

Methods:

A total of 574 patients were included in the study. None of the patients had a history of stones. The 121 patients with kidney stone identified on ultrasound evaluation and the 453 patients with no stones were compared in terms of HT, BMI and DM. The stone burden of 121 patients with diagnosed stones was compared in terms of the same variables.

Results:

Of the 121 patients with kidney stones 30 (24.7%) had HT, while 66 (14.5%) of the 453 patients without stones had HT (p=0.007). BMI values of those with and without stones were 27.2 ± 4.93 kg/m² and 25.29 ± 4.12 kg/m², respectively (p<0.001). Twenty-five (20.6%) of the patients with stones diagnosed by ultrasound had DM, while 49 (10.8%) of those without stones had DM (p=0.004). When comparing patients with and without kidney stones, logistic regression analysis revealed that DM (odds ratio [OR] 2.06, 95% confidence interval [CI] 1.17 to 3.63, p=0.013) and BMI (OR 1.08, CI 1.03 to 1.13, p=0.003) were independently associated with presence of stones. No significant relationship was found between the same variables and cumulative stone diameter (CSD) and stone surface area (SA) evaluated for stone burden.

Conclusions:

While diabetes mellitus, Hypertension and increased Body Mass Index may add to the possibility of stone formation, they did not affect stone burden.

The relationship between insulin, insulin resistance, parathyroid hormone, cortisol, testosterone, and thyroid function tests in the presence of nephrolithiasis: a comprehensive analysis

Introduction

Previous studies have shown that hormonal factors such as levels of insulin, cortisol, testosterone, and insulin resistance are related with increased nephrolithiasis (NL). However, no previous study has evaluated the relationship between insulin, insulin resistance, thyroid hormones, cortisol, intact parathyroid hormone and testosterone levels with the presence of NL in a comprehensive manner.

Materials and methods

All patients underwent the following procedures: history taking, physical examination, biochemical analysis [including measurement of levels of insulin, thyroid hormones, cortisol, and total testosterone (for male patients only)], urine analysis, 24–hour urine collection to measure urinary protein, sodium excretion, and creatinine clearance. Insulin resistance was evaluated by the homeostasis model assessment index (HOMA–INDEX). The presence of NL was determined by ultrasonography.

Results

The study was composed of 136 patients. In total, 30 patients had NL. Patients with NL were more likely to be older, male, obese, and smokers. Uric acid and HOMA–INDEX were also higher in patients with NL. In the whole group, only insulin (Odds ratio:1.128, CI:1.029–1.236, P:0.01) but not other hormones, and HOMA–INDEX were related with the presence of NL. In males, none of the hormones including total testosterone were associated with NL.

Conclusions

Only levels of insulin, but not other hormones were associated with the presence of NL in a group of patients with suspicion of NL. More studies are needed to highlight the mechanisms regarding NL and hormone levels.

Age-related changes in 24-hour urine composition must be considered in the medical management of nephrolithiasis

BACKGROUND AND PURPOSE

Over the past 50 years, there has been an upward shift in the age of peak incidence of stone disease, yet less is known regarding how the urinary biochemical profile changes with aging. Therefore, we sought to examine the relationship between age and 24-hour urine composition.

METHODS

We retrospectively reviewed a database of our tertiary care stone clinic patients seen from March 2002 to February 2012. Analysis of pretreatment 24-hour urine collections across age groups was performed using univariate analysis of variance and multivariate linear regression models adjusting for clinical and demographic factors and 24-hour urine parameters.

RESULTS

A total of 1115 patients were broken down into age groups consisting of <45 years (221; 19.7%), 45-54.9 years (270; 23.8%), 55-64.9 years (270; 24.6%), and ≥65 years (356; 31.9%). Univariate analysis found significant ascending trends with aging for mean body mass index, while mean urine pH, 24-hour calcium, uric acid (UA), ammonium, creatinine, and supersaturation (SS) of calcium oxalate (CaOx) and calcium phosphate (CaP) decreased with age (all P for trend <0.05). Adjusted multivariate analysis demonstrated that increased age was significantly associated with increased 24-hour citrate and SS UA, whereas increased age was significantly associated with decreased pH, 24-hour UA, creatinine, SS CaOx, and SS CaP (all P for trend <0.05).

CONCLUSIONS

There are numerous age-related changes in the metabolic profile as seen on 24-hour urine collection. This highlights the importance of evaluating stone-forming patients of all ages with 24-hour urine collections because both the type and degree of metabolic abnormality may change with age.

The impact of metabolic syndrome on long-term outcomes of percutaneous nephrolithotomy (PCNL)

Study Type--Prognosis (cohort) Level of Evidence 2b. What's known on the subject? and What does the study add? The presence of metabolic syndrome is associated with development of kidney stones and an increase in the stone-recurrence rate. However, studies reporting long-term results of percutaneous nephrolithotomy (PCNL) in metabolic syndrome are lacking. The present study showed that metabolic syndrome was associated with worsening renal function at long-term follow-up and the stone-recurrence rate recurrence after PCNL in patients with metabolic syndrome was 3.2-fold higher compared with the control group.

OBJECTIVE

• To investigate the impact of metabolic syndrome on long-term kidney function and stone recurrence rates after percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

• In all, 73 patients with metabolic syndrome who underwent stone analysis and had a minimum follow-up of 12 months after PCNL were reviewed. • In addition, 73 patients without any metabolic syndrome components who had undergone PCNL and were followed-up for at least 12 months were included in the study as the control group. • These control group patients were selected from 226 patients who were matched with the patients with metabolic syndrome using a 1 : 1 ratio. The matching parameters were age, gender and stone size.

RESULTS

• Stone analyses showed that calcium oxalate monohydrate (52.0%) and uric acid (21.9%) were most common among patients with metabolic syndrome, whereas calcium oxalate monohydrate (76.7%) was the most common stone type in the control group. • Stone recurrences occurred with a mean (sd, range) of 36.1 (21.3, 12-109) months follow-up in 26 patients (41.9%) and 12 patients (18.9%) in the metabolic syndrome and control groups, respectively (P = 0.003). • While estimated glomerular filtration rate was decreased from 87.8 to 66.6 mL/min/1.73 m(2) in the metabolic syndrome group, it changed from 96.4 to 91.2 mL/min/1.73 m(2) in control group at long-term follow-up.

CONCLUSIONS

• The most frequent stone type was calcium oxalate monohydrate in patients with or without metabolic syndrome. • In patients with metabolic syndrome who underwent PCNL, the stone recurrence rate was >40%. • Metabolic syndrome is associated with worsening renal function at long-term follow-up.

Overweight and obesity: risk factors in calcium oxalate stone disease?

Introduction. Several studies showed an association of overweight and obesity with calcium oxalate stone disease (CaOx). However, there are no sufficient data on the influence of body weight on the course of the disease and the recurrence rate. Patients and Methods. N = 100 consecutive stone formers with pure CaOx were studied. Different parameters were investigated. According to the BMI, patients were divided into three groups: (1) BMI ≤ 25; (2) BMI 25.1-30; (3) BMI > 30. Results. N = 32 patients showed a BMI ≤ 25, n = 42 patients showed a BMI of 25.1-30 and n = 26 patients showed a BMI ≥ 30. The groups differed significantly concerning BMI (by definition), urine pH, and urine citrate. The recurrence rate was not significantly different. Discussion. Our study demonstrated that body weight negatively influences single risk factors in CaOx, but obesity is not a predictor for the risk of recurrence in CaOx.

Beware the low urine pH--the major cause of the increased prevalence of nephrolithiasis in the patient with type 2 diabetes

There is an increased prevalence of nephrolithiasis and an increase in the incidence of renal colic in patients with diabetes, obesity, hypertension and insulin resistance because of an increased frequency of uric acid crystallization. Uric acid crystallization occurs in the milieu of an acid urine and is not due to hyperuricosuria as with insulin resistance, urinary uric acid levels are generally decreased because of increased renal tubular reabsorption. However, in the presence of insulin resistance, there is decreased renal tubular generation of ammonia and increased sodium absorption leading to acidification of the urine and uric acid crystallization. The presence of a low urine pH should alert the clinician to the increased risk of nephrolithiasis particularly in the obese, diabetic or hypertensive patient. Prevention of nephrolithiasis can be achieved in susceptible individuals either by alkalizing the urine and/or by further decreasing the uric acid content of the urine with a xanthine oxidase inhibitor such as allopurinol.

Factors affecting kidney function and stone recurrence rate after percutaneous nephrolithotomy for staghorn calculi: outcomes of a long-term followup

PURPOSE

There are few studies of the long-term outcome of percutaneous nephrolithotomy for staghorn calculi. We report the long-term outcome of percutaneous nephrolithotomy in patients with staghorn calculi.

MATERIAL AND METHODS

A total of 265 study patients (272 renal units) were followed in the long term for greater than 12 months. The estimated glomerular filtration rate was calculated using the 4-variable modification of diet in renal disease equation. Cases were staged for chronic kidney disease by National Kidney Foundation guidelines. The impact of patient and procedure related factors on renal function as well as stone recurrence was analyzed retrospectively.

RESULTS

At a mean ± SD followup of 37.3 ± 25.4 months the chronic kidney disease stage classification was maintained in 177 patients (66.8%) while the classification of 34 (12.8%) and 54 (20.4%) had improved and deteriorated, respectively. Multivariate analysis revealed that an immediate postoperative change in the estimated glomerular filtration rate was the only factor predicting a change in renal function in the long term. Stones recurred in 73 of the 234 kidneys (31.2%) that were stone free 3 months after percutaneous nephrolithotomy. Stone size increased in 24 of the 38 kidneys (63.2%) with residual stones after intervention. Recurrent urinary infections during followup and diabetes were associated with stone recurrence and residual stone enlargement.

CONCLUSIONS

In almost 80% of patients with staghorn stones renal function was improved or maintained after percutaneous nephrolithotomy, as documented during long-term followup. Stones recurred in a third of the patients with staghorn calculi.

Nephrolithiasis: Endocrine evaluation

Nephrolithias is a common problem in populations around the world, and contribute significantly to the development of end stage renal disease. It is a matter of debate whether the metabolic factors responsible for renal stone formation are similar or variable in different populations around the globe. This review discusses the influence of different metabolic and dietary factor, and some other co-morbid conditions on the etiopathogenesis Nephrolithiasis. Evaluation and medical management of Nephrolithiasis is summarized in the later part of the article.

Is oxidative stress, a link between nephrolithiasis and obesity, hypertension, diabetes, chronic kidney disease, metabolic syndrome?

Epidemiological studies have provided the evidence for association between nephrolithiasis and a number of cardiovascular diseases including hypertension, diabetes, chronic kidney disease, metabolic syndrome. Many of the co-morbidities may not only lead to stone disease but also be triggered by it. Nephrolithiasis is a risk factor for development of hypertension and have higher prevalence of diabetes mellitus and some hypertensive and diabetic patients are at greater risk for stone formation. An analysis of the association between stone disease and other simultaneously appearing disorders, as well as factors involved in their pathogenesis, may provide an insight into stone formation and improved therapies for stone recurrence and prevention. It is our hypothesis that association between stone formation and development of co-morbidities is a result of certain common pathological features. Review of the recent literature indicates that production of reactive oxygen species (ROS) and development of oxidative stress (OS) may be such a common pathway. OS is a common feature of all cardiovascular diseases (CVD) including hypertension, diabetes mellitus, atherosclerosis and myocardial infarct. There is increasing evidence that ROS are also produced during idiopathic calcium oxalate (CaOx) nephrolithiasis. Both tissue culture and animal model studies demonstrate that ROS are produced during interaction between CaOx/calcium phosphate (CaP) crystals and renal epithelial cells. Clinical studies have also provided evidence for the development of oxidative stress in the kidneys of stone forming patients. Renal disorders which lead to OS appear to be a continuum. Stress produced by one disorder may trigger the other under the right circumstances.

Associations of insulin resistance and glycemic control with the risk of kidney stones

OBJECTIVE

The associations of insulin resistance and glycemic control with the risk of kidney stones were explored.

METHODS

Generally healthy Japanese (n=2,171) who visited Saiseikai Central Hospital (Tokyo, Japan) for a health check were included in a cross-sectional study. We calculated odds ratios (OR) of having kidney stones in terms of four measures: fasting serum insulin, homeostasis model assessment of insulin resistance (HOMA-IR), fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c), adjusting for possible risk factors for kidney stones.

RESULTS

Fasting serum insulin and HOMA-IR were non-significantly associated with the risk of kidney stones, whereas FPG and HbA1c were significantly associated. Compared with those with an FPG of <100 mg/dL, the ORs in those with an FPG of 100 to <126 mg/dL and ≥126 mg/dL were 1.38 (95% confidence interval [CI] =0.95-2.00) and 1.83 (95% CI =1.09-3.06) (p for trend =0.016). In relation to those with an HbA1c of <5.5%, the ORs in those with an HbA1c of 5.5 to <6.0%, 6.0% to <6.5% and ≥6.5% were 1.16 (95% CI =0.76-1.79), 1.25 (95% CI =0.70-2.23) and 1.98 (95% CI =1.11-3.52), respectively (p for trend =0.027). The significant associations between glycemic control measures and the risk of kidney stones were preserved even after the adjustment for factors related to insulin resistance.

CONCLUSION

Glycemic control could be an independent risk factor for kidney stones.

Updated epidemiologic study of urolithiasis in Turkey II: role of metabolic syndrome components on urolithiasis

The components of metabolic syndrome, such as obesity, hypertension, and diabetes, are thought to be associated with urolithiasis. However, there are few large-scale studies that have examined the association between metabolic syndrome and urolithiasis, which prompted us to study and evaluate the relationship between metabolic syndrome components and urolithiasis in a nationwide survey, using the cross-sectional study conducted by a professional investigation company, with 2,468 enrolled participants, aged between 18 and 70 years, from 33 provinces in Turkey. Participants were interviewed face-to-face by medical faculty students. Participants with a history of urolithiasis (Group 1) were compared with participants without a history of urolithiasis (Group 2) in terms of hypertension, diabetes, body-mass index (BMI), waist size, and trouser size using Chi-square and odds ratio tests. Of the 2,468 participants, 274 (11.1%) reported a history of urinary stone disease diagnosed by a physician. The percentage of participants with hypertension along with urolithiasis was significantly higher than that in participants without urolithiasis (16.9 and 34.3%, p 0.000, OR 3.0). The percentage of participants with diabetes in groups 1 and 2 was 14.2 and 9%, respectively (p 0.001, OR 1.83). The mean BMI was 27.2 and 25.2, respectively (p 0.01). Participants with a BMI >30 had a 2.2-fold increased risk of having urolithiasis. The mean waist size was significantly greater in participants with urolithiasis (p 0.000). Those with a waist size >100 cm had a 1.87-fold increased risk of having urolithiasis. The mean trouser size was also significantly larger in those participants who were stone formers (p 0.003). The results indicate that metabolic syndrome components are important factors in the development of urolithiasis.

Increased risk of urinary tract calculi among patients with diabetes mellitus--a population-based cohort study

OBJECTIVE

To investigate the inter-relationship among diabetes, urinary tract infection (UTI), and urinary tract calculi (UTC).

METHODS

This study used Taiwan's National Health Insurance claims data of ambulatory care visits and hospitalizations. A total of 12,257 newly diagnosed diabetes cases in 2000-2002 and 96,781 controls were followed to the end of 2007. The person-year approach with Poisson assumption was used to estimate the incidence density (ID) of UTC by diabetic status. Relative risk of UTC in relation to diabetes and UTI were estimated from Cox proportional hazard model with adjustment for sociodemographic variables and comorbidities.

RESULTS

Over nearly 8 years of follow-up, 8.9% of diabetes and 7.2% of control subjects sought ambulatory care or were hospitalized for UTC, representing the ID of 14.4 and 11.4 per 1000 person-years, respectively. The multivariate analysis indicated that UTC risk was independently associated with diabetes (hazard ratio 1.18, 95% CI 1.10-1.27) and UTI (HR 1.68, 95% CI 1.60-1.76). The hazard ratio of UTC in relation to diabetes in men and women without UTI was 1.24 and 1.26, respectively. Diabetes may further increase the rate of UTC in women with UTI, with an hazard ratio increased from 1.79-2.12. Such additive effect by diabetes in men with UTI was only marginal (HR 1.68 vs 1.67).

CONCLUSION

This cohort study provides epidemiologic support for the causal association between diabetes and UTC, which is independent of UTI. In addition, female patients with UTI accompanied by diabetes tended to be associated with a greater rate of UTC.

Metabolic syndrome and bariatric surgery in stone disease etiology

PURPOSE OF REVIEW

To review the prevalence and mechanisms of stone formation in patients with metabolic syndrome and in those submitted to bariatric surgery.

RECENT FINDINGS

MetS is associated with urinary stone disease, which appears to be sustained by dietetic factors and insulin resistance. The latter represented in obesity and diabetes favors uric acid precipitation in urine via a more acidic urinary load. Patients submitted to modern bariatric surgery are at risk of nephrolithiasis and nephropathy as a consequence of malabsorption and hyperoxaluria, which are more consistent after Roux-en-Y gastric bypass than after gastric banding. Other stone risk factors such as hypocitraturia may also be present.

SUMMARY

Patients with metabolic syndrome and those submitted to modern bariatric surgery are both at risk of nephrolithiasis and nephropathy. Accurate stone screening careful monitoring of renal function and diet counseling are strongly encouraged in these patients.

[A new approach to urinary stone analysis according to the combination of the components: experience with 7949 cases]

OBJECTIVE

To evaluate a new approach to urinary stone analysis according to the combination of the components.

MATERIALS AND METHODS

A total of 7949 stones were analysed and their main components and combinations of components were classified according to gender and age. Statistical analysis was performed using the chi-square test.

RESULTS

Calcium oxalate monohydrate (COM) was the most frequent component in both males (39%) and females (37.4%), followed by calcium oxalate dihydrate (COD) (28%) and uric acid (URI) (14.6%) in males and by phosphate (PHO) (22.2%) and COD (19.6%) in females (p=0.0001). In young people, COD and PHO were the most frequent components in males and females respectively (p=0.0001). In older patients, COM and URI (in that order) were the most frequent components in both genders (p=0.0001). COM is oxalate dependent and is related to diets with a high oxalate content and low water intake. The progressive increase in URI with age is related mainly to overweight and metabolic syndrome. Regarding the combinations of components, the most frequent were COM (26.3%), COD+Apatite (APA) (15.5%), URI (10%) and COM+COD (7.5%) (p=0.0001).

CONCLUSIONS

This study reports not only the composition of stones but also the main combinations of components according to age and gender. The results prove that stone composition is related to the changes in dietary habits and life-style that occur over a lifetime, and the morphological structure of stones is indicative of the aetiopathogenic mechanisms.

Diabetes and nephrolithiasis

Type 2 diabetes is associated with an increased risk of nephrolithiasis, specifically in the form of uric acid (UA) nephrolithiasis. Diabetic patients who produce uric stones exhibit a low urine pH, the key factor of UA crystallization. Production of such acidic urine appears to result from the insulin-resistant state characteristic of diabetes mellitus. Insulin resistance is also involved in the pathogenesis of primary UA nephrolithiasis observed in overweight subjects with the metabolic syndrome. Therefore, UA nephrolithiasis should be considered a possible manifestation of insulin resistance, as it already is for hyperuricemia. Occurrence of UA stones in a patient, especially if overweight or hypertensive, should prompt a search for components of the metabolic syndrome in order to implement therapeutic intervention aimed at preventing the development of type 2 diabetes and atherosclerotic complications. Reciprocally, diabetologists should be aware of the risk of UA stones in their patients.

Diabetes mellitus and the risk of urinary tract stones: a population-based case-control study

BACKGROUND

Because nephrolithiasis has been associated with obesity, an important risk factor for type 2 diabetes mellitus (DM), we tested the hypothesis that DM prevalence is increased in individuals who develop renal stones.

METHODS

In an initial electronic analysis, prior diagnoses of DM, hypertension, and obesity were compared between all Olmsted County, MN, residents with a diagnosis code for nephrolithiasis between 1980 and 1999 and matched residents of similar age and sex (N = 3,561 case-control pairs). A random sample of 260 cases and corresponding controls was selected for detailed medical record review to confirm and characterize the stone event and obtain heights, weights, blood pressures, and glucose and cholesterol values.

RESULTS

In the electronic analysis, unadjusted odds ratios (ORs) for DM (OR, 1.29; 95% confidence interval [CI], 1.09 to 1.53), obesity (OR, 1.15; 95% CI, 1.02 to 1.31), and hypertension (OR, 1.19; 95% CI, 1.04 to 1.35) were increased significantly for nephrolithiasis cases versus controls; DM remained significant after adjustment for age, sex, calendar year, hypertension, and obesity (OR, 1.22; 95% CI, 1.03 to 1.46). Detailed record review of a subset showed significant increases for cases versus controls for body mass index (OR, 1.05; 95% CI, 1.01 to -1.09) and hypertension (OR, 1.71; 95% CI, 1.17 to 2.59). Odds for DM were increased, but not significantly, in the subsample (OR, 1.44; 95% CI, 0.76 to 2.72). Among cases with stone analyses, those with uric acid stones (n = 10) had a greater percentage of DM compared with those with all other stone types (n = 112; 40% versus 9%; P = 0.02).

CONCLUSION

Findings from this population-based study suggest that DM, obesity, and hypertension are associated with nephrolithiasis, and DM may be a factor in the development of uric acid stones.

Type 2 diabetes increases the risk for uric acid stones

An increased prevalence of nephrolithiasis has been reported in patients with diabetes. Because insulin resistance, characteristic of the metabolic syndrome and type 2 diabetes, results in lower urine pH through impaired kidney ammoniagenesis and because a low urine pH is the main factor of uric acid (UA) stone formation, it was hypothesized that type 2 diabetes should favor the formation of UA stones. Therefore, the distribution of the main stone components was analyzed in a series of 2464 calculi from 272 (11%) patients with type 2 diabetes and 2192 without type 2 diabetes. The proportion of UA stones was 35.7% in patients with type 2 diabetes and 11.3% in patients without type 2 diabetes (P < 0.0001). Reciprocally, the proportion of patients with type 2 diabetes was significantly higher among UA than among calcium stone formers (27.8 versus 6.9%; P < 0.0001). Stepwise regression analysis identified type 2 diabetes as the strongest factor that was independently associated with the risk for UA stones (odds ratio 6.9; 95% confidence interval 5.5 to 8.8). The proper influence of type 2 diabetes was the most apparent in women and in patients in the lowest age and body mass index classes. In conclusion, in view of the strong association between type 2 diabetes and UA stone formation, it is proposed that UA nephrolithiasis may be added to the conditions that potentially are associated with insulin resistance. Accordingly, it is suggested that patients with UA stones, especially if overweight, should be screened for the presence of type 2 diabetes or components of the metabolic syndrome.

Diabetes mellitus and the risk of nephrolithiasis

BACKGROUND

Insulin resistance is a central feature of type 2 diabetes mellitus (DM) and may increase the risk of kidney stone formation. Existing cross-sectional data on the association between DM and nephrolithiasis are limited, and no prospective study to date has evaluated the relation between DM and the risk of kidney stones.

METHODS

To evaluate the relation between DM and prevalent kidney stones, we conducted a cross-sectional study of 3 large cohorts including over 200,000 participants: the Nurses' Health Study I (older women), the Nurses' Health Study II (younger women), and the Health Professionals Follow-up Study (men). We then prospectively studied the association between DM and incident nephrolithiasis over a combined 44 years of follow-up. Because insulin resistance can precede the diagnosis of DM by decades, we also prospectively examined the relation between kidney stones and the diagnosis of incident DM. Multivariate regression models adjusted for age, body mass index, thiazide diuretic use, fluid intake, and dietary factors.

RESULTS

At baseline, the multivariate relative risk of prevalent stone disease in individuals with DM compared to individuals without was 1.38 (95% CI 1.06-1.79) in older women, 1.67 (95% CI 1.28-2.20) in younger women, and 1.31 (95% CI 1.11-1.54) in men. Prospectively, the multivariate relative risk of incident kidney stone formation in participants with DM compared to participants without was 1.29 (95% CI 1.05-1.58) in older women, 1.60 (95% CI 1.16-2.21) in younger women, and 0.81 (95% CI 0.59-1.09) in men. The multivariate relative risk of incident DM in participants with a history of kidney stones compared to participants without was 1.33 (95% CI 1.18-1.50) in older women, 1.48 (95% CI 1.14-1.91) in younger women, and 1.49 (95% CI 1.29-1.72) in men.

CONCLUSION

DM is a risk factor for the development of kidney stones. Additional studies are needed to determine if the increased risk of DM in stone formers is due to subclinical insulin resistance.

Épidémiologie actuelle de la lithiase rénale en France

Nephrolithiasis is a frequent disease that affects about 10% of people in western countries. The prevalence of calcium oxalate stones has been constantly increasing during the past fifty years in France as well as in other industrialized countries. Stone composition varies depending to gender and age of patients and also underlines the role of other risk factors and associated pathologies such as body mass index and diabetes mellitus. The decrease in struvite frequency in female patients is the result of a significantly improved diagnostic and treatment of urinary tract infections by urea-splitting bacteria. In contrast, the increasing occurrence of weddellite calculi in stone forming women aged more than 50 years could be the consequence of post-menopausal therapy. A high prevalence of uric acid was found in overweight and obese stone formers and in diabetic ones as well. Another important finding was the increased occurrence with time of calcium oxalate stones formed from papillary Randall's plaques, especially in young patients. Nutritional risk factors for stone disease are well known: they include excessive consumption of animal proteins, sodium chloride and rapidly absorbed glucides, and insufficient dietary intake of fruits and potassium-rich vegetables, which provide an alkaline load. As a consequence, an excessive production of hydrogen ions may induce several urinary disorders including low urine pH, high urine calcium and uric acid excretion and low urine citrate excretion. Excess in calorie intake, high chocolate consumption inducing hyperoxaluria and low water intake are other factors, which favour excessive urine concentration of solutes. Restoring the dietary balance is the first advice to prevent stone recurrence. However, the striking increase of some types of calculi, such as calcium oxalate stones developed from Randall's plaque, should alert to peculiar lithogenetic risk factors and suggests that specific advices should be given to prevent stone formation.