Risk Factors For Stone Formation Research Articles

Клиническое значение применения препарата Канефрон® Н у больных МКБ после оперативного лечения

The drug Canephron N is a combination of extracts of centaury, lovage and rosemary. Moderate antispasmoic, anti-inflammatory, antioxidant, diuretic and antimicrobial effects are of great interest for urological practice. The optimal combination of components that were made of herbal medicine allows to use their synergistic effect for prevention of recurrence of urinary stone disease. The experience of using the drug Canephron in clinical practice is of great interest. to clarify the clinical efficiency of Canephron N in patients with urinary stone disease after surgical treatment and to evaluate the changes in diuresis and calcium excretion. The results of using the drug Canephron after surgical treatment of urinary stone disease are provided. The changes in diuresis and calcium excretion in 75 patients undergone surgical treatment of urinary stone disease were studied. Patients after ureteroscopy, percutaneous nephrolithotomy and extracorporeal shock-wave lithotripsy were prescribed treatment to prevent stone formation including herbal drug Canephron N. At baseline, there was negative correlation between 24-hours diuresis and calcium excretion in all groups. During follow-up, a positive correlation between 24-hours diuresis and calcium excretion was found in patients receiving Canephron N and other types of treatment. The average follow-up was 390 days. During this period, recurrence was noted in 1 patient receiving Canephron, 4 patients in patients who took other drugs and in 5 patients who didnt receive any treatment. Risk factors of stone formation persist after surgical treatment of urinary stone disease. This is reflected in a negative correlation between 24-hour diuresis and calcium excretion. During treatment, a positive correlation between diuresis and calcium excretion was noted in patients with urinary stone disease. The use of drugs that affect stone formation as well as herbal medicine Canephron N allow to obtain comparable ratio of diuresis and calcium excretion.

Assessment of conservative dietary management as a method for normalization of 24-h urine pH in stone formers.

Low urine pH is a metabolic risk factor for stone formation. While medical therapy is typically prescribed (as urinary alkalinization), patients typically prefer dietary modifications. We aimed to assess capacity to alter urine pH with dietary management alone. We analyzed a retrospective cohort of stone formers seen between 2000 and 2015 with multiple 24-h urine collections (24hUC). Patients ≥ 18years old with low urine pH (< 6.0) were included; those prescribed alkalinizing agents or thiazides were excluded. Demographic data, 24hUC parameters, and medications were abstracted. 24hUC was utilized to calculate gastrointestinal alkali absorption (GIAA). The primary outcome was urine pH ≥ 6.0 on second 24hUC. Predictors were selected utilizing multivariable logistic regression. The database consisted of 2197 stone formers; 224 of these met inclusion criteria. On second 24hUC, 124 (55.4%) achieved a favorable pH ≥ 6.0. On univariable analysis, a second pH ≥ 6.0 was associated with high initial pH, low initial sulfate, younger age, increase in citrate/GIAA/urine volume, and decrease in ammonium (P < 0.02). On multivariable analysis, high initial pH (OR = 23.64, P < 0.001), high initial GIAA (OR = 1.03, P = 0.001), lower initial sulfate (OR = 0.95, P < 0.001), increase in urine volume (OR = 2.19, P = 0.001), increase in GIAA (OR = 8.6, P < 0.001), increase in citrate (OR = 2.7, P = 0.014), decrease in ammonium (OR = 0.18, P < 0.001), and younger age (OR = 0.97, P = 0.025) were associated with a second pH ≥ 6.0. The analysis demonstrated a corrected AUC of 0.853. These data suggest that certain dietary recommendations (increases in urine volume, citrate, GIAA, and decreased acid load) may normalize urine pH in a select group of patients. This may allow urologists to counsel patients with low urine pH on possibility of success with dietary modification alone.

Risk Factors for Pancreatic Stone Formation in Type 1 Autoimmune Pancreatitis: A Long-term Japanese Multicenter Analysis of 624 Patients.

Autoimmune pancreatitis (AIP) has the potential to transform into chronic pancreatitis with pancreatic stone involvement. This retrospective investigation sought to clarify the risk factors for stone formation in type 1 AIP. Questionnaires on patients with type 1 AIP were sent to 22 high-volume medical centers across Japan to compare the clinical features of patients with and without pancreatic stone formation. Of the completed records on 624 type 1 AIP patients, 31 (5%) had experienced pancreatic stones. Median follow-up duration was 1853 days. Bentiromide test values at diagnosis were significantly lower, and hemoglobin A1c values after corticosteroid treatment were significantly higher in patients with pancreatic stones. Imaging results disclosed that pancreatic atrophy and hilar or intrahepatic bile duct stenosis were significantly more frequent in patients with pancreatic stone formation. Pancreatic head swelling tended to be more frequent in this group as well. On the other hand, a shorter follow-up period was associated with the nonformation of pancreatic stones. The increased frequency of pancreatic head swelling in type 1 AIP patients exhibiting pancreatic stones indicated a propensity for pancreatic juice stasis with subsequent stone development and pancreatic dysfunction occurring over longer periods of disease duration.

Obesity and stones.

The incidence of urolithiasis has shown a prominent increase in the last two to three decades and evidence-based data have clearly indicated the certain role of obesity and overweight in both children and adults. As a certain component of metabolic syndrome, 'obesity' has been found to have a significant impact on the urinary metabolic risk factors which may be important in stone formation. In this present review article, we aimed to evaluate the possible association between obesity and urolithiasis and related risk factors. The epidemiology, pathophysiology, and management of stone disease in obese cases will be discussed in detail. The possible influence of overweight/obesity on the metabolic stone-forming risk factors has been subjected to several studies which in turn well demonstrated the increased risk of stone formation in this population. Although the exact underlying mechanisms are still to be outlined, some certain pathogenetic factors, namely, changes in urinary pH and increased excretion of some urinary stone components have been well demonstrated. Given this increased risk status, these cases require a more comprehensive workup for urolithiasis. Appropriate metabolic evaluation-based medical therapy alongside dietary recommendations will be effective in preventing stone formation. Patients suffering from obesity problem have particular risk factors for urolithiasis when compared with their normal-weight counterparts. All efforts should be taken to increase the awareness of this problem and necessary precautions with well-planned treatment plan are the main tasks for urologists.

Cross-talk between renal lithogenesis and atherosclerosis: an unveiled link between kidney stone formation and cardiovascular diseases.

The prevalence of kidney stones and cardiovascular diseases (CVDs) are increasing throughout the world. Both diseases are chronic and characterized by accumulation of oxidized proteins and lipids in the renal tissue and arterial wall, respectively. Emerging studies have revealed a positive association between nephrolithiasis and CVDs. Based on preclinical and clinical evidences, this review discusses: (i) stone forming risk factors, crystal nucleation, aggregation, injury-induced crystal retention, and stone formation, (ii) CVD risk factors such as dyslipidemia, perturbation of gut microbiome, obesity, free radical-induced lipoprotein oxidation, and retention in the arterial wall, subsequent foam cell formation, and atherosclerosis, (iii) mechanism by which stone forming risk factors such as oxalate, calcium, uric acid, and infection contribute toward CVDs, and (iv) how CVD risk factors, such as cholesterol, phospholipids, and uric acid, contribute to kidney stone formation are described.

Минералогический состав камней, факторы риска и метаболические нарушения у пациентов с кальций-оксалатным уролитиазом

To identify the most likely metabolic disturbances and risk factors for stone formation in a group of patients with calcium oxalate urolithiasis, and to establish the relationship between the mineralogical composition of calculi and impaired excretion of inhibitors and promoters of stone formation. Fifty patients with calcium oxalate urolithiasis were tested using a complex of physicochemical methods. Patients assessment included evaluation of quantitative mineralogical composition of calculi, daily urine pH profile and daily urinary excretion of urates, calcium, magnesium, oxalate, phosphate and citrate ions. The main mineralogical phase of the stones in over 80% of patients was calcium oxalate monohydrate; none of the patients had pure dihydrate stones. The most frequent metabolic disorders were hypocitraturia, hypercalciuria and hyperuricosuria. Predominant risk factors were excessive body weight and insufficient fluid intake. Only one patient had an idiopathic stone formation. It was established for the first time that patients with calcium oxalate stones, containing 10 or more mass percent of apatites had statistically significantly lower daily urinary calcium and oxalate excretion and simultaneously increased phosphate excretion. The study findings showed that patients with calculi based on calcium oxalate dihydrate should undergo testing for daily urinary excretion of calcium and citrate while pa-tients with calcium oxalate stones containing 10 or more mass percent of apatites should also be tested for daily phosphate excretion and urine pH-profile. Daily urinary citrate excretion was reduced in all study patients, and urate excretion was significantly increased, apparently due to an imbalanced diet and excessive intake of animal protein. Menopausal and postmenopausal women are at a particular risk due to low urinary citrate excretion and high urinary calcium excretion regardless of stone composition.

Whey protein and albumin effects upon urinary risk factors for stone formation.

Protein supplements are consumed for an expected increase in muscle mass and improved exercise performance, but as their impact on lithogenic parameters are unknown, we aimed to evaluate the effects of Whey protein (WP) and Albumin upon the risk factors for nephrolithiasis. WP or Albumin supplements (one scoop/day) were administered for 3days to 18 healthy volunteers, with 1-week washout period between them. Serum and 24-h urine samples were collected at baseline and after completing each intervention. All participants were asked to replicate their baseline diet during the subsequent urine collection. After WP or albumin, mean protein equivalent of nitrogen appearance (PNA) was significantly higher (p < 0.001), as the result of the consumption of each of the supplements, but mean urinary calcium, phosphorus, sodium, potassium, uric acid, citrate, oxalate, magnesium, creatinine, pH, and urinary saturation indices did not differ from baseline. However, individual increases higher than 50% in urinary calcium were observed in 39% of the individuals and variable decreases in urinary pH in 44 and 67% of them, respectively, after WP or Albumin. Increases higher than 50% in urinary sodium occurred in one-third of them after Albumin. A short-term consumption of WP or albumin by healthy subjects, under controlled diet, did not significantly change the mean lithogenic parameters. Nevertheless, the wide individual variation and relevant increases/decreases observed for urinary calcium, sodium, and pH suggest the need of a closer surveillance of these parameters and adequacy of diet in case of supplementation by stone formers.

Preventive Kidney Stones: Continue Medical Education.

Nephrolithiasis is a common health problem across the globe with a prevalence of 15%–20%. Idiopathic hypercalciuria is the most common cause of nephrolithiasis, and calcium oxalate stones are the most common type of stones in idiopathic hypercalciuric patients. Calcium phosphate stones are frequently associated with other diseases such as renal tubular acidosis type 1, urinary tract infections, and hyperparathyroidism. Compared with flat abdominal film and renal sonography, a noncontrast helical computed tomography scan of the abdomen is the diagnostic procedure of choice for detection of small and radiolucent kidney stones with sensitivity and specificity of nearly 100%. Stones smaller than 5 mm in diameter often pass the urinary tract system and rarely require surgical interventions. The main risk factors for stone formation are low urine output, high urinary concentrations of calcium, oxalate, phosphate, and uric acid compounded by a lower excretion of magnesium and citrate. A complete metabolic workup to identify the risk factors is highly recommended in patients who have passed multiple kidney stones or those with recurrent disease. Calcium oxalate and calcium phosphate stones are treated by the use of thiazide diuretics, allopurinol, and potassium citrate. Strategies to prevent kidney stone recurrence should include the elimination of the identified risk factors and a dietary regimen low in salt and protein, rich in calcium and magnesium which is coupled with adequate fluid intake.

Gallstones in childhood: etiology, clinical features, and prognosis.

The aim of this study was to determine demographic and clinical features in children diagnosed with gallstones, risk factors for gallstone formation, the effectiveness of ursodeoxycholic acid therapy, and the course of the disease. Patients aged 0-18 years were followed up for at least 6 months after the diagnosis of gallstones with ultrasonography and were evaluated retrospectively. Patients were evaluated with respect to age, sex, presenting symptoms, BMI, facilitating factors, accompanying diseases, family history of gallstones, history of ceftriaxone use, laboratory tests, ultrasonography findings and follow-up, and therapeutic approaches and results. The study was completed with 70 patients. Thirty-nine (55.7%) patients were females. The mean age of the patients was 9.3±5.29 (0.3-18) years. The mean age among females was statistically significantly higher than that among males (P=0.007).No risk factor for stone formation was encountered in 50% of cases, whereas a family history of gallstones was present in 17.1%. Use of ceftriaxone was present in 8.6% of cases, total parenteral nutrition in 10%, obesity in 5.7%, hereditary spherocytosis in 4.3%, and Down's syndrome in 4.3%. The probability of dissolution of stones was 3.6 times higher in patients with stone sizes up to 5 mm [odds ratio (OR): 3.65, P=0.020], 3.9 times higher in those aged younger than 2 years (OR: 3.92, P=0.021), and 13.9 times higher in those with a single stone (OR: 13.97, P=0.003). Our findings show that unknown causes are still prevalent in stone formation and that ursodeoxycholic acid exerts no effect on stone dissolution; however, diagnosis at younger than 2 years of age, a single stone, and small size of stone are factors affecting dissolution.

Urolithiasis following urinary diversion.

Urolithiasis is a well-known occurrence after cystectomy and urinary diversion. With high incidence and recurrence rates of urolithiasis, complex anatomy and associated morbidities, these patients remain a management challenge for urologists. The purpose of this review is to examine the literature and consider the risk factors for stone formation in this group of patients and reflect on the reported outcomes with the range of available treatment options.

MP82-02 EVALUATION OF STUDENT ATHLETE KIDNEY STONE RISK VIA 24 HOUR URINE COLLECTION

You have accessJournal of UrologyStone Disease: Epidemiology & Evaluation I1 Apr 2016MP82-02 EVALUATION OF STUDENT ATHLETE KIDNEY STONE RISK VIA 24 HOUR URINE COLLECTION Katherine Theisen, Omar Ayyash, Matthew Ferroni, Kevin Rycyna, Julie Riley, Timothy Averch, and Michelle Semins Katherine TheisenKatherine Theisen More articles by this author , Omar AyyashOmar Ayyash More articles by this author , Matthew FerroniMatthew Ferroni More articles by this author , Kevin RycynaKevin Rycyna More articles by this author , Julie RileyJulie Riley More articles by this author , Timothy AverchTimothy Averch More articles by this author , and Michelle SeminsMichelle Semins More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.2143AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Dehydration is a known risk factor for kidney stone formation. High-caliber athletes who undoubtedly experience prolonged states of dehydration during competition and training do not have an apparent increased risk of stone events. We aimed to determine why athletes do not experience an increased incidence of nephrolithiasis. To do this we performed a study to evaluate urinary risk factors for kidney stone formation in student athletes utilizing 24 hour urine collections. METHODS After IRB and NCAA compliance office approval, thirty four student athletes (ages 19-22) were enrolled in and completed the study. Demographics, body mass index, medical and surgical history, medications, and specific sport were recorded. All participants collected at least one 24 hour urine specimen. Standard stone risk parameters were assessed. Summary statistics were calculated to define the normal trends for young adult athletes. Descriptive analyses were then performed comparing this population to standard normal lab values, including variations by gender. RESULTS The average age of the athletes was 20 years old with a median body mass index of 23.7. There were 16 females and 18 males in the study. Median urine volume was 1.46 liters with 68% of the subjects having volumes less than 2 liters. Median calcium excretion in females was 219 with 63% having abnormally high excretions compared to normal values. Uric acid excretion was high in 56% of male student athletes and 68% of all student athletes had high sodium excretion. Magnesium excretion was normal/high in 56% while citrate excretion was low in 59% of female subjects and 39% of male subjects. Over 90% of athletes had high excretion of creatinine per kilogram per 24 hours. All athletes had at least one risk factor for kidney stone formation, however, all male athletes and over 50% of female athletes also had one or more stone protective factors. CONCLUSIONS Student athletes appear to have a high prevalence of urinary risk factors for stone formation such as low volume, high calcium, high uric acid, high sodium, and low citrate. Overall stone risk in this population may be offset by increased levels of stone-protective factors such as magnesium. High muscle mass may be protective or at least a marker of decreased risk. These findings may potentially explain the lack of increased incidence of nephrolithiasis in athletes. Further study is needed. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e1073 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Katherine Theisen More articles by this author Omar Ayyash More articles by this author Matthew Ferroni More articles by this author Kevin Rycyna More articles by this author Julie Riley More articles by this author Timothy Averch More articles by this author Michelle Semins More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Kidney stones.

Kidney stones are mineral deposits in the renal calyces and pelvis that are found free or attached to the renal papillae. They contain crystalline and organic components and are formed when the urine becomes supersaturated with respect to a mineral. Calcium oxalate is the main constituent of most stones, many of which form on a foundation of calcium phosphate called Randall's plaques, which are present on the renal papillary surface. Stone formation is highly prevalent, with rates of up to 14.8% and increasing, and a recurrence rate of up to 50% within the first 5 years of the initial stone episode. Obesity, diabetes, hypertension and metabolic syndrome are considered risk factors for stone formation, which, in turn, can lead to hypertension, chronic kidney disease and end-stage renal disease. Management of symptomatic kidney stones has evolved from open surgical lithotomy to minimally invasive endourological treatments leading to a reduction in patient morbidity, improved stone-free rates and better quality of life. Prevention of recurrence requires behavioural and nutritional interventions, as well as pharmacological treatments that are specific for the type of stone. There is a great need for recurrence prevention that requires a better understanding of the mechanisms involved in stone formation to facilitate the development of more-effective drugs.

Hyperoxaluria: The role of N-acetyl-L-cysteine and Vitamin E on lithogenic factors and urinary markers in ameliorating calcium oxalate crystallization

Background and Aim: In hyperoxaluria, membrane injury is essential for the binding of oxalate or calcium oxalate (CaOx) crystal to be retained in the renal cell. This oxalate‑membrane interaction generates oxidative stress and is considered to be a significant causative factor of membrane damage and stone pathogenesis. The present study uses ammonium oxalate (AmOx) rat model to develop hyperoxaluria and lipid peroxidation, and N‑acetyl‑L‑cysteine (NAC) and NAC + Vitamin E given intraperitoneally to prevent CaOx crystal membrane damage and crystal binding. Methods: Stone forming risk factors namely, calcium, phosphate, oxalate, and inhibitors of stone formation namely, magnesium, uric acid, citrate, and glycosaminoglycans (GAGs) were studied and for renal function sodium, creatinine, and protein were seen in urine of five groups of animals (6 numbers each). The ratios of Ca/oxalate Mg/oxalate, citrate/calcium, oxalate/creatinine, and others are of clinical importance to assess the recurrence in stone formers. The CaOx supersaturation index and activity product (CaOx) index (rats) were studied as it indicates a high risk for stone formation. Further, the levels of oxalate synthesizing enzymes in liver and kidney were studied for endogenous synthesis of oxalate. Besides, urinary marker enzymes alkaline phosphatase, gamma glutamyl transferase, and lactate dehydrogenase (LDH) were studied indicating tissue membrane damage. Endogenous oxalate synthesizing enzymes of liver and kidney were done and also the tissue risk factors of stone. LDH isoenzyme gel electrophoresis and light microscopy of kidney tissue were done. Results: Urinary oxalate was increased significantly (P < 0.05) urinary calcium too, urinary magnesium was significantly decreased (P < 0.01), urinary citrate levels were found to be 1.43 ± 0.15 mg/24 h in control animals but decreased 3‑fold in AmOx‑treated animals. Urinary marker enzymes showed injured epithelium, a prerequisite for crystal adhesion and decreased GAGs in urine showed damage to the proximal convoluted tubules. LDH 2 isoenzyme as a marker of kidney tissue damage was found increased in hyperoxaluric rats. Levels of urinary GAGs were decreased significantly (P < 0.001). NAC and Vitamin E pretreated animals showed a significant decrease in stone forming risk factors in urine and increased inhibitor excretion. Histological sections showed NAC and Vitamin E pretreated hyperoxaluric rats inhibited deposition of CaOx crystals and renal cell damage. Conclusion: NAC therapy prevents CaOx retention by protecting against membrane injury, thus maintaining a smooth urothelium that does not favor stone formation.

Dietary recommendations and treatment of patients with recurrent idiopathic calcium stone disease.

This review describes the various dietary regimens that have been used to advise patients on how to prevent the recurrence of their calcium-containing kidney stones. The conclusion is that although there is some general advice that may be useful to many patients, it is more efficacious to screen each patient individually to identify his/her main urinary, metabolic, nutritional, environmental, and lifestyle risk factors for stone-formation and then tailor specific advice for that particular patient based on the findings from these investigations. If the patient can be motivated to adhere strictly to this conservative approach to the prophylactic management of their stone problem over a long time period, then it is possible to prevent them from forming further stones. This approach to stone management is considerably less expensive than any of the procedures currently available for stone removal or disintegration. In the UK, for each new stone episode prevented by this conservative approach to prophylaxis it is calculated to save the Health Authority concerned around £2000 for every patient treated successfully. In the long term, this accumulates to a major saving within each hospital budget if most stone patients can be prevented from forming further stones and when the savings are totalled up country-wide saves the National Exchequer considerable sums in unclaimed Sick Pay and industry a significant number of manpower days which would otherwise be lost from work. It is also of immense relief and benefit to the patients not to have to suffer the discomfort and inconvenience of further stone episodes.

Dietary treatment of urinary risk factors for renal stone formation. A review of CLU Working Group.

Dietary treatment of urinary risk factors for renal stone formation. A review of CLU Working Group.

Collection and Storage of Urine Specimens for Measurement of Urolithiasis Risk Factors

To evaluate how different methods for storage and preservation of urine samples affected the outcome of analysis of risk factors for stone formation. Spot urine samples were collected from 21 healthy volunteers. Each fresh urine sample was divided into ten 10-mL aliquots: 2 without preservative, 2 with thymol, 2 with toluene, 2 with hydrochloric acid (HCl), and 2 with sodium azide. One sample of each pair was stored at 4 °C and the other at room temperature. The concentrations of calcium, magnesium, sodium, phosphate, urate, oxalate, citrate, and pH in each urine sample were analyzed immediately after collection (0 hour) and after 24 and 48 hours. There were no significant differences in calcium, oxalate, magnesium, phosphate, sodium, urate or pH (without acidification) between samples with different preservation methods (P >.05). Urinary citrate, however, was significantly lower in the urine collected with HCl than when other preservatives were used, both at room temperature and at 4 °C. Urine pH was significantly higher after 48 hours than after 24 hours, whether the samples were stored at room temperature or at 4 °C. Antibacterial preservatives (eg, thymol or toluene) can be recommended as preservatives for 24-hour urine collections. Ideally, the samples should be stored at 4 °C. When HCl is used as a preservative, it seems essential to neutralize the samples before analysis. This is particularly obvious with the chromatographic method used for analysis of citrate that was used in this study.

Age-related prevalence of diabetes mellitus, cardiovascular disease and anticoagulation therapy use in a urolithiasis population and their effect on outcomes: the Clinical Research Office of the Endourological Society Ureteroscopy Global Study.

This study examined the prevalence of risk factors for urological stone surgery and their possible influence on outcome and complications following ureteroscopy (URS). The Clinical Research Office of the Endourological Society Ureteroscopy Global Study collected prospective data on consecutive patients with urinary stones treated with URS at centers around the world for 1 year. The prevalence of common comorbidities and anticoagulation therapy and their relationship with complications and age were examined. Of 11,719 patients, 2,989 patients (25.8%) had cardiovascular disease, including 22.6% with hypertension, and 1,266 patients (10.9%) had diabetes mellitus. Approximately six percent of patients were receiving oral anticoagulation therapy, including aspirin (3.7%) and clopidogrel (0.8%). The prevalence of hypertension and diabetes mellitus and the proportion of patients receiving anticoagulant medication and/or antidiabetes treatment increased with age. Elderly were more likely to develop a postoperative complication when they had diabetes, a cardiovascular disease or received anticoagulation therapy. Post-operative bleeding was higher in patients receiving anticoagulants than those not receiving them (1.1 vs. 0.4%; p < 0.01). Patients with risk factors for stone formation had more complications than those without (4.9 vs. 3.0%, p < 0.001). This is the first study confirming in a global population that URS can effectively and safely be performed in a population with high comorbidity. The risk of a complication was highest among elderly patients presenting with comorbidities.

Paediatrics: A 24 h urine collection is essential in nephrolithiasis evaluation.

Prevention of recurrent disease is the cornerstone of the management of paediatric nephrolithiasis and includes an evaluation to identify underlying causes or risk factors of stone formation. 24 h urine collection should be an initial step in the evaluation of the metabolic status of every child with urinary tract stones.

Enteric hyperoxaluria secondary to small bowel resection: use of computer simulation to characterize urinary risk factors for stone formation and assess potential treatment protocols.

We used computer modeling to investigate the influence of physicochemical stone risk factors on urinary supersaturation (SS) of calcium oxalate (CaOx) in patients with severe hyperoxaluria, relative hypocalciuria, hypocitraturia, and CaOx nephrolithiasis after extensive small bowel resection, usually performed for Crohn's disease. We also simulated different treatment strategies, including oral calcium supplements and citrate, in such patients. A baseline urine model was derived by consolidating data acquired by ourselves with those from another patient cohort. Calcium and oxalate excretions in this model were altered to obtain an extreme case. For comparison, additional models were based on published urine data from normal subjects (N) and idiopathic CaOx stone formers (SF). The Joint Expert Speciation System was used to simulate different urine situations based on reported compositional values. [Ca(2+)][Ox(2-)] ionic concentration products and SS(CaOx) are substantially higher in enteric hyperoxaluric patients than in N and SF, despite their relatively lower calcium excretions. Molar Ca:Ox ratios are substantially lower in enteric hyperoxalurics than in N and SF. Oral calcium supplements can reduce SS(CaOx), but monitoring is required to avoid exceeding a safe dosing threshold. A simple calculation can alert the clinician that this threshold is being approached or even exceeded. Increasing urinary pH and citrate decreases SS(CaOx) but not to the same extent as decreasing Ox excretion. Calcium supplements can help reduce stone risk in patients with severe enteric hyperoxaluria, but initial efforts should be directed toward reducing urinary oxalate by reducing dietary oxalate. Citrate therapy that increases both urine pH and urinary citrate provides an additional therapeutic benefit.

The Characteristics of the Stone and Urine Composition in Chinese Stone Formers: Primary Report of a Single-center Results

To assess urine composition in Chinese patients with urolithiasis. Five hundred seven Chinese patients with urolithiasis from our center in southern China were included in this study. Analysis of stone composition was performed using infrared spectrometry. From all patients, 24-hour urine samples were collected for analysis of urinary variables. Some ion activity product risk indices were also calculated. The major stone constituents in the 507 analyzed stones were as follows: calcium oxalate (78.3%), infection stone components (14.6%), uric acid (3.6%), and calcium phosphate (3.4%). Only 1 stone was composed of cystine (0.2%). Of all patients, 504 (99.4%) had 1 or several urinary metabolic abnormalities. Hypocitraturia was recorded in 93.9%, high sodium excretion in 58.6%, small urine volume in 45.6%, hyperoxaluria in 31.0%, hypercalciuria in 26.0%, hyperuricosuria in 19.3%, and hyperphosphaturia in 2.8%. Moreover, high sodium excretion was more frequent in men than women (59.2% vs 49.3%, P = .027), whereas hypercalciuria was more common in women (34.5% vs 20.4%, P <.001). High levels of urine sodium (187.7 ± 86.9 vs 179.8 ± 107.7 mmol/24h, P = .038) and phosphate (18.26 ± 8.36 vs 15.69 ± 11.14 mmol/24h, P <.001) were found in men than in women. Infection stones were significantly (P <.004) more common in women. Compared with noninfection stone formers, the occurrence of hypomagnesuria (P = .040) was more common in patients with infection stones. The results of urinary risk factors for stone formation in this study might serve as a basis for design of recurrence prevention. It is of interest to note that some of the demonstrated abnormalities differ from that in reports from other countries.