Studies on the prevalence and epidemiology of urinary stone disease in men in Leeds

Urolithiasis and water intake in Saudi Arabia, is it a matter of quality or quantity?

Introduction:

Methods:

Results:

Conclusion:

The Demographic Diversity of Food Intake and Prevalence of Kidney Stone Diseases in the Indian Continent

Food intake plays a pivotal role in human growth, constituting 45% of the global economy and wellbeing in general. The consumption of a balanced diet is essential for overall good health, and a lack of equilibrium can lead to malnutrition, prenatal death, obesity, osteoporosis and bone fractures, coronary heart diseases (CHD), idiopathic hypercalciuria, diabetes, and many other conditions. CHD, osteoporosis, malnutrition, and obesity are extensively discussed in the literature, although there are fragmented findings in the realm of kidney stone diseases (KSD) and their correlation with food intake. KSD associated with hematuria and renal failure poses an increasing threat to healthcare infrastructures and the global economy, and its emergence in the Indian population is being linked to multi-factorial urological disorder resulting from several factors. In this realm, epidemiological, biochemical, and macroeconomic situations have been the focus of research, even though food intake is also of paramount importance. Hence, in this article, we review the corollary associations with the consumption of diverse foods and the role that these play in KSD in an Indian context.

Does quality of drinking water matter in kidney stone disease: A study in West Bengal, India

Purpose

The combined interaction of epidemiology, environmental exposure, dietary habits, and genetic factors causes kidney stone disease (KSD), a common public health problem worldwide. Because a high water intake (>3 L daily) is widely recommended by physicians to prevent KSD, the present study evaluated whether the quantity of water that people consume daily is associated with KSD and whether the quality of drinking water has any effect on disease prevalence.

Materials and Methods

Information regarding residential address, daily volume of water consumption, and source of drinking water was collected from 1,266 patients with kidney stones in West Bengal, India. Drinking water was collected by use of proper methods from case (high stone prevalence) and control (zero stone prevalence) areas thrice yearly. Water samples were analyzed for pH, alkalinity, hardness, total dissolved solutes, electrical conductivity, and salinity. Average values of the studied parameters were compared to determine if there were any statistically significant differences between the case and control areas.

Results

We observed that as many as 53.6% of the patients consumed <3 L of water daily. Analysis of drinking water samples from case and control areas, however, did not show any statistically significant alterations in the studied parameters. All water samples were found to be suitable for consumption.

Conclusions

It is not the quality of water, rather the quantity of water consumed that matters most in the occurrence of KSD.

Nephrolithiasis as a Risk Factor for CKD: The Atherosclerosis Risk in Communities Study

BACKGROUND AND OBJECTIVES

Previous studies demonstrated a higher risk of CKD in persons with a history of kidney stones, but these studies examined mostly white populations and did not evaluate important potential interactions such as race and plasma uric acid.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In 10,678 Atherosclerosis Risk in Communities (ARIC) study participants free of CKD at baseline (ARIC visit 4 in 1996-1998), we assessed the association between a history of nephrolithiasis (a time-varying variable, defined by a combination of self-report and diagnostic codes) and incident CKD (defined by diagnostic codes from linkage to hospitalizations and US Centers for Medicare and Medicaid Services' records).

RESULTS

At baseline, 856 participants had a history of nephrolithiasis; 322 developed nephrolithiasis during follow-up. Over a mean follow-up of 12 years, there were 1037 incident CKD events. Nephrolithiasis history was associated with a 29% (hazard ratio [HR], 1.29; 95% confidence interval [95% CI], 1.07 to 1.54) higher risk of CKD in demographic-adjusted analyses, but the association was no longer statistically significant after multivariable adjustment (HR, 1.09; 95% CI, 0.90 to 1.32). The multivariable-adjusted association was stronger among participants with plasma uric acid levels ≤6 mg/dl (HR, 1.34; 95% CI, 1.05 to 1.72) compared with those with levels >6 mg/dl (HR, 0.94; 95% CI, 0.70 to 1.28; P(interaction) = 0.05). There was no interaction of stone disease and race with incident CKD.

CONCLUSIONS

In this community-based cohort, nephrolithiasis was not an independent risk factor for incident CKD overall. However, risk of CKD was unexpectedly elevated in participants with stone disease and lower plasma uric acid levels.

Does hypertension impact 24-hour urine parameters in patients with nephrolithiasis?

OBJECTIVE

To examine the differences in 24-hour urine parameters and stone composition between patients with and without systemic hypertension (HTN) in a large cohort of stone formers.

MATERIALS AND METHODS

We performed a retrospective review over a 10-year period of patients with stone, who had completed a 24-hour urinalysis (Litholink) and for whom demographic information was available, including the presence of HTN. Univariate and multivariate analyses were performed, comparing the 24-hour urinalysis profiles of patients with HTN with that of normotensive patients.

RESULTS

Of the 1115 patients eligible for inclusion, 442 patients (40%) had HTN and 673 (60%) did not. Patients with HTN were significantly older, had a higher body mass index, and had a greater number of comorbid conditions than normotensive patients. Univariate analysis revealed significantly lower urine pH, calcium, supersaturation (SS) of calcium oxalate (CaOx) and SS calcium phosphate (all P <.05) in patients with HTN. Multivariate analysis showed significantly lower calcium, citrate, and SS CaOx in patients with HTN (all P <.05).

CONCLUSION

Our results demonstrate lower levels of calcium and SS CaOx on univariate and multivariate analysis, as well as lower levels of citrate on multivariate analysis in patients with HTN. These results suggest that lower levels of citrate may contribute to stone formation to a greater degree in patients with HTN than abnormalities in calcium metabolism.

Renal diseases in adults with cystic fibrosis: a 40 year single centre experience

BACKGROUND

There is a sizable literature describing renal disease in patients with cystic fibrosis. Previous studies have focused on single disease processes alone, most commonly renal stone disease or acute kidney injury. In this study we report for the first time on the prevalence of all forms of renal disease in a cystic fibrosis population.

METHODS

A retrospective review of adult patients with cystic fibrosis attending the Adult Cystic Fibrosis Department at the Royal Brompton Hospital was carried out by searching the department's database to identify patients with renal problems and subsequently retrieving clinical information from medical notes.

RESULTS

The prevalence of all renal diseases in our population was 5.1 %. The most commonly identified problem was renal stones. At 2.0 % the prevalence of renal stones in adult patients with cystic fibrosis was comparable to the general population. A range of other renal diseases were identified, the next most common being drug-induced acute kidney injury.

CONCLUSIONS

A range of cystic fibrosis independent and attributable diseases has been identified but no cystic fibrosis specific disease. In contrast to other cystic fibrosis centres no increased prevalence of renal stones was found.

Clinical and metabolic evaluation of patients with history of renal calculi in Qazvin, Iran

BACKGROUND

Nephrolithiasis is a common clinical disorder with significant health and economic burden. We conducted this study to evaluate clinical and metabolic parameters in adult patients with history of renal calculi.

MATERIALS AND METHODS

A total of 213 patients with history of nephrolithiasis participated in this study. Evaluation included the measurement of serum calcium, uric acid, parathormone, renal function tests, urinalysis, and urinary tests for cystinuria. Also, parameters such as volume, creatinine, calcium, uric acid, citrate, and oxalate levels were measured on 24-h urine. All patients underwent urinary tract system sonography.

RESULTS

Of total patients, 52% were males and 48% females. The mean age was 45.16 ± 13.16 years. Also, 51.2% of subjects had positive family history of nephrolithiasis. The mean body mass index was (26.8 ± 4.2) kg/m(2). The mean 24-h urine biochemical profiles were volume (1,748 ± 860 ml), Ca (183 ± 115), uric acid (544 ± 220), citrate (490 ± 351), and oxalate (17.1 ± 15.3) mg/day; urine calcium to creatinine ratio (0.15 ± 0.10) mg/mg, and urine calcium to weight ratio (2.4 ± 1.7) mg/kg. While there were weak positive correlations between the body mass index and urinary calcium (r = 0.101, P < 0.001) and uric acid (r = 0.200, P < 0.001), a weak negative correlation with urine pH (r = -0.104, P < 0.001) was found.

CONCLUSIONS

Urine calcium, uric acid, and oxalate excretion were low in our patients while urine citrate was relatively high. Higher BMI maybe a risk factor for nephrolithiasis.

Considerations in minimally invasive surgery for renal and ureteric calculi: a bicenter quality control study

BACKGROUND

The use of minimally invasive surgery is increasing. Evaluating the quality of care brings new sights in the optimization of operating techniques.

METHODS

We included all procedures performed in two hospitals during 2010 and 2011. A total of 264 patients were included in the ureterorenoscopy (URS) group and 77 patients in the percutaneous nephrolitholapaxy (PCNL) group. Data were gathered by retrospectively reviewing medical records.

RESULTS

Mean stone diameter in the URS group was 9 mm. Patients suffered from a single stone in 79% of the cases. Calculi in the distal ureter, defined as the part of the ureter below the lower border of the sacroiliac joint, were most likely to be removed. A stone-free status was reached in 69% of the cases using URS. Mean stone diameter in the PCNL group was 23 mm. PCNL was successful in 70% of the cases in Haga Hospital versus 53% in Medisch Centrum Haaglanden. Incidence of complications was comparable between the hospitals (p = 0.5). Outcome and quality of both PCNL and URS was not influenced by sex, age or body mass index.

CONCLUSION

The clinical results were comparable with results in the literature. Further improvement can be made by optimization of technical aspects and centralization of treatment by urologists experienced in minimally invasive techniques.

The relationship of obesity and gender prevalence changes in United States inpatient nephrolithiasis

OBJECTIVE

To review the Nationwide Inpatient Sample database to examine the relationships between obesity, gender, and nephrolithiasis. Recent reports indicate that the prevalence of nephrolithiasis has been increasing, especially among women.

METHODS

The Nationwide Inpatient Sample contains data on approximately 20% of hospital stays in the United States. Included in this analysis were discharges with primary diagnosis ICD-9 codes 592.0 (renal calculus) or 592.1 (ureteral calculus), from 1998 through 2003. All raw data were weighted to produce national estimates. Descriptive and inferential statistics were performed to determine changes in nephrolithiasis prevalence and associations of obesity and other comorbidities with nephrolithiasis.

RESULTS

We reviewed 181,092,957 hospital stays (weighted data). The prevalence of nephrolithiasis was relatively stable: 0.52% (149,302) in 1998 and 0.47% (147,541) in 2003. The prevalence of obesity increased from 3.06% (878,155) to 4.99% (1,575,247). The male:female ratio of patients with stones decreased from 1.6:1 to 1.2:1. Multivariate analysis revealed a statistically significant relationship (OR = 1.22, 95% CI 1.20-1.23, P <.001) between obesity and urinary stones. Obese females were more likely to develop stones than nonobese females (OR = 1.35, 95% CI 1.33-1.37, P <.001). The association between obesity and stones was weaker in males (OR = 1.04, 95% CI 1.02-1.06, P <.001).

CONCLUSION

In this sample of inpatients, obesity was associated with a significantly increased prevalence of urinary stones. This relationship was stronger in females than in males. Further studies are needed to determine whether weight reduction in obese patients affects urinary stone disease.

Causes of autonomic dysfunction in idiopathic recurrent kidney stone formers

BACKGROUND

A higher prevalence of hypertension and adverse cardiovascular outcomes has been reported in kidney stone formers (KSF). We performed this study with the purpose of evaluating the autonomic nervous system (ANS) activity in KSF.

METHODS

We performed a 70° head-up tilt test in 30 idiopathic recurrent KSF aged 45.6 ± 12.1 years old (17 men: 13 women) and 30 healthy controls aged 42.0 ± 12.4 years old (17 women: 13 men). Thirteen KSF were hypertensive, and 17 were normotensive. Blood pressure (BP) and heart rate variability (HRV) were used for the non-invasive assessment of the efferent activity of the ANS. Discrete wavelet transform (DWT) was used to quantify the low-frequency (LF: 0.04-0.15 Hz) and high-frequency (HF: 0.15-0.4 Hz) components during several periods of tilt.

RESULTS

The results showed significantly higher HR and BP in KSF, in both supine and tilt positions. DWT revealed diminished HRV in the kidney stone patients during head-up tilt, with no increase in the LF and greater decrease in the HF components. The differences in the HF component of HRV were associated with obesity and hyperuricosuria, but the abnormalities of the LF component were independent of the explanatory variables. The LF component of systolic BP was significantly higher in KSF and was associated with hypertension.

CONCLUSIONS

Several factors may contribute to the presence of autonomic dysfunction in patients with recurrent nephrolithiasis. This abnormality has significant implications in cardiovascular risk assessment and treatment planning.

Recent advances in the pathophysiology of nephrolithiasis

Over the past 10 years, major progress has been made in the pathogenesis of uric acid and calcium stones. These advances have led to our further understanding of a pathogenetic link between uric acid nephrolithiasis and the metabolic syndrome, the role of Oxalobacter formigenes in calcium oxalate stone formation, oxalate transport in Slc26a6-null mice, the potential pathogenetic role of Randall's plaque as a precursor for calcium oxalate nephrolithiasis, and the role of renal tubular crystal retention. With these advances, we may target the development of novel drugs including (1) insulin sensitizers; (2) probiotic therapy with O. formigenes, recombinant enzymes, or engineered bacteria; (3) treatments that involve the upregulation of intestinal luminal oxalate secretion by increasing anion transporter activity (Slc26a6), luminally active nonabsorbed agents, or oxalate binders; and (4) drugs that prevent the formation of Randall's plaque and/or renal tubular crystal adhesions.

Nephrolithiasis as a systemic disorder

PURPOSE OF REVIEW

Nephrolithiasis is a prominent public health issue. It imposes a substantial burden on human health and is a considerable financial expenditure for the nation. Numerous epidemiologic studies have shown a significant association between nephrolithiasis, obesity, hypertension and chronic kidney disease. The review highlights many of those emerging studies and sheds light on the importance of our recognition of kidney stones as a systemic illness.

RECENT FINDINGS

Several cross-sectional retrospective studies have investigated the relationship between kidney stones and the metabolic syndrome. The various silent features of the metabolic syndrome, including type 2 diabetes, increased BMI, hypertension and dyslipidemia, are becoming progressively more recognized and independently associated with an increased risk of kidney stone formation.

SUMMARY

Our further understanding of the underlying mechanisms in the connection between nephrolithiasis and the metabolic syndrome will stimulate the development of more effective preventive and therapeutic measures.

Increased acid excretion in kidney stone formers with essential hypertension

BACKGROUND

Although several studies have reported that kidney stone disease and hypertension are associated, the link between the two conditions has not been identified. This study investigated urinary excretion of different solutes, particularly citrate and acids, in kidney stone formers and examined their association with high blood pressure.

METHODS

The retrospective study included 234 consecutive subjects, aged 47.0 +/- 15.6, attending our metabolic clinic after episodes of kidney stones. Essential hypertension was present in 82 patients (35.0%). A difference in the urinary excretion of some of the investigated components was found between subjects with normal blood pressure and those with hypertension.

RESULTS

The results showed that hypertensive subjects were older and had a higher body mass index (BMI) and serum uric acid. They had a significantly lower urinary pH (5.6 +/- 0.4 versus 6.0 +/- 0.5) and citrate (2.55 +/- 1.36 versus 2.83 +/- 1.65 mmol/24 h), higher titratable acid (38.8 +/- 19.0 versus 26.8 +/- 15.0 mEq/24 h) and ammonium (41.6 +/- 17.6 versus 34.2 +/-12.4 mmol/24 h). Logistic regression analysis with the presence of hypertension as the dependent variable produced a model with the following predictors: age (P < 0.0001), BMI (P = 0.026), titratable acid (P = 0.025) and low urinary citrate level (P = 0.033). Urinary acid excretion increased with the stage of hypertension. No difference was found in the urinary excretion of other solutes.

CONCLUSIONS

These findings suggest that essential hypertension and acid excretion are linked in stone formers.

Lithiasis and Risk Factors

Nephrolithiasis is a worldwide disease with high clinical and economic costs. The increasing incidence in industrialized countries seems to be related to several risk factors, which are partly inherited and partly acquired. Although risk factors in urolithiasis are still under discussion, their identification would provide a notable gain for the patient in terms of stone episodes, and for the health service in terms of costs. This article presents an easy classification of risk factors based on clinical background.

Diabetes mellitus and hypertension associated with shock wave lithotripsy of renal and proximal ureteral stones at 19 years of followup

PURPOSE

SWL has revolutionized the management of nephrolithiasis and it is a preferred treatment for uncomplicated renal and proximal ureteral calculi. Since its introduction in 1982, conflicting reports of early adverse effects have been published. However, to our knowledge the long-term medical effects associated with SWL are unknown. We evaluated these adverse medical effects associated with SWL for renal and proximal ureteral stones.

MATERIALS AND METHODS

Chart review identified 630 patients treated with SWL at our institution in 1985. Questionnaires were sent to 578 patients who were alive in 2004. The response rate was 58.9%. Respondents were matched by age, sex and year of presentation to a cohort of patients with nephrolithiasis who were treated nonsurgically.

RESULTS

At 19 years of followup hypertension was more prevalent in the SWL group (OR 1.47, 95% CI 1.03, 2.10, p = 0.034). The development of hypertension was related to bilateral treatment (p = 0.033). In the SWL group diabetes mellitus developed in 16.8% of patients. Patients treated with SWL were more likely to have diabetes mellitus than controls (OR 3.23, 95% CI 1.73 to 6.02, p <0.001). Multivariate analysis controlling for change in body mass index showed a persistent risk of diabetes mellitus in the SWL group (OR 3.75, 95% CI 1.56 to 9.02, p = 0.003). Diabetes mellitus was related to the number of administered shocks and treatment intensity (p = 0.005 and 0.007).

CONCLUSIONS

At 19 years of followup SWL for renal and proximal ureteral stones was associated with the development of hypertension and diabetes mellitus. The incidence of these conditions was significantly higher than in a cohort of conservatively treated patients with nephrolithiasis.

Epidemiological trends in urolithiasis: impact on our health care systems

The progressive increase of the social cost for treating urolithiasis could be related to an increased incidence of the disease and/or to an increase of costs for diagnosing and treating renal stones. In the course of the last century, the incidence of renal stones has progressively increased in Europe, North America, and other industrialised countries. This has been explained in terms of changing social conditions and the consequent changes in eating habits. In contrast, renal stones were less frequent than in developing countries of the world but in the last 20 years investigators began to report high incidences of upper urinary stone disease also from some areas of the Third World concurring with the changing of economic and social conditions. Each stone episode involves the costs for emergency visits, diagnostic work up, and medical or surgical treatment. Furthermore, we have to consider the costs of follow-up visits and the costs of testing and drugs for stone prevention. In adjunct of direct costs for diagnosis and treatment, we should also take into account the indirect individual and social cost of workdays lost. Finally, we should estimate the costs of complications and outcomes of treatment with particular attention to the costs of chronic renal failure secondary to stone disease. The strategy of treatment of each stone centre involves different costs for the treatment of each single stone episode. On the other hand the choice of treatment can be driven by National Health Systems and insurance companies by their policy of reimbursement for different procedures. The trends of renal stone incidence will have different impact on health care systems in different countries. In Europe and North America, the peak of incidence has been probably reached but the increase of costs for diagnosing and treating each single stone episode will still increase the social cost for managing stone disease. For this reason the actual objective should be to optimise protocols avoiding redundant or expensive diagnostic procedures or inappropriate treatments. In developing countries, the incidence of stone disease is still increasing and it could reach peaks even higher as a consequence of hot climate in some geographical areas. In those countries the demand for treatment of symptomatic stones could dramatically increase involving a huge financial outlay.

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.

Genetics of hypercalciuria and calcium nephrolithiasis: from the rare monogenic to the common polygenic forms

Idiopathic calcium nephrolithiasis is a multifactorial disease with a pathogenesis that involves a complex interaction of environmental and individual factors. This review discusses what is known about monogenic renal calcium stone-related disorders, provides an update on genetic research in calcium nephrolithiasis and such intermediate phenotypes as idiopathic hypercalciuria, discusses the problems that these conditions pose to clinicians and geneticists interested in their pathogenesis, and proposes some method tools potentially useful in this research frame of reference.

Metabolic assessment in patients with urinary lithiasis

INTRODUCTION

Metabolic investigation in patients with urinary lithiasis is very important for preventing recurrence of disease. The objective of this work was to diagnose and to determine the prevalence of metabolic disorders, to assess the quality of the water consumed and volume of diuresis as potential risk factors for this pathology.

PATIENTS AND METHODS

We studied 182 patients older than 12 years. We included patients with history and/or imaging tests confirming at least 2 stones, with creatinine clearance > or = 60 mL/min and negative urine culture. The protocol consisted in the collection of 2, 24-hour urine samples, for dosing Ca, P, uric acid, Na, K, Mg, Ox and Ci, glycemia and serum levels of Ca, P, Uric acid, Na, K, Cl, Mg, U and Cr, urinary pH and urinary acidification test.

RESULTS

158 patients fulfilled the inclusion criteria. Among these, 151 (95.5%) presented metabolic changes, with 94 (62.2%) presenting isolated metabolic change and 57 (37.8%) had mixed changes. The main disorders detected were hypercalciuria (74%), hypocitraturia (37.3%), hyperoxaluria (24.1%), hypomagnesuria (21%), hyperuricosuria (20.2%), primary hyperparathyroidism (1.8%), secondary hyperparathyroidism (0.6%) and renal tubular acidosis (0.6).

CONCLUSION

Metabolic change was diagnosed in 95.5% of patients. These results warrant the metabolic study and follow-up in patients with recurrent lithiasis in order to decrease the recurrence rate through specific treatments, modification in alimentary and behavioral habits.

Idiopathic calcium oxalate urolithiasis: risk factors and conservative treatment

Idiopathic calcium oxalate urolithiasis is a frequent and recurrent multifactorial disease. This review focuses on urinary and dietary risk factors for this disease and conservative strategies for rectifying them. Dietary oxalate and calcium and their respective urinary excretions have been extensively investigated during the last 10 years. Urinary oxalate has emerged as the most important determinant of calcium oxalate crystallization while the role of urinary calcium has shifted to bone balance and osteoporosis. Dietary calcium restriction increases urinary oxalate and contributes to a negative bone balance. It has therefore been abandoned as a means to reduce the risk of calcium oxalate kidney stone formation. Calcium oxalate kidney stone patients are advised to increase their fluid intake to achieve a urine volume of 2 l or more; the recommended calcium intake is 800-1200 mg/day; high oxalate foods should be restricted; daily protein intake should be between 0.8 and 1 g/kg body weight/day; essential fats should be included; vegetable and fruit (except oxalate-rich vegetables) intake should be increased. The use of calcium supplements has potential benefits but needs to be examined further.

Association of vitamin D receptor genotypes with calcium excretion in nephrolithiatic subjects in northern India

Our objective was to investigate the association between the vitamin D receptor (VDR) allelic variants (Bsm I and Fok I) and nephrolithiasis in northern India. A total of 150 nephrolithiatic patients and 100 age and sex matched controls were enrolled for study. A 10 ml blood sample was obtained for biochemical analysis and DNA isolation. In addition, 24 h urine samples were obtained from each patient for the estimation of calcium and creatinine. PCR was performed for the Bsm I and Fok I VDR variants. The association between Bsm I and Fok I VDR polymorphism and nephrolithiasis was investigated after digestion with restriction enzymes (3 U). The product was analysed on 3% agarose gel for Bsm I and 15% polyacrylamide gel for Fok I allelic variants. We did not observe any significant differences in the prevalence of either the Bsm I or Fok I VDR genotypes between stone formers and controls. The B allele was found to be more prevalent in hypercalciuric patients compared to controls and nephrolithiatic subjects. The subjects with the bb genotype exhibited a higher calcium excretion than the BB genotype. Patients with the F allele were also found to excrete higher urinary calcium. VDR genotypes may be associated with increased calcium excretion in hypercalciuric nephrolithiatic subjects.

Metabolic investigation of patients with urolithiasis in a specific region

OBJECTIVE

To assess the prevalence of the main metabolic alterations found in patients with recent diagnosis of urolithiasis in the West region of Parana state, Brazil.

MATERIALS AND METHODS

We made a retrospective study on 425 patients with evidence of recent formation of renal stones. Laboratory assessment consisted in 3 samples of 24-hour urine with dosing of calcium, uric acid, citrate, oxalate, sodium and creatinine. A urine culture was also made and qualitative cystinuria and urinary pH following 12-hour fasting and water restriction were evaluated.

RESULTS

In 96.5% of patients a cause was detected for the urolithiasis. Metabolic alterations most frequently found were: hypercalciuria (38.3%), hypocitraturia (29.6%) and hyperexcretion of uric acid (21.6%). Low urinary volume (17.9%), urinary tract infection (12.9%), hyperparathyroidism (3.3%), renal tubular acidosis (1.2%), cystinuria (0.9%) and anatomical alterations (12.7%) were also observed.

CONCLUSIONS

Hypercalciuria, hypocitraturia and hyperuricuria are the most frequent metabolic disorders in the population under study and these data are in accordance to the literature.

Risk factors for urinary tract calculi in Trinidad

OBJECTIVE

To identify risk factors for urinary tract stones in Trinidad and Tobago.

METHODS

A consecutive series of patients presenting to institutions in Trinidad for the management of proven urinary tract calculi was interviewed by questionnaires designed to obtain data on age, gender, ethnicity, occupation, stone location, a family history of stone disease, a past history of certain medical diseases and a semiquantitative estimate of the magnesium intake in food, 'over the counter' drugs and drinking water. An equivalent number of patients attending the same institutions for follow-up and verified from hospital records as having a previous radiological diagnosis of urinary tract stones, as well as a group of asymptomatic members of the community working in the same area, underwent the same interview. Chi-square, anova and Kruskal-Wallis tests were used to examine differences between the groups. Multiple logistic regression analysis was used to determine persistence of the significance of these differences after controlling for confounding variables.

RESULTS

Data sufficient for analysis were obtained for 122 previous and 102 prospective patients and 102 controls. The mean age of the patients was 32 years. The ratio of males to females was 0.9-1.8:1 for the affected groups, but significantly more males than females had calculi in the lower urinary tract (19%vs. 6%; P = 0.004). More patients (30%) than controls (7%) gave a positive family history of urinary tract stone disease (P < 0.001). Affected persons had a lower dietary magnesium intake (P = 0.003), which accounted for a significantly lower total magnesium intake (P = 0.02). Logistic regression analysis of the variables studied indicated that independent predictors of the disease were a positive family history (P = 0.001), total magnesium intake (P = 0.001) and age (P < 0.001).

CONCLUSION

A low magnesium intake and a positive family history are highly predictive of urinary tract calculi in this population.

Urine stone risk factors in nephrolithiasis patients with and without bowel disease

BACKGROUND

The prevalence of nephrolithiasis among patients with bowel disease is higher than in the general population. We examined urine stone risk factors and clinical characteristics of these patients, contrasted with a large group of stone forming patients without systemic disease.

METHODS

A total of 180 patients with bowel disease were compared with a group of 2048 nephrolithiasis patients with calcium or uric acid stones and without systemic diseases. Bowel diseases included inflammatory bowel disease with and without bowel resections, bowel resections from cancer or trauma, and bypass procedures for obesity or hypercholesterolemia. Urine stone risk factors, stone rates, stone compositions, and creatinine clearance were measured.

RESULTS

Compared to ordinary stone forming patients, bowel patients formed stones higher in rate of recurrence and in uric acid content. Uric acid content was highest when colon surgery had occurred. Urine volumes were low among all bowel patients except those with a bypass. Average creatinine clearance values were low among all bowel patients. Urine oxalate excretion was modestly elevated after small bowel resection, but very high with bypass. Supersaturations were increased mainly by low urine volume and-for uric acid-low pH. Patients with no surgery were indistinguishable from routine stone formers.

CONCLUSIONS

Low urine volume and pH are the main stone-forming abnormalities in bowel disease patients. Hyperoxaluria is extreme after bypass, but only modest after small bowel surgery. In the absence of surgery, bowel disease patients with stones cannot be distinguished from common stone formers by comprehensive stone risk measurements.

Pathophysiology of uric acid nephrolithiasis

Humans although a predominantly ureotylic organism, has preserved the ability to excrete nitrogen as uric acid and ammonia. An imbalance between these two secondary modes of nitrogen excretion has resulted in uric acid precipitation in human urine. Uric acid nephrolithiasis can arise from diverse etiologies all with distinct underlying defects converging to one or more of three defects of hyperuricosuria, acidic urine pH, and low urinary volume, originating from secondary, genetic or heretofore undefined (idiopathic) causes. A subset of idiopathic uric acid nephrolithiasis (gouty diathesis) may be the "tip of the icebergp" of a broader systemic illness characterized by insulin resistance. A novel renal manifestation of insulin resistance is a mild defect in ammonium excretion, which is not severe enough to disturb acid-base homeostasis, but is sufficient to set up the chemical milieu for uric acid nephrolithiasis.

Nephrolithiasis and osteoporosis associated with hypophosphatemia caused by mutations in the type 2a sodium-phosphate cotransporter

BACKGROUND

Epidemiologic studies suggest that genetic factors confer a predisposition to the formation of renal calcium stones or bone demineralization. Low serum phosphate concentrations due to a decrease in renal phosphate reabsorption have been reported in some patients with these conditions, suggesting that genetic factors leading to a decrease in renal phosphate reabsorption may contribute to them. We hypothesized that mutations in the gene coding for the main renal sodium-phosphate cotransporter (NPT2a) may be present in patients with these disorders.

METHODS

We studied 20 patients with urolithiasis or bone demineralization and persistent idiopathic hypophosphatemia associated with a decrease in maximal renal phosphate reabsorption. The coding region of the gene for NPT2a was sequenced in all patients. The functional consequences of the mutations identified were analyzed by expressing the mutated RNA in Xenopus laevis oocytes.

RESULTS

Two patients, one with recurrent urolithiasis and one with bone demineralization, were heterozygous for two distinct mutations. One mutation resulted in the substitution of phenylalanine for alanine at position 48, and the other in a substitution of methionine for valine at position 147. Phosphate-induced current and sodium-dependent phosphate uptake were impaired in oocytes expressing the mutant NPT2a. Coinjection of oocytes with wild-type and mutant RNA indicated that the mutant protein had altered function.

CONCLUSIONS

Heterozygous mutations in the NPT2a gene may be responsible for hypophosphatemia and urinary phosphate loss in persons with urolithiasis or bone demineralization.

Prevalence and epidemiologic characteristics of urolithiasis in Seoul, Korea

OBJECTIVES

To study the epidemiologic details of urolithiasis in Seoul, Korea. The prevalence of urolithiasis varies by different regions in the world and has been reported to be 4% to 15%.

METHODS

A total of 2643 persons 40 to 79 years old living in Seoul were selected by stepwise random sampling. Questionnaires were used and completed by trained interviewers concerning whether the subjects had experienced urinary stone disease at any time in their life.

RESULTS

Of 2643 persons interviewed, 65 experienced 78 episodes of urinary stone formation in their lifetime. Calibrated after the Seoul population census, the overall standardized lifetime prevalence rate was estimated to be 3.5%, 6.0% in men and 1.8% in women. The point prevalence rate was estimated to be 0.9%, 1.9% in men and 0.3% in women. Most of the urinary stone diseases were diagnosed at the fifth decade. Kidney stones in family members were present in 8.1% of patients with stones and 4.1% of stone-free control individuals. Twenty percent of the patients with stones experienced recurrences.

CONCLUSIONS

In this first systematically assessed epidemiologic survey about the rate of urolithiasis in Korea, 6.0% of Korean men and 1.8% of women are expected to experience urinary stone disease during their lifetime.

A family-based study of metabolic phenotypes in calcium urolithiasis

BACKGROUND

A family history increases the risk of kidney stone passage independent of dietary risk factors. However, the metabolic basis for familial aggregation of urolithiasis is unknown.

METHODS

We evaluated metabolic risk factors in families with at least two sibs with a history of calcium stones. Sibs underwent outpatient evaluations simultaneously, including 24-hour urine collection and oral calcium loading. Phenotypes were compared between affected and unaffected sibs from the same sibship.

RESULTS

Eighty-three sibships comprising 388 sibs (212 affected sibs, 114 males and 98 females, and 176 unaffected sibs, 68 males and 108 females) from 71 families were analyzed. Daily urine calcium excretion was higher in affected compared with unaffected sibs (0.64 +/- 0.33 vs. 0.50 +/- 0.22 mmol Ca(2+)/mmol creatinine, respectively, P < 10(-5)). This corresponded to absolute values of 7.4 +/- 3.9 and 5.1 +/- 2.3 mmol Ca(2+)/day, respectively, for affected and unaffected males, and 5.4 +/- 2.6 and 4.2 +/- 1.9 mmol Ca(2+)/day, respectively, for affected and unaffected female sibs. When analyzed by tertile of onset age of stone passage, the differences in urine calcium were only significant in the first two tertiles (with onset age of stone passage <35 years). The fasting urine Ca(2+)/creatinine ratio was significantly higher in stone formers compared with control sibs (0.46 +/- 0.27 vs. 0.40 +/- 0.27, P = 0.04), as was the postcalcium load Ca(2+)/creatinine ratio (0.57 +/- 0.46 vs. 0.43 +/- 0.41, respectively, P = 0.02). Body mass index was marginally significantly higher in stone forming sibs (P = 0.04). Other urine phenotypes, including oxalate, phosphate, magnesium, citrate, urate, sodium, ammonium, and volume, were not associated with stone passage.

CONCLUSION

Increased urine calcium excretion is the only phenotype associated with a kidney stone formation in these French-Canadian families.

[Epidemiology of urinary lithiasis]

An epidemiological study of urinary stone disease has been carried out in the districts of La Sierra and Hellín (Albacete, Spain). Between January 1992 and December 1999 a total of 887 patients with urinary lithiasis have been studied, analysing the number of patients discharged from hospital with the primary diagnosis of lithiasis, the distribution of lithiasis by area, age, gender, family history of lithiasis, diet, occupation and concurrent pathology. The geographical, geological, and climatic conditions, the composition of the water supply and the clinical characteristics are described. The incidence of urinary lithiasis in the whole area in 2.66 per thousand inhabitants/year, showing a male predominance with a male:female ratio of 1.26:1. The mean age was 51.34 years (bimodal distribution with peaks in the 4th and 7th decades). 20.41% of the patients had a family history, with the father being the most frequently affected relation. Those occupations associated with a sedentary life style or with a hot, dry workplace show a higher incidence of lithiasis. A hot, dry climate favours the formation of urinary lithiasis and the highest incidence of lithiasis is in the summer, during the months of July and August. No statistically significant influence was shown between at the hardness of the water and the incidence of urinary lithiasis in the study population.

Evaluation of the calcium-sensing receptor gene in idiopathic hypercalciuria and calcium nephrolithiasis

BACKGROUND

Calcium urolithiasis is in part genetically determined and associated with idiopathic hypercalciuria.

METHODS

We have used a candidate gene approach to determine whether the calcium-sensing receptor (CaR) gene is linked to idiopathic hypercalciuria and calcium urolithiasis in a cohort of French Canadian sibships with multiple affected members (64 sibships from 55 pedigrees yielding 359 affected sibling pairs with > or =1 stone episode).

RESULTS

Using nonparametric linkage analysis with various intragenic and flanking markers, we showed that the CaR gene could be excluded as a major gene for hypercalciuric stone formation. We excluded the CaR (lod score <-2) at lambdas values of 1.5, 1.68, and 2.6 for sib pairs concordant for at least one stone passage, at least two stone passages, and at least one stone passage and calciuria above the 75th percentile, respectively. Quantitative trait linkage analyses did not suggest that the CaR gene was linked to biochemical markers of idiopathic hypercalciuria.

CONCLUSIONS

This study shows that genetic variants of the CaR gene are not associated with idiopathic hypercalciuria and calcium nephrolithiasis in this population of French Canadians.

Essential arterial hypertension and stone disease

BACKGROUND

Cross-sectional studies have shown that nephrolithiasis is more frequently found in hypertensive patients than in normotensive subjects, but the pathogenic link between hypertension and stone disease is still not clear.

METHODS

Between 1984 and 1991, we studied the baseline stone risk profile, including supersaturation of lithogenic salts, in 132 patients with stable essential hypertension (diastolic blood pressure of more than 95 mm Hg) without stone disease and 135 normotensive subjects (diastolic blood pressure less than 85 mm Hg) without stone disease who were matched for age and sex (controls). Subsequently, both controls and hypertensives were followed up for at least five years to check on the eventual formation of kidney stones.

RESULTS

Baseline urine levels in hypertensive males were different from that of normotensive males with regards to calcium (263 vs. 199 mg/day), magnesium (100 vs. 85 mg/day), uric acid (707 vs. 586 mg/day), and oxalate (34.8 vs. 26.5 mg/day). Moreover, the urine of hypertensive males was more supersaturated for calcium oxalate (8.9 vs. 6.1) and calcium phosphate (1.39 vs. 0.74). Baseline urine levels in hypertensive females were different from that of normotensive females with regards to calcium (212 vs. 154 mg/day), phosphorus (696 vs. 614 mg/day), and oxalate (26.2 vs. 21.7 mg/day), and the urine of hypertensive females was more supersaturated for calcium oxalate (7.1 vs. 4.8). These urinary alterations were only partially dependent on the greater body mass index in hypertensive patients. During the follow-up, 19 out of 132 hypertensive patients and 4 out of 135 normotensive patients had stone episodes (14.3 vs. 2.9%, chi-square 11.07, P = 0.001; odds ratio 5.5, 95% CI, 1.82 to 16.66). Of the 19 stone-former hypertensive patients, 12 formed calcium calculi, 5 formed uric acid calculi, and 2 formed nondetermined calculi. Of the urinary factors for lithogenous risk, those with the greatest predictive value were supersaturation of calcium oxalate for calcium calculi and uric acid supersaturation for uric acid calculi.

CONCLUSIONS

A significant percentage of hypertensive subjects has a greater risk of renal stone formation, especially when hypertension is associated with excessive body weight. Higher oxaluria and calciuria as well as supersaturation of calcium oxalate and uric acid appear to be the most important factors. Excessive weight and consumption of salt and animal proteins may also play an important role.

Suggestive evidence for a susceptibility gene near the vitamin D receptor locus in idiopathic calcium stone formation

Calcium is the principal crystalline constituent in up to 80% of kidney stones. Epidemiologic studies have suggested that genetic predisposition plays a major role in the etiology of this condition. This study evaluates by a candidate-gene approach whether the vitamin D receptor (VDR) locus on chromosome 12q12-14 is implicated in idiopathic hypercalciuria and calcium nephrolithiasis in a cohort of 47 French Canadian pedigrees. These comprised 54 sibships with a total of 303 pairs of siblings concordant for > or =1 stone episode. Evidence is provided for linkage to nephrolithiasis with microsatellite marker D12S339 (near the VDR locus, P = 0.01), as well as with flanking markers (D12S1663: P = 0.03 and D12S368: P = 0.01). Inclusion of unaffected sibs in the analyses also supported evidence for linkage. Quantitative trait linkage analysis of urinary calcium excretion yielded linkage to some, but not all, markers. This appears to be the first study to suggest linkage for idiopathic calcium stone formation.

New onset hypertension after extracorporeal shock wave lithotripsy: age related incidence and prediction by intrarenal resistive index

PURPOSE

In a recent study we found an increased resistive index immediately after extracorporeal shock wave lithotripsy (ESWL) in patients older than 60 years, which suggests renovascular disturbance. The present 26-month followup study was undertaken to investigate the relevance of elevated resistive index levels and the incidence of new onset hypertension.

MATERIALS AND METHODS

Of the initial 76 patients 57, including 20 of the 23 at risk patients 60 or greater years, group 3), were followed for more than 26 +/- 6 months after ESWL. Followup included 2 resistive index measurements by Doppler ultrasound of the treated and the contralateral kidney, at least 2 blood pressure measurements 1 week apart and excretory urography as well as determination of plasma renin activity in 9 patients.

RESULTS

With 1 exception, elevated resistive index levels and hypertension were observed exclusively in patients older than 60 years. In these patients the resistive index ranged between 0.65 and 0.86 (mean plus or minus standard deviation 0.74 +/- 0.05, normal less than 0.7). This increase in resistive index was statistically significant (p < 0.0001). Compared to the levels obtained immediately after ESWL, the resistive index continued to increase in all 9 patients older than 60 years who had hypertension (45%), whereas in the normotensive patients the resistive index was either stable or decreased. There was a strong positive correlation (0.903) between pathological resistive index levels and blood pressure.

CONCLUSIONS

Patients older than 60 years are at risk for disturbances of renal perfusion as assessed by the resistive index, and 45% of these patients have new onset hypertension within 26 months of treatment.

Current aspects of epidemiology and nutrition in urinary stone disease

Current examples for the development of urinary stone disease are discussed by means of data from the literature and our own studies. Urinary stone disease has gained increasing significance due to changes in living conditions, i.e., industrialization and malnutrition. Changes in prevalence and incidence, the occurrence of stone types and stone location, and the manner of stone removal are explained. The importance of nutrition in the prevention of calcium oxalate stone disease is discussed in terms of fluid intake, calcium and oxalate metabolism, and dietary fat intake. The results of a study on a standardized mixed diet or an ovo-lactovegetarian diet show that well-balanced nutrition with consecutive high intake of fluids leads to a significant decrease in the risk for urinary stone formation (calculated as relative supersaturation with calcium oxalate by the computer program EQUIL).

Prevalence of urolithiasis in Kaizuka City, Japan--an epidemiologic study of urinary stones

BACKGROUND

According to the results of nationwide surveys, the prevalence of urolithiasis has been steadily increasing in Japan. However, these surveys relied on hospital statistics, and there has been no survey of the prevalence of urolithiasis in Japan utilizing postal questionnaires. We surveyed the prevalence of urolithiasis among the inhabitants of Kaizuka City.

METHODS

A total of 3,000 inhabitants ranging from 20 to 59 years old were randomly selected from the census register in numbers consistent with the population distribution of each district and sex by municipal computerized system.

RESULTS

A total of 1,975 postal questionnaires were returned, and 1,972 (65.7%) were considered valid. Of the respondents, 137 (6.95%) had a history of stones (men; 9.64%, women; 4.51%). The annual incidence of urolithiasis for Kaizuka citizens aged from 20 to 59 years old in 1991 was 0.97%, and the lifetime prevalence of urolithiasis increased linearly with age, and it was 10.3% for respondents in their 50s. In the total survey population of 7,568, which included the respondents and their family members, 342 (4.52%) had a history of stones. Male administrative workers had a significantly higher prevalence than any other occupational group. The monthly expenditure on food by the families of stone formers was significantly greater than that by the families of non-stone formers.

CONCLUSION

Extrapolation of the findings suggests that > 10% of the general population (> 13% of men and > 7% of women) can be expected to suffer from urolithiasis at least once in their lifetime.

Epidemiology of urinary stone disease in the Balearic Islands Community

In a survey conducted on 1500 individuals, an overall prevalence of 14.3% for the year 1990 was found for urinary stone disease in the Balearic Islands. The prevalence showed higher figures for people living in rural areas than for those living in cities, and this could be correlated with traditional living habits such as traditional Balearic diet. Finally, a surprising fact is that only 54% had consulted a urologist as outpatients and the rare occasion at which the calculi were analyzed (15.1%).

Hot occupation and nephrolithiasis

We investigated the prevalence of stone disease and urinary stone risk factors in machinists chronically exposed to a hot environment and massive sweating, without interference of nephrotoxic metals or other lithogenic compounds. The study was performed at a glass plant and exposure to heat stress was estimated by the Wet Bulb Globe Temperature climatic index. The prevalence of nephrolithiasis on the entire population of the machinists was 8.5% (20 of 236), while the prevalence on the controls working in normal temperature was 2.4% (4 of 165) (p = 0.03). A high incidence (38.8%) of uric acid stones was present in the workers exposed to heat stress. Among the urinary stone risk indexes determined for 3 days during the 8-hour work shift on a randomly selected sample of 21 workers exposed and 21 workers not exposed to heat stress without any evidence of stone disease significant differences were found in uric acid concentration (722 +/- 195 versus 482 +/- 184 mg./l., p < 0.001), specific gravity (1,026 +/- 4 versus 1,021 +/- 6, p < 0.005) and pH (5.31 +/- 0.28 versus 5.64 +/- 0.54, p < 0.02), respectively. Thus, high uric acid relative supersaturation was present during occupation in hot temperatures (8.67 +/- 3.49) compared to occupation in normal temperatures (4.15 +/- 2.7) (p < 0.001). This study confirms that chronic dehydration represents a real lithogenic risk factor, mainly for uric acid stones, and adequate fluid intake is recommended during hot occupations.

Kidney stones and hypertension: population based study of an independent clinical association

OBJECTIVE

To test the hypothesis that kidney stone disease is more frequent among hypertensive men when the effect of possible confounders is allowed for.

DESIGN

Cross sectional study of a sample of the male working population conducted as part of the 10 year follow up of a nationwide survey of the prevalence of cardiovascular risk factors.

SETTING

The Olivetti factory in Pozzuoli, a suburban area of Naples.

POPULATION

688 Male workers (87.9% of the male workforce) aged 21-68.

INTERVENTIONS

Anthropometric and blood pressure measurements, blood tests, and administration of a detailed questionnaire aimed at detecting a history of urolithiasis.

MAIN OUTCOME MEASURES

Prevalence of a history of urolithiasis among normotensive and untreated and treated hypertensive men adjusted for the possible confounding effects of age, body mass index, renal function, and serum urate and total calcium concentrations.

RESULTS

Of the 688 participants 509 were normotensive. Of the remainder, 118 had untreated and 61 treated hypertension. The overall prevalence of a history of urolithiasis was 16.3% (112/688). The relative risk of hypertensive subjects having a history of kidney stones was twice that of the normotensive group (odds ratio 2.11; 95% confidence interval 1.17 to 3.81), the risk being higher when only treated hypertensives were considered (odds ratio 3.16; 95% confidence interval 1.75 to 5.71). The prevalence of a history of urolithiasis was 13.4% (68/509) in the normotensive subjects, 20.3% (24/118) in the untreated hypertensives, and 32.8% (20/61) in the treated hypertensives (p less than 0.001). The age adjusted relative risk in treated hypertensive men was higher than that in the normotensive group (Mantel-Haenszel pooled estimate of odds ratio 2.63; 95% confidence interval 2.23 to 3.10).

CONCLUSION

An independent clinical association exists between the occurrence of urolithiasis and hypertension. The increased urinary calcium excretion commonly detected in hypertension may be the pathogenetic link.