Infection and urinary stones

Integrative genome-wide analyses identify novel loci associated with kidney stones and provide insights into its genetic architecture

Kidney stone disease (KSD) is a complex disorder with high heritability and prevalence. We performed a large genome-wide association study (GWAS) meta-analysis for KSD to date, including 720,199 individuals with 17,969 cases in European population. We identified 44 susceptibility loci, including 28 novel loci. Cell type-specific analysis pinpointed the proximal tubule as the most relevant cells where susceptibility variants might act through a tissue-specific fashion. By integrating kidney-specific omics data, we prioritized 223 genes which strengthened the importance of ion homeostasis, including calcium and magnesium in stone formation, and suggested potential target drugs for the treatment. The genitourinary and digestive diseases showed stronger genetic correlations with KSD. In this study, we generate an atlas of candidate genes, tissue and cell types involved in the formation of KSD. In addition, we provide potential drug targets for KSD treatment and insights into shared regulation with other diseases.

Persistent Escherichia coli infection in renal tubular cells enhances calcium oxalate crystal-cell adhesion by inducing ezrin translocation to apical membranes via Rho/ROCK pathway

Recent evidence has suggested that recurrent urinary tract infection (UTI) can cause not only infection stones but also metabolic stones (e.g., those containing calcium oxalate monohydrate or COM). However, precise mechanisms underlying UTI-induced metabolic stones remained unknown. In this study, Escherichia coli, the most common bacterium found in recurrent UTI was used to establish the in vitro model for persistent infection of renal epithelial cells. The promoting effects of persistent E. coli infection on kidney stone formation were validated by COM crystal-cell adhesion assay, followed by immunofluorescence study for changes in surface expression of the known COM crystal receptors. Among the five receptors examined, only ezrin had significantly increased level on the surface of persistently infected cells without change in its total level. Such translocation of ezrin to apical membranes was confirmed by Western blotting of apical membrane and cytosolic fractions and confocal microscopic examination. Additionally, persistent infection increased phosphorylation (Thr567) of ezrin. However, all of these changes induced by persistent E. coli infection were significantly inhibited by small-interfering RNA (siRNA) specific for ezrin or a Rho-associated kinase (ROCK)-specific inhibitor (Y-27632). In summary, this study provides a piece of evidence demonstrating that persistent infection by E. coli, one of the non-urease-producing bacteria, may contribute to COM metabolic stone formation by translocation of ezrin to apical membranes, thereby promoting COM crystal-cell adhesion. Such ezrin translocation was mediated via Rho/ROCK signaling pathway. These findings may, at least in part, explain the pathogenic mechanisms underlying recurrent UTI-induced metabolic kidney stone disease.

Improving the Efficacy of Antimicrobials against Biofilm-Embedded Bacteria Using Bovine Hyaluronidase Azoximer (Longidaza®)

While in a biofilm, bacteria are extremely resistant to both antimicrobials and the immune system, leading to the development of chronic infection. Here, we show that bovine hyaluronidase fused with a copolymer of 1,4-ethylenepiperazine N-oxide and (N-carboxymethyl) -1,4-ethylenepiperazinium bromide (Longidaza®) destroys both mono- and dual-species biofilms formed by various bacteria. After 4 h of treatment with 750 units of the enzyme, the residual biofilms of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae preserved about 50-70% of their initial mass. Biomasses of dual-species biofilms formed by S. aureus and the four latter species were reduced 1.5-fold after 24 h treatment, while the significant destruction of S. aureus-P. aeruginosa and S. aureus-K. pneumoniae was also observed after 4 h of treatment with Longidaza®. Furthermore, when applied in combination, Longidaza® increased the efficacy of various antimicrobials against biofilm-embedded bacteria, although with various increase-factor values depending on both the bacterial species and antimicrobials chosen. Taken together, our data indicate that Longidaza® destroys the biofilm structure, facilitating the penetration of antimicrobials through the biofilm, and in this way improving their efficacy, lowering the required dose and thus also potentially reducing the associated side effects.

Exploring Inflammatory Status in Febrile Seizures Associated with Urinary Tract Infections: A Two-Step Cluster Approach

BACKGROUND

Urinary tract infections (UTIs) are considered common facilitating factors, along with other infections, in triggering febrile seizures (FS). The main purpose of our study was to identify specific inflammatory patterns of UTI cases from other infections in a specific cluster, using a combination of inflammatory biomarkers to differentiate UTIs from other bacterial diseases triggering FS.

METHOD

This prospective study included a number of 136 patients with 197 distinct FS events, from patients hospitalized in the Pediatric Clinical Hospital Sibiu, among which 10.2% were diagnosed with UTIs.

RESULTS

In one-third of the patients with UTIs (20 cases), the symptoms were limited to fever and FS. Using two-step cluster analysis, a distinct UTI inflammatory pattern has emerged: highest platelet values (PLT), median value 331 × 103/mm3 and intermediate C-reactive protein (CRP), median value 15 mg/dL, platelet distribution width (PDW), median value 9.65%, platelet-large cell ratio (P-LCR), median value 14.45%, mean platelet volume (MPV), median value 8.60 fL and neutrophil-to-lymphocyte values (NLR), median value 3.64. Furthermore, higher PDW (median value 12.25%), P-LCR (median value 28.55%), MPV (median value 10.40 fL), CRP (median value 74.00 mg/dL) and NLR values (median value 4.11) were associated mainly (85.7%) with bacterial lower respiratory infections. UTIs were highly unlikely in these patients with significantly increased CRP values and normal values of platelet indices.

CONCLUSIONS

Considering the nonspecific clinical picture of UTIs at an early age, to optimize the management of FS, a fast diagnosis of UTI is mandatory. The analysis of the inflammatory biomarker clusters (rather than individual parameters) correlated with urine leukocyte and nitrite stick evaluation for specific age groups could help in identifying even oligosymptomatic UTIs patients. The study limitation (20 UTI cases) recommends future multicentric trials on larger datasets to validate the model.

Patients' poor performance status is an independent risk factor for urosepsis induced by kidney and ureteral stones

This study was aimed to identify the risk factors for urosepsis caused by kidney and ureteral stones. One hundred and nine patients who had kidney or ureteral stones and who were treated with trans-ureteral lithotripsy (TUL) at our institution from 2016 to 2020 were included. We investigated the risk factors for urosepsis caused by kidney or ureteral stones that occurred prior to TUL. Thirty patients (28%) had urosepsis prior to TUL. Patients were divided into a urosepsis group (n = 30, 28%) and a non-urosepsis group (n = 79, 72%). Patients' characteristics (gender, age, performance status [PS] score, presence of diabetes mellitus, and skeletal muscle mass), as well as their stone and urine characteristics (stone size, presence of obstructive ureteral stones, stone composition, and urine and stone cultures), were compared between the two groups. When compared to the non-urosepsis group, patients with urosepsis were more likely to be older (p < 0.001), female (p < 0.001), with lower skeletal muscle mass (p < 0.001) and with poor PSs (p < 0.001). For stone and urine characteristics, infection stones (p = 0.01), positive urine (p < 0.001) and stone culture (p = 0.007) were more often detected in patients with urosepsis. A multivariate analysis showed patients' poor PS to be an independent risk factor for urosepsis due to kidney and ureteral stones (OR = 15.7; 95% CI = 2.2-115, p = 0.007). Our study revealed that the most significant risk factor for urosepsis caused by kidney and ureteral stones was the patients' poor PS.

Educational review: role of the pediatric nephrologists in the work-up and management of kidney stones

BACKGROUND

The incidence of nephrolithiasis in children and adolescents is increasing and appears to double every 10 years. The most important role of the pediatric nephrologist is to diagnose and modify various metabolic and non-metabolic risk factors, as well as prevent long-term complications especially in the case of recurrent nephrolithiasis.

OBJECTIVE

The purpose of this review is to summarize the existing literature on the etiology and management of pediatric nephrolithiasis.

RESULTS

The incidence of kidney stones is increasing; dietary and environmental factors are probably the main causes for this increased incidence. In most pediatric patients, the etiology for the kidney stones can be identified. Metabolic factors, such as hypercalciuria and hypocitraturia, urinary tract infection, and urinary stasis, constitute leading causes. Herein, we review the etiologies, diagnostic work-up, and treatment options for the most prevalent causes of kidney stones. The detrimental effects of excessive dietary sodium, reduced fluid intake, and the benefits of plant-based over animal-based protein consumption on urinary crystal formation are discussed. We also review the long-term complications.

CONCLUSIONS

Pediatric nephrologists have an important role in the diagnostic work-up and prevention of recurring nephrolithiasis.

An evaluation of multidrug-resistant (MDR) bacteria in patients with urinary stone disease: data from a high-volume stone management center

PURPOSE

To investigate the prevalence of MDR bacteria in patients with urinary stones and the risk factors for its formation.

METHODS

A retrospective study was performed among patients with urinary stones in Beijing Tsinghua Changgung Hospital from December 2014 to May 2018. Patients with positive urinary cultures and drug sensitivity results were included. MDR were defined as any bacteria that have resistance to at least one agent in at least three classes of antibiotics. Bacteria distribution and resistance patterns were calculated.

RESULTS

1655 patients with urinary stones were eligible for analysis, among which 367 patients had positive urinary culture, yielding 457 isolates of 45 species. Escherichia coli remained the most common organism with a prevalence of 29.3%, followed by Enterococcus faecalis (12.0%), Proteus mirabilis (10.5%), and Klebsiella pneumonia (6.8%). 44.4% isolates were identified as MDR. The three most common Gram-negative bacteria were Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae, with a MDR rate of 84.33%, 62.5%, and 48.39%, respectively. Drug-resistant rates were different between MDR and non-MDR in ampicillin, cefazolin, ceftriaxone, cefepime, gentamicin, amikacin, and levofloxacin (all with p value < 0.05). In multivariate analysis, indwelling catheters (OR 3.1, 95% CI 1.07-8.98) and antibiotics use in the last 3 months (OR 2.14, 95% CI 1.04-4.38) were significantly associated with MDR formation.

CONCLUSIONS

MDR bacteria were common among patients with urinary stones in our center and achieved high drug-resistant rates in ampicillin, first-generation and part of third-generation cephalosporins, and fluoroquinolones. Indwelling catheters and antibiotics used in the last 3 months were independent risk factors for MDR formation. Tailored antibacterial strategies still should be established according to the local bacterial spectrum and patient condition.

Opportunities for future therapeutic interventions for hyperoxaluria: targeting oxidative stress

INTRODUCTION

Oxalate is a toxic byproduct of metabolism and is normally produced in quantities easily removed from the body. However, under specific circumstances oxalate production is increased resulting in deposition of calcium oxalate (CaOx) crystals in the kidneys as well as other organs causing inflammation and injury. Excessive buildup of crystal deposits in the kidneys causes eventual loss of renal function requiring renal transplantation. Areas covered: Cellular exposure to CaOx crystals induces the production of reactive oxygen species (ROS) with the involvement of renin-angiotensin aldosterone system (RAAS), mitochondria, and NADPH oxidase. Inflammasomes are activated and pro-inflammatory cytokines, such as IL-1β and IL-18 are produced. We reviewed results of experimental and clinical studies of crystal renal epithelial cell interactions with emphasis on cellular injury and ROS production. Expert opinion: Treatment should depend upon the level of hyperoxaluria and whether it is associated with CaOx crystal deposition. Persistent low grade or intermittent hyperoxaluria can be treated with antioxidants, free radical scavengers. Hyperoxaluria associated with CaOx crystal deposition will require administration of angiotensin II receptor blockers, and NADPH oxidase or NLRP3 inflammasome inhibitors. DASH-style diet will be beneficial in both cases.

Renal stones

Renal stone disease is a worldwide problem which carries significant morbidity. It frequently requires specialist urology intervention. Patients with recurrent disease and those at high risk require specialist investigations and review. Certain cases benefit from medical and surgical intervention. In this review, we discuss the pathophysiology, risk assessment, specialist investigations and various interventions, their rationale and evidence base. This review aims to provide an update of the previous publication in 2001 in this journal on this topic.

A Drosophila model identifies a critical role for zinc in mineralization for kidney stone disease

Ectopic calcification is a driving force for a variety of diseases, including kidney stones and atherosclerosis, but initiating factors remain largely unknown. Given its importance in seemingly divergent disease processes, identifying fundamental principal actors for ectopic calcification may have broad translational significance. Here we establish a Drosophila melanogaster model for ectopic calcification by inhibiting xanthine dehydrogenase whose deficiency leads to kidney stones in humans and dogs. Micro X-ray absorption near edge spectroscopy (μXANES) synchrotron analyses revealed high enrichment of zinc in the Drosophila equivalent of kidney stones, which was also observed in human kidney stones and Randall's plaques (early calcifications seen in human kidneys thought to be the precursor for renal stones). To further test the role of zinc in driving mineralization, we inhibited zinc transporter genes in the ZnT family and observed suppression of Drosophila stone formation. Taken together, genetic, dietary, and pharmacologic interventions to lower zinc confirm a critical role for zinc in driving the process of heterogeneous nucleation that eventually leads to stone formation. Our findings open a novel perspective on the etiology of urinary stones and related diseases, which may lead to the identification of new preventive and therapeutic approaches.

High carbonate level of apatite in kidney stones implies infection, but is it predictive?

The presence of infectious microorganisms in urinary stones is commonly inferred from stone composition, especially by the presence of struvite in a stone. The presence of highly carbonated apatite has also been proposed as a marker of the presence of bacteria within a stone. We retrospectively studied 368 patients who had undergone percutaneous nephrolithotomy (PCNL), and who also had culture results for both stone and urine. Urine culture showed no association with stone mineral content, but stone culture was more often positive in struvite-containing stones (73 % positive) and majority apatite stones (65 %) than in other stone types (54 %, lower than the others, P < 0.02). In 51 patients in whom the carbonate content of apatite could be measured, carbonate in the apatite was weakly predictive of positive stone culture with an optimal cutoff value of 13.5 % carbonate (sensitivity 0.61, specificity 0.80). In positive cultures of stones (all mineral types combined), organisms that characteristically produce urease were present in 71 % of the cases, with no difference in this proportion among different types of stone. In summary, the type of mineral in the stone was predictive of positive stone culture, but this correlation is imperfect, as over half of non-struvite, non-apatite stones were found to harbor culturable organisms. We conclude that mineral type is an inadequate predictor of whether a stone contains infectious organisms, and that stone culture is more likely to provide information useful to the management of patients undergoing PCNL.

Risk factors for septic shock after mini-percutaneous nephrolithotripsy with holmium laser

OBJECTIVE

To evaluate the risk factors for septic shock after mini-percutaneous nephrolithotripsy (MPCNL) and provide a theoretic basis for the prevention of septic shock after MPCNL.

METHODS

A total of 834 patients who underwent MPCNL from June 2004 to April 2012 were retrospectively analyzed. The χ(2) test and a logistic regression were used to identify key risk factors for septic shock after MPCNL.

RESULT

The incidence of septic shock after MPCNL was 2.40%. Logistic regression analysis identified female sex (odds ratio, 1.055E8; P <.001) and diabetes mellitus (odds ratio, 4.192; P = .001) as independent risk factors for post-MPCNL septic shock.

CONCLUSION

Female sex and diabetes mellitus are the key risk factors for septic shock after MPCNL. Routine administration of antibiotics preoperatively might reduce the incidence of septic shock.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Stability of the infection marker struvite in urinary stone samples

BACKGROUND AND PURPOSE

Struvite in kidney stones is an important marker for infection. In kidney stone samples, struvite is known to be prone to chemical breakdown, but no data exist on the stability of samples stored in dry form. The objective of this study was to examine stability of struvite under increasingly poor conditions of storage.

MATERIALS AND METHODS

Samples of struvite kidney stones were broken to obtain 38 pieces averaging 67 mg in weight, and these were randomized into four storage conditions: Airtight containers stored in the dark, open containers in the dark, open containers in ambient light, and open containers at elevated temperature (40°C). Pieces were left for 6 months, and then analyzed for changes using micro CT and Fourier transform infrared spectroscopy (FT-IR).

RESULTS

Initial samples proved to be struvite, indicating no transformation in the large specimens that had been stored in airtight containers in the dark for more than 6 years before this study. Pieces of struvite taken from these large specimens appeared unchanged by micro CT and FT-IR after being stored in closed containers for 6 months, but 8 of 9 pieces in open containers showed the presence of newberyite in surface layers, as did 10 of 10 pieces in open containers out in ambient light. All pieces stored at 40°C showed transformation of struvite, with 60% of the pieces showing the presence of amorphous phosphates, indicating complete breakdown of struvite in the surface layers of the pieces.

CONCLUSION

We conclude that struvite in dry kidney stone samples is stable when the specimens are stored in airtight containers at room temperature, even after several years.

Management of urinary tract infections associated with nephrolithiasis

Nephrolithiasis is a common clinical entity, and the incidence of renal stones appears to be increasing in the United States. Infection with uropathogens that produce urease can lead to the development of stones (infection stones), which serve as a continued source of recurrent infection and can lead to chronic kidney disease. Other than treating infection, medical management has little role in the treatment of infection stones; complete eradication of the stones with percutaneous nephrolithotomy or extracorporeal shock wave lithotripsy is required. Stones of metabolic origin can cause obstruction in the ureter and predispose to the development of urinary tract infection (UTI). Recognizing obstruction and initiating prompt drainage of the collecting system is important in the successful management of nephrolithiasis complicated by UTI. These patients are often at high risk of infection with an antimicrobial-resistant pathogen, so careful consideration of antimicrobial therapy is required, especially for patients who present with severe sepsis.

Inaccurate reporting of mineral composition by commercial stone analysis laboratories: implications for infection and metabolic stones

PURPOSE

We determined the accuracy of stone composition analysis at commercial laboratories.

MATERIALS AND METHODS

A total of 25 human renal stones with infrared spectroscopy determined composition were fragmented into aliquots and studied with micro computerized tomography to ensure fragment similarity. Representative fragments of each stone were submitted to 5 commercial stone laboratories for blinded analysis.

RESULTS

All laboratories agreed on the composition of 6 pure stones. Only 2 of 4 stones (50%) known to contain struvite were identified as struvite at all laboratories. Struvite was reported as a component by some laboratories for 4 stones previously determined not to contain struvite. Overall there was disagreement regarding struvite in 6 stones (24%). For 9 calcium oxalate stones all laboratories reported some mixture of calcium oxalate but the quantity of subtypes differed significantly among laboratories. In 6 apatite containing stones apatite was missed by the laboratories in 20% of samples. None of the laboratories identified atazanavir in a stone containing that antiviral drug. One laboratory reported protein in every sample while all others reported it in only 1. Nomenclature for apatite differed among laboratories with 1 reporting apatite as carbonate apatite and never hydroxyapatite, another never reporting carbonate apatite and always reporting hydroxyapatite, and a third reporting carbonate apatite as apatite with calcium carbonate.

CONCLUSIONS

Commercial laboratories reliably recognize pure calculi. However, variability in the reporting of mixed calculi suggests a problem with the accuracy of stone analysis results. There is also a lack of standard nomenclature used by laboratories.

Interaction of intracorporeal lithotripters with Proteus mirabilis inoculated inside artificial calcium and struvite stones

BACKGROUND AND PURPOSE

Renal calculi may contain bacteria that can remain active inside the stone and produce bacteremia and/or endotoxemia after lithotripsy. Urinary tract infection associated with urinary stones represents high morbidity. The purpose of this research was to use novel artificial struvite stones inoculated with living bacteria and to study the effect of four different intracorporeal lithotripters on bacterial inactivation after in vitro lithotripsy.

MATERIALS AND METHODS

Two types of artificial kidney stone models (calcium sulphate and mixed struvite-calcium sulphate) were manufactured and infected with Proteus mirabilis. Stones were fractured using either electrohydraulic, laser, ultrasonic, or pneumatic lithotripters. Bacterial viability was determined before and after the lithotripsy.

RESULTS

Bacterial inactivation was not affected by the stone matrix; ie, calcium or struvite. The four tested lithotripters were almost equally efficient at reducing the viability of P mirabilis in both the low and the high energy setting.

CONCLUSIONS

We were able to obtain novel artificial struvite stones infected with bacteria. Intracorporeal lithotripters are efficient at reducing the viability of P mirabilis in vitro. Tested stone materials play a minor role regarding inactivation. Whether the bactericidal effect reported is desirable or not is still to be answered, because the presence of endotoxin from cell lysis may increase the risk of urosepsis.

Biofilms in nephrology

BACKGROUND

Biofilms are bacterial communities ubiquitous to moist environments. Biofilm formation is a factor in the development and persistence of infectious diseases. In clinical nephrology, biofilms influence the development of kidney stones and affect dialysis systems, including peritoneal and central venous catheters. Biofilms also play critical roles in persistent and resistant renal and urinary tract infections.

OBJECTIVE

To describe the physiology of biofilms and potential effects of biofilms upon infectious diseases, focusing on the role of biofilms in kidney stones, indwelling catheters and dialysis equipment.

METHODS

A literature search with Medline to identify pertinent English language articles published up to early 2008 using the keywords biofilm, nephrology, renal, calculi and infection.

RESULTS/CONCLUSION

Biofilms are ubiquitous in clinical nephrology and play a role in the pathogenesis of resistant infections. Strategies for reducing the effects of biofilms in nephrology are described.

Role of bacterial biofilms in urinary tract infections

Bacterial urinary tract infections represent the most common type of nosocomial infection. In many cases, the ability of bacteria to both establish and maintain these infections is directly related to biofilm formation on indwelling devices or within the urinary tract itself. This chapter will focus on the role of biofilm formation in urinary tract infections with an emphasis on Gram-negative bacteria. The clinical implications of biofilm formation will be presented along with potential strategies for prevention. In addition, the role of specific pathogen-encoded functions in biofilm development will be discussed.

Fever after percutaneous nephrolithotomy: contributing factors

BACKGROUND AND PURPOSE

The exact mechanism of fever and urosepsis after percutaneous procedures has not been established. This research studied the frequency of fever after percutaneous nephrolithotomy (PCNL) and the contributing factors.

METHODS

In a cross-sectional study, from September 2003 to March 2004, all 217 patients with nephrolithiasis treated with PCNL at the Labbafinegad Specialized Urology Center were studied. Data were collected before, during, and after surgery.

RESULTS

The frequency of fever after PCNL was 25.8% (n=56) although in 62.2% of the cases (n=135), no prophylactic antibiotics had been administered. The mean durations of hospitalization in patients with and without fever were 5.4+/-2.3 and 3.4+/-1.7 days, respectively (p=0.001). Significant correlations were observed between fever and female sex (p=0.005), positive urine culture (p=0.02), and nephrostomy tube insertion (p=0.041). Other variables did not prove to be significant. In logistic regression analysis, female sex and nephrostomy tube insertion were independently related to post-operative fever.

CONCLUSION

Although a considerable proportion of our patients had not received prophylactic antibiotics, the rate of fever after PCNL was no higher than is reported in the literature. Use of only a short course of antibiotics before surgery for staghorn stones did not result in a higher rate of fever. Female sex created a higher risk for fever, probably because of the greater propensity to urinary tract infection. The significant relation of a nephrostomy tube to fever could be attributed to its role as a foreign body or to use in more complicated cases.

Pediatric urinary tract infections

Pediatric urinary tract infections are common. These infections have been recognized as a source of acute morbidity and long-term medical consequences in adulthood. There are various risk factors and clinical presentations in children with urinary tract infections. The main objectives in management include prompt diagnosis, appropriate antimicrobial therapy, identification of anatomic anomalies, and, in select patients, long-term follow-up.

Nephrolithiasis and increased blood pressure among females with high body mass index

BACKGROUND

We hypothesized that one reason for the heterogeneity in previously reported links between kidney stones and blood pressure (BP) was the differential effects of nephrolithiasis among subgroups of individuals. In particular, we hypothesized that the association between stone history and BP may vary with respect to sex and body size.

METHODS

Data from the Third National Health and Nutrition Examination Survey were used to estimate the association between history of stone disease and odds of prior diagnosis of hypertension and mean difference in systolic BP, diastolic BP, and pulse pressure. Nine hundred nineteen persons with a history of stones and 19,120 persons without stones were available for analysis.

RESULTS

In women, it was estimated that stone formers (SFs) experienced a 69% increase in odds of self-reported hypertension (95% confidence interval [CI], 1.33 to 2.17; P < 0.001). No significant difference was found in men. The estimated difference in mean systolic and diastolic BP comparing SFs with non-SFs increased with body mass index in both sexes, but was more pronounced in women. Mean systolic BPs in women SFs in quintiles 4 and 5 of body mass index were 7.62 mm Hg (95% CI, 1.04 to 14.2; P = 0.024) and 4.36 mm Hg (95% CI, 0.30 to 8.42; P = 0.036) greater than those in similar women non-SFs, respectively.

CONCLUSION

Our findings not only support the link between kidney stone disease and BP, but also suggest that overweight women SFs may be at significantly increased risk for hypertension.

ACP Best Practice No 181: Chemical pathology clinical investigation and management of nephrolithiasis

Renal stones have afflicted humans for millennia but there is still no solution to this problem. This review discusses the laboratory and metabolic aspects of the clinical management of patients with renal stones, both primary and secondary in origin. First, non-pharmacological interventions such as increased fluid intake, decreased protein consumption, dietary changes in sodium, calcium, oxalate, potassium, purine, vitamins, and essential fatty acids are considered. Then specific pharmacological treatment to modify urine calcium, oxalate, urate, citrate, and acidity are considered. Finally, more unusual types of stone are examined.