Incidence Of Nephrolithiasis Research Articles

Morbidity and Efficacy of Ureteroscopic Stone Treatment in Patients with Neurogenic Bladder

There is a lack of information on the safety and efficacy of ureteroscopy in the neurogenic bladder population. We hypothesized that ureteroscopy in patients with neurogenic bladder would be associated with an increased risk of complications and a lower stone clearance rate than in patients without neurological impairment. We reviewed a local registry of patients with ICD-9 codes for urolithiasis between 2004 and 2012. The study cohort was assembled from all eligible patients with neurogenic bladder and a randomly selected control group that had undergone ureteroscopy. Statistical analysis of demographic variables and surgical outcomes was performed. Complications were classified according to the Clavien system. Clearance was defined by computerized tomography, renal/bladder ultrasound or direct ureterorenoscopy. Ureteroscopy was performed a total of 173 times in 127 controls and a total of 45 times in 20 patients with neurogenic bladder. There was no difference between presenting episodes by gender (p = 1.0), race (p = 0.654) or body mass index (p = 0.519). Bacteriuria was associated with the stone episode in 16.4% of controls and 67% of neurogenic bladder cases (p <0.001). Median operative time was significantly longer in those with neurogenic bladder (80.5 minutes, IQR 50-110.5 vs 52, IQR 33-78, p = 0.0003). The proportion of complications was significantly different (p = 0.013). Stones cleared in 86.6% of controls compared to 63% of neurogenic bladder cases (p = 0.004). Patients with neurogenic bladder have increased morbidity after ureteroscopy for upper tract calculi compared to neurologically unaffected controls. Infection has a role in this morbidity. The clearance rate is lower but the stone burden is more significant in those with neurogenic bladder.

Risk factors for urinary stones in healthy schoolchildren with and without a family history of nephrolithiasis

The prevalence of lithiasis is increasing at all ages. This study aimed to assess the crystallization risk in urine from healthy school children and to determine urinary parameters that are most associated with it. Urine samples were obtained from 184 children aged 5-12 years: a spot sample collected in the afternoon, and a 12-h overnight sample. Information was obtained regarding family histories of lithiasis. Urine volume, pH, and biochemical parameters of stone risk were measured. Crystallization risk was defined by the presence of specific urine conditions that had previously been associated with stone formation in vitro. Crystallization risk was observed in 15 % of spot urine samples and 54 % of 12-h samples. Metabolic abnormalities and a low urinary volume were more frequently detected in children with crystallization risk. Calcium excretion and calcium/citrate ratio were higher in children with a family history of lithiasis. We observed a high prevalence of crystallization risk in urine, especially in children with a family history of the disease. Low urinary volume was the factor most associated with increased risk. Adequate fluid intake at an early age may be a simple and effective measure to reduce the incidence of nephrolithiasis.

The Effect of Restrictive Bariatric Surgery on Urolithiasis

Roux-en-Y gastric bypass (RYGB) surgery, a mixed malabsorptive/restrictive procedure, is associated with enteric hyperoxaluria and an increased risk of kidney stones. The incidence of nephrolithiasis after purely restrictive bariatric procedures such as adjustable gastric banding or sleeve gastrectomy has not been well described. We aim to analyze the incidence of kidney stones in patients who undergo either adjustable gastric banding or sleeve gastrectomy. In a retrospective study, we analyzed a pool of 332 patients who underwent adjustable gastric banding and 85 patients who underwent sleeve gastrectomy at the University of California, San Diego Center for the Treatment for Obesity within a 54-month period (September 2006 to February 2011). The primary outcomes of urinary calculus diagnosis and surgical treatment were investigated using manual chart review and International Classification of Diseases and Related Health Problems-9 code electronic search. Within the adjustable gastric banding cohort, we found a person-time incidence rate of 3.40 stone diagnoses per 1000 person-years. Within the sleeve gastrectomy cohort, we found a person-time incidence rate of 5.25 stone diagnoses per 1000 person-years. Questions remain whether purely restrictive bariatric procedures such as sleeve gastrectomy or adjustable gastric banding avoid the risk of kidney stones. Our study demonstrates a very low incidence of kidney stones after restrictive bariatric procedures, although larger sample sizes, longer follow-up times, and controlled prospective studies are necessary to validate this finding.

Urine risk factors in children with calcium kidney stones and their siblings

Calcium nephrolithiasis in children is increasing in prevalence and tends to be recurrent. Although children have a lower incidence of nephrolithiasis than adults, its etiology in children is less well understood; hence treatments targeted for adults may not be optimal in children. To better understand metabolic abnormalities in stone forming children, we compared chemical measurements and the crystallization properties of 24-hour urine collections from 129 stone formers matched to 105 non-stone forming siblings and 183 normal, healthy children with no family history of stones; all aged 6 to 17 years. The principal risk factor for calcium stone formation was hypercalciuria. Stone formers have strikingly higher calcium excretion along with high supersaturation for calcium oxalate and calcium phosphate, and a reduced distance between the upper limit of metastability and supersaturation for calcium phosphate, indicating increased risk of calcium phosphate crystallization. Other differences in urine chemistry that exist between adult stone formers and normal individuals such as hyperoxaluria, hypocitraturia, abnormal urine pH and low urine volume were not found in these children. Hence, hypercalciuria and a reduction in the gap between calcium phosphate upper limit of metastability and supersaturation are crucial determinants of stone risk. This highlights the importance of managing hypercalciuria in children with calcium stones.

The effects of ambient temperature, humidity and season of year on urine composition in patients with nephrolithiasis

Study Type--Prognosis (cohort series) Level of Evidence 2b. What's known on the subject? and What does the study add? Epidemiologic studies have shown that warmer climates are associated with increased incidence of nephrolithiasis. Many hypothesize that this is due to dehydration and lower urine volumes. The current study of stone formers reports that greater temperatures are associated with significant increases in urine calcium which may shed light on the mechanism underlying the increased stone incidence associated with increased ambient temperature. • To understand the effects of temperature, humidity and season of year on 24-h urine composition in patients with nephrolithiasis. • A retrospective review was performed of patients evaluated at four metabolic stone clinics. • Multivariate linear regression models examined the relationship between mean temperature, average humidity, season of year and 24-h urine composition. • Multivariate models adjusted for known risk factors for stone disease. • Mean temperature and average humidity data were obtained from http://www.weatherunderground.com based on patient-provided addresses. • A total of 599 patients were included in the study, comprising 239 women and 360 men with a mean age of 53.6 years (sd 15.0). • Mean temperature was 16.9 °C (sd 4.8, range -21.1 to 38.3 °C) and average humidity was 58.1% (sd 23.5, range 11-100%). • On multivariate linear regression, increasing temperature was associated with increasing urine calcium (β = 11.3, 95% CI 2.2-20.0), super-saturation of calcium oxalate (β = 0.6, 95% CI 0.2-0.9), super-saturation of calcium phosphate (β = 0.14, 95% CI 0.03-0.2), and decreasing urine sodium (β = -5.2, 95% CI -10.3 to -0.1). • As seasons become warmer (i.e. from winter to autumn to spring to summer), changes were increased urine volume (β = 0.09, 95% CI 0.01-0.2) and decreased super-saturation of calcium phosphate (β = -0.2, 95% CI -0.3 to -0.03). • There were no associations between quintile of humidity and any 24-h urine constituents. • Increasing temperature may increase stone risk by increasing urine excretion of calcium, and the super-saturation of calcium oxalate and calcium phosphate. • These findings were independent of humidity and of season of year. • This appears to be related to a physiological impact of temperature itself, rather than to geographic location.

Pathophysiology of Nephrolithiasis

The incidence of nephrolithiasis has risen over the last twenty years and continues to rise. Although it is often referred to as a disease, recent advances in the understanding of the pathophysiology suggest that it is a systemic disorder. We conducted a PubMed based literature review on the recent advances in the pathophysiology of kidney stone formation. There is a link between diabetes, metabolic syndrome, obesity, insulin resistance and nephrolithiasis. Along with the aging population and a Western diet, these are the main reasons for the rising incidence and prevalence of nephrolithiasis. Different theories as to the pathophysiological mechanisms of lithogenesis have been proposed, including the free and fixed particle theories, and Randal's plaque hypothesis. Among the different types of kidney stones, those containing calcium are the most common, followed by those containing uric acid, struvite and cystine. Supersaturated urine, acidic urine pH and reductions in kidney stone inhibitors in the urine are the main recognized causes that contribute to the formation of all these stone-types. Nephrolithiasis is considered a systemic pathology that may lead to end-stage renal disease. Although much progress has been made, the underlying pathophysiological mechanisms of kidney stone formation are still not fully understood.

Urine risk factors in children with calcium kidney stones and their siblings

Calcium nephrolithiasis in children is increasing in prevalence and tends to be recurrent. Although children have a lower incidence of nephrolithiasis than adults, its etiology in children is less well understood; hence, treatments targeted for adults may not be optimal in children. To better understand metabolic abnormalities in stone-forming children, we compared chemical measurements and the crystallization properties of 24-h urine collections from 129 stone formers matched to 105 non-stone-forming siblings and 183 normal, healthy children with no family history of stones, all aged 6 to 17 years. The principal risk factor for calcium stone formation was hypercalciuria. Stone formers have strikingly higher calcium excretion along with high supersaturation for calcium oxalate and calcium phosphate, and a reduced distance between the upper limit of metastability and supersaturation for calcium phosphate, indicating increased risk of calcium phosphate crystallization. Other differences in urine chemistry that exist between adult stone formers and normal individuals such as hyperoxaluria, hypocitraturia, abnormal urine pH, and low urine volume were not found in these children. Hence, hypercalciuria and a reduction in the gap between calcium phosphate upper limit of metastability and supersaturation are crucial determinants of stone risk. This highlights the importance of managing hypercalciuria in children with calcium stones.

Incidence of kidney stones with topiramate treatment in pediatric patients

We ran this study to assess the incidence of nephrolithiasis in a group of children on topiramate (TPM) therapy for at least 1 year. In this retrospective observational surveillance study, we reviewed the medical charts of children on TPM for at least 1 year seen at the pediatric neurology department during the period from 2005 to 2010 at King Fahad Medical City. Children with a normal baseline ultrasound report were included. Follow-up ultrasound reports after at least 1 year were collected. However, patients with any evidence of chronic illness or medications that may affect the kidney functions in addition to those who are not compliant with the prescribed dose were excluded. Family history of renal stones, symptoms suggestive of urologic disorders, and comorbidities were recorded. Medical charts of 96 children on TPM with a mean age of 6.9 (±3.8) years were reviewed; 52 (54.2%) of the children were male. The follow-up ultrasound showed that five children (5.2%) had developed kidney stones. The occurrence of kidney stones was found in four female patients (80%) versus one male (20%) (p > 0.05). Long-term use of TPM may result in increased incidence of asymptomatic kidney stones in the pediatric population. Hence, routine baseline and follow-up ultrasound of the urinary system should be recommended during the use of TPM in children.

An Update on the Changing Epidemiology and Metabolic Risk Factors in Pediatric Kidney Stone Disease

Nephrolithiasis in children is a painful and costly disease that may also have detrimental long-term effects on kidney function. Recent data provide evidence that the incidence of nephrolithiasis in children is rising. Children who are white, female, and adolescent seem to have the highest risk for forming symptomatic kidney stones. Although the reasons for the rising incidence and demographic discrepancies in pediatric nephrolithiasis are not yet clear, recent investigations into urine chemistry provide clues regarding predisposing metabolic risk factors. As more data emerge regarding epidemiologic and metabolic characteristics of pediatric kidney stone formers, we hope to gain a better understanding of the causes of kidney stone disease and, ultimately, provide better strategies for stone prevention in children.

Can Biochemical Abnormalities Predict Symptomatology in Patients with Primary Hyperparathyroidism?

Primary hyperparathyroidism presents with a myriad of symptoms, which range in severity. The cause of these symptoms is not well understood. We sought to determine if the severity of preoperative biochemical abnormalities (calcium, parathyroid hormone, vitamin D levels) correlated with symptomatology in patients undergoing surgical treatment for primary hyperparathyroidism. Over 15 months, 229 consecutive patients with primary hyperparathyroidism completed a symptom questionnaire before parathyroidectomy. The symptom profiles of patients with significant hypercalcemia at initial presentation (≥11.2 mg/dL) and those with baseline calcium levels (<11.2 mg/dL) were compared. The patients were also categorized based on parathyroid hormone (< or ≥130 pg/mL) and vitamin D (< or ≥30 ng/mL) and analyzed in a similar manner. Seventy-eight patients (34%) had a baseline calcium ≥11.2 mg/dL, but compared with patients with calcium <11.2 mg/dL, only the incidence of nephrolithiasis was more common in those patients with significant hypercalcemia (18% vs 9%, p = 0.04). Conversely, depression, bone or joint pain, and constipation were all significantly more common in patients with calcium <11.2mg/dL (p = 0.006, 0.001, and 0.031, respectively). Patients analyzed based on parathyroid hormone and vitamin D levels showed no significant difference in symptom presentation. These data indicate that the degree of parathyroid hormone elevation and the presence of vitamin D deficiency do not correlate with the presence of symptoms in patients with primary hyperparathyroidism. Significant hypercalcemia was associated with nephrolithiasis, but interestingly, patients with milder hypercalcemia had significantly more depression, bone or joint pain, and constipation, suggesting that these symptoms are likely not mediated by hypercalcemia.

Cost-Effectiveness of Primary Prevention Strategies for Nephrolithiasis

Stone disease is a highly prevalent condition associated with substantial cost and morbidity. We evaluated the cost-effectiveness of a primary prevention strategy. A decision analysis model was constructed to compare the cost of ad hoc management of symptomatic stones vs the cost of primary prevention. A literature search was performed to determine the incidence of stone disease, the effectiveness of nonmedical prevention strategies and cost associated with stone management. One and 2-way sensitivity analyses were performed to determine conditions under which a strategy of primary prevention might be cost-effective. Assuming a 1% incidence of stones, a 50% risk reduction and a $100 cost per individual per year for primary prevention, the model was used to calculate the overall costs per individual per year without and with a primary prevention strategy of $46 and $123, respectively. One-way sensitivity analyses indicated that primary prevention was cost-effective if the incidence of stones exceeded 4.3% yearly or the cost of prevention was less than $23 per person yearly. Varying other factors (risk reduction, probability of requiring surgery, hours of lost work, emergency room cost) failed to reach cost equivalence under any circumstances or required unrealistic assumptions. Preventive strategies were more costly than no prevention unless the incidence of stone disease was at least 1%, the cost did not exceed $20 per person per year and the prevention strategy was at least 50% effective in preventing stones. Primary prevention strategies for stone disease have not been sufficiently evaluated but can theoretically be cost-effective if the population has a sufficiently high incidence of stone disease and the strategy is of low cost and moderately effective.

A hierarchical Bayesian approach for risk assessment of melamine in infant formula based on cases of related nephrolithiasis in children

Although the 2008 outbreak of nephrolithiasis in children due to melamine-contaminated infant formula has subsided, it remains uncertain whether the present tolerable daily intake (TDI) of melamine provides sufficient protection for young children. To conduct a safety assessment for melamine in infant formula, we established a dose–response relationship based on 13 nephrolithiasis cases selected from 932 children, all of whom were under 5 years of age and had potentially been exposed to contaminated milk in China or Taiwan. According to the children's exposure history, distributions of individual daily melamine intake (mg/kg BW/day) were reconstructed using Monte Carlo simulations to account for uncertainties in exposure duration and melamine concentrations in the contaminated milk. Based on the simulated individual average daily intake (AVDI) of melamine, subjects were further classified into four separate AVDI groups: high, medium, low and a reference group. A statistical logistic model was then fitted for the dose–response relationship between nephrolithiasis incidence and daily melamine intakes using Markov chain Monte Carlo (MCMC) simulations. Based on the background exposure, spontaneous rate, and mode of action (MOA) of nephrolithiasis in children, the simulated lower bounds of the 95% CIs daily melamine intake ranged from 0.008 to 0.03 mg/kg BW/day corresponding to an additional risks of 0.1% is proposed as a plausible TDI, which is approximately an order lower than the current WHO-suggested TDI level of 0.2 mg/kg BW/day. More stringent regulations on melamine levels in infant formula should be considered to protect young children fully.

Lunar Tractive Forces and Renal Stone Incidence

Background. Several factors are implicated in renal stone formation and peak incidence of renal colic admissions to emergency departments (ED). Little is known about the influence of potential environmental triggers such as lunar gravitational forces. We conducted a retrospective study to test the hypothesis that the incidence of symptomatic renal colics increases at the time of the full and new moon because of increased lunar gravitational forces. Methods. We analysed 1500 patients who attended our ED between 2000 and 2010 because of nephrolithiasis-induced renal colic. The lunar phases were defined as full moon ± 1 day, new moon ± 1 day, and the days in-between as “normal” days. Results. During this 11-year period, 156 cases of acute nephrolithiasis were diagnosed at the time of a full moon and 146 at the time of a new moon (mean of 0.4 per day for both). 1198 cases were diagnosed on “normal” days (mean 0.4 per day). The incidence of nephrolithiasis in peak and other lunar gravitational phases, the circannual variation and the gender-specific analysis showed no statistically significant differences. Conclusion. In this adequate powered longitudinal study, changes in tractive force during the different lunar phases did not influence the incidence of renal colic admissions in emergency department.

Possible Relationship between Metabolic Syndrome Traits and Nephrolithiasis: Incidence for 15 Years According to Gender

PurposeTo analyze the independent effect of metabolic syndrome (MS) on nephrolithiasis (NL) despite differences in gender compared with the known lithogenic factors.Materials and MethodsFrom 1995 to 2009, 40,687 Koreans were enrolled in the study and observed for the development of NL at a health promotion center. The examination included anthropometric and biochemical measurements as well as kidney ultrasonography. A student's t-test or chi-square test was used to characterize the participants and a standard Cox proportional hazards model was used to calculate the adjusted odds ratio of lithogenic risk factors in the NL model.ResultsThe mean age of the study cohort was 44.9 years (range, 13-100 years), and 22,540 (55.4%) of the cohort was male. The incidence of NL was 1.5% (609 participants), with males exhibiting a higher incidence than females (1.9% vs 1.0%, p<0.01). Among the total cohort, MS as well as each trait of MS were risk factors for NL. In males, high body mass index (BMI), high blood pressure, and abnormal glucose metabolism were significant lithogenic factors, whereas in females, lithogenic factors included only high BMI and abnormal glucose metabolism.ConclusionsMS is a significant lithogenic factor compared with other lithogenic factors. There was a correlated change in the prevalence of MS and NL and MS traits in Korea.

Postmenopausal Hormone Use and the Risk of Nephrolithiasis

Observational studies examining the role of estrogen in the risk of kidney stone formation have shown conflicting results. However, randomized trial evidence on nephrolithiasis risk with estrogen therapy in postmenopausal women is lacking. We reviewed the incidence of nephrolithiasis in the Women's Health Initiative estrogen-alone and estrogen plus progestin trials conducted at 40 US clinical centers. A total of 10 739 postmenopausal women with hysterectomy were randomized to receive 0.625 mg/d of conjugated equine estrogens (CEE) or placebo, and 16 608 postmenopausal women without hysterectomy were randomized to receive placebo or estrogen plus progestin given as CEE plus medroxyprogesterone acetate (2.5 mg/d). The incidence of nephrolithiasis was determined for an average follow-up of 7.1 years for the CEE trial and 5.6 years for the estrogen plus progestin trial. Baseline demographic characteristics and risk factors for nephrolithiasis were similar in the placebo and treatment arms. Estrogen therapy was associated with a significant increase in nephrolithiasis risk from 34 to 39 cases per 10 000 person-years (hazard ratio, 1.21; 95% confidence interval, 1.03-1.44). Censoring data from women when they ceased to adhere to study medication increased the hazard ratio to 1.39 (95% confidence interval, 1.08-1.78). The increased nephrolithiasis risk was independent of progestin coadministration, and effects did not vary significantly according to prerandomization history of nephrolithiasis. These data suggest that estrogen therapy increases the risk of nephrolithiasis in healthy postmenopausal women. These findings should be considered in decision making regarding postmenopausal estrogen use. The mechanisms underlying this higher susceptibility remain to be determined. Trial Registration clinicaltrials.gov Identifier: NCT0000611.

Evening Primrose Oil Supplementation Increases Citraturia and Decreases Other Urinary Risk Factors for Calcium Oxalate Urolithiasis

We investigated the effects of gamma-linolenic acid (an omega-6 polyunsaturated fatty acid) in the form of evening primrose oil on calcium oxalate urinary stone risk factors in 2 ethnic groups. Eight black and 8 white healthy male subjects ingested 1,000 mg evening primrose oil (Natrodale, Kuils River, South Africa) daily for 20 days while following a free diet. Arachidonic acid content was determined by a dietary questionnaire. On days 0, 10 and 20, and 4 days after protocol 24-hour urine samples were collected. Samples were analyzed using routine assays. Citraturia increased significantly in each group. Urinary oxalate showed a tendency to decrease in black subjects. Calciuria and the Tiselius risk index decreased significantly in each group. Carryover effects were observed. To our knowledge increased citraturia has not been previously reported for any essential fatty acid. We hypothesize that evening primrose oil inhibits lipogenesis, thereby decreasing citrate consumption. For the decrease in oxaluria we suggest that evening primrose oil alters membrane fatty acid composition, thereby inhibiting the modulation of protein kinases that lead to hyperoxaluria. In regard to decreased calciuria we suggest that evening primrose oil modulates delta-5 and/or delta-6-desaturase, thereby inhibiting the production of arachidonic acid and prostaglandin E2, which influence calciuria. The different response in the 2 groups with respect to oxaluria confirms previously reported differences in sensitivity toward supplemental ingestion. Data suggest that evening primrose oil supplementation should be investigated as a possible conservative treatment for calcium oxalate urolithiasis.

Fructose intake as a risk factor for kidney stone disease

Taylor and Curhan report that consumption of fructose is independently associated with an increased risk of incident kidney stones. What could be the mechanisms underlying the relation between fructose intake and stone risk? And how should we incorporate this finding into the dietary advice that we give to our patients to prevent kidney stone formation?

DUCHENNE MUSCULAR DYSTROPHY IS AN INDEPENDENT RISK FACTOR FOR NEPHROLITHIASIS AMONG PATIENTS WHO HAVE ACHIEVED PROLONGED SURVIVAL THROUGH USE OF NONINVASIVE VENTILATION

PURPOSE: We previously described an unexpectedly high incidence of nephrolithiasis among patients (pts) with Duchenne muscular dystrophy (DMD) who achieved prolonged survival through use of noninvasive ventilation (NIV). This study assesses whether DMD was an independent risk factor for nephrolithiasis.

Admission for Nephrolithiasis in Pregnancy and Risk of Adverse Birth Outcomes

Nephrolithiasis occurring during pregnancy may be associated with an elevated risk of preterm delivery and other adverse birth outcomes. The goal of this study was to describe the association between these outcomes and admission for nephrolithiasis during pregnancy. We performed a retrospective cohort study using birth certificate records linked to Washington State hospital discharge data from 1987-2003 to compare pregnant women admitted for nephrolithiasis and randomly selected pregnant women without nephrolithiasis. The main outcomes of interest were preterm delivery, premature rupture of membranes at term or before 37 weeks of gestation, low birth weight, and infant death. A total of 2,239 women were admitted for nephrolithiasis, yielding a cumulative incidence of 1.7 admissions per 1,000 deliveries. Women admitted for nephrolithiasis during pregnancy had nearly double the risk of preterm delivery compared with women without stones (adjusted odds ratio 1.8, 95% confidence interval 1.5-2.1). However, they were not at higher risk for the other outcomes investigated. A total of 471 (25.9%) women had one or more procedures for kidney stones during prenatal hospitalization. Undergoing a procedure and the trimester of admission did not affect the risk of preterm delivery. Although the incidence of nephrolithiasis requiring hospital admission during pregnancy is relatively low, these women have an increased risk of preterm delivery. This has potential implications for counseling of pregnant women with kidney stones requiring hospital admission. Additionally, it may prompt definitive treatment of small, asymptomatic stones in women during reproductive years.

Ceftriaxone associated nephrolithiasis: a prospective study in 284 children

Urinary tract calculi have been reported to account for between 1 in 1,000 and 1 in 7,600 hospital admissions in children in the USA. The annual incidence of urolithiasis in patients older than 10 years is 109 per 100,000 of the population in men and 36 per 100,000 of the population in women in Minnesota. The use of various medications is considered to be one of the etiologic factors of nephrolithiasis. Ceftriaxone is a widely used third-generation cephalosporin that is generally considered very safe, but complications such as biliary pseudolithiasis, and rarely, nephrolithiasis have been reported in children. There is limited information about urolithiasis as a side effect of ceftriaxone. The aim of this study was evaluation of the incidence of nephrolithiasis following ceftriaxone therapy in children. This quasi-experimental before and after study was conducted in Mofid Children's Hospital between 2003 and 2005. All patients were treated with 75 mg/kg intravenous ceftriaxone. Diagnosis of pyelonephritis was based on standard criteria. The first renal ultrasonography was performed on the first or second day of admission and was repeated on the last day of treatment. We also evaluated complicated patients for the third time with renal ultrasonography 3 months after treatment. Stone-forming patients underwent metabolic kidney stone risk factor evaluation. We evaluated 284 patients with pyelonephritis, 185 girls and 99 boys. The first ultrasonography was normal in all of our patients. On the second ultrasonography renal stones were reported in 4 out of 284 cases (1.4% and CI=0.96-1.83%). Underlying metabolic risk factors could not be identified in stone-forming patients. Follow-up ultrasonography 3 months later was normal. The results of our study suggest that ceftriaxone-treated patients may be at an increased risk of kidney stone formation. Stones passed spontaneously in all affected patients so the use of this effective drug can be safely continued. Close monitoring of ceftriaxone-treated patients with regard to kidney stone formation is recommended.