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

Higher Risk of Repeat Stone Surgery in Stone Formers With Concomitant Bowel Disease: Single-Center Long-Term Analysis

OBJECTIVE

To identify the need for repeat stone surgery in patients with and without bowel disease. Few studies have compared risks between different types of bowel disease and whether their need for repeat stone surgery differs.

METHODS

From our IRB-approved study, we identified patients with and without bowel disease. We categorized patients' bowel disease into 4 categories: inflammatory bowel disease (IBD), bypass procedures, bowel resection, and bowel disease not otherwise specified (eg, irritable bowel syndrome, celiac disease). Differences between patient demographics, stone disease, and recurrent stone events for patients with and without bowel disease were compared using univariate and multivariate survival analyses (SPSS 25).

RESULTS

Of all surgical stone patients (2011), 484 (24%) had some type of bowel disease. Compared to patients without bowel disease, patients with bowel disease presented with stones at an older age (62.2 ± 14.5 vs 58.4 ± 15.3 years; P <.001) and were more likely to be female (56 vs 46%; P <.001). Patients with bowel disease required more repeat stone surgery than those without bowel disease (31% vs 23%, P <.001). In multivariate analysis, patients with bypass and bowel resection were associated with more repeat surgery than patients without bowel disease (P <.001, P = .002, respectively). Patients with IBD and bowel disease not otherwise specified did not have higher risk for repeat surgery than patients without bowel disease.

CONCLUSION

Surgical stone patients with bowel disease, specifically those with prior bowel resection and bypass, had a higher risk of repeat stone surgery over time than stone formers without bowel disease.

DATA AVAILABILITY

The data sets generated and analyzed during the current study are available from the corresponding author on reasonable request.

Absolute and Relative Risks of Kidney and Urological Complications in Patients With Inflammatory Bowel Disease

INTRODUCTION

The burden of kidney and urological complications in patients with inflammatory bowel disease (IBD) remains poorly characterized.

METHODS

We analyzed association between developing IBD (as a time-varying exposure) and relative risks of receiving diagnoses of chronic kidney disease (CKD), acute kidney injury (AKI), or kidney stones, and experiencing a clinically-relevant decline in estimated glomerular filtration rate (eGFR) (CKD progression; composite of kidney failure or an eGFR decline ≥30%) in 1,682,795 individuals seeking healthcare in Stockholm, Sweden, during 2006-2018. We quantified 5- and 10-year absolute risks of these complications in a parallel matched cohort of IBD cases and random controls matched (1:5) on sex, age, and eGFR.

RESULTS

During median 9 years, 10,117 participants developed IBD. Incident IBD was associated with higher risks of kidney-related complications compared with non-IBD periods: hazard ratio (HR) (95% confidence interval) was 1.24 (1.10-1.40) for receiving a CKD diagnosis and 1.11 (1.00-1.24) for CKD progression. For absolute risks, 11.8% IBD cases had a CKD event within 10-year. Of these, 6.4% received a CKD diagnosis, and 7.9% reached CKD progression. The risks of AKI (HR 1.97 [1.70-2.29]; 10-year absolute risk 3.6%) and kidney stones (HR 1.69 [1.48-1.93]; 10-year absolute risk 5.6%) were also elevated. Risks were similar in Crohn's disease and ulcerative colitis.

DISCUSSION

More than 10% of patients with IBD developed CKD within 10-year from diagnosis, with many not being identified through diagnostic codes. This, together with their elevated AKI and kidney stone risks, highlights the need of established protocols for kidney function monitoring and referral to nephrological/urological care for patients with IBD.

Association between inflammatory bowel disease, nephrolithiasis, tubulointerstitial nephritis, and chronic kidney disease: A propensity score-matched analysis of US nationwide inpatient sample 2016-2018

OBJECTIVES

The incidence and prevalence of inflammatory bowel disease (IBD), mainly including ulcerative colitis (UC) and Crohn's disease (CD), are increasing globally. We aimed to evaluate the potential association between IBD and nephrolithiasis, tubulointerstitial nephritis, and chronic kidney disease (CKD).

METHODS

Data of hospitalized adults ≥20 years of age were extracted from the U.S. National Inpatient Sample (NIS) during 2016-2018. Patients with UC, CD, or CKD were identified through the International Classification of Diseases, Tenth Revision (ICD-10) codes. Propensity score matching (PSM) analysis (1:1) was conducted to balance the characteristics between groups. Logistic regression analyses were performed to determine the relationships between UC or CD and kidney conditions.

RESULTS

Three cohorts were included for analysis after PSM analysis. Cohorts 1, 2 and 3 contained 235 262 subjects (117 631 with CD or without IBD), 140 856 subjects (70 428 with UC or without IBD), and 139 098 subjects (69 549 with CD or UC), respectively. Multivariate analysis revealed that compared to non-IBD individuals, CD patients were significantly associated with greater odds for nephrolithiasis (adjusted odds ratio [aOR] 2.25, 95% confidence interval [CI] 2.08-2.43), tubulointerstitial nephritis (aOR 1.31, 95% CI 1.24-1.38), CKD at any stage (aOR 1.28, 95% CI 1.24-1.32), and moderate-to-severe CKD (aOR 1.22, 95% CI 1.17-1.26), while UC was associated with a higher rate of nephrolithiasis. Compared to UC, CD was associated with higher odds for all such kidney conditions.

CONCLUSIONS

Patients with CD are more likely to have nephrolithiasis, tubulointerstitial nephritis, CKD at any stage, and moderate-to-severe CKD compared to non-IBD individuals.

Causal effects of inflammatory bowel diseases on the risk of kidney stone disease: a two-sample bidirectional mendelian randomization

BACKGROUND

Existing epidemiological observational studies have suggested interesting but inconsistent clinical correlations between inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), and kidney stone disease (KSD). Herein, we implemented a two-sample bidirectional Mendelian randomization (MR) to investigate the causal relationship between IBD and KSD.

METHODS

Data on IBD and KSD were obtained from Genome-Wide Association Studies (GWAS) summary statistics and the FinnGen consortium, respectively. Strict selection steps were used to screen for eligible instrumental SNPs. We applied inverse variance weighting (IVW) with the fix-effects model as the major method. Several sensitivity analyses were used to evaluate pleiotropy and heterogeneity. Causal relationships between IBD and KSD were explored in two opposite directions. Furthermore, we carried out multivariable MR (MVMR) to obtain the direct causal effects of IBD on KSD.

RESULTS

Our results demonstrated that CD could increase the risk of KSD (IVW: OR = 1.06, 95% CI = 1.03-1.10, p < 0.001). Similar results were found in the validation group (IVW: OR = 1.05, 95% CI = 1.01-1.08, p = 0.013) and in the MVMR analysis. Meanwhile, no evidence of a causal association between UC and KSD was identified. The reverse MR analysis detected no causal association.

CONCLUSIONS

This MR study verified that CD plays a critical role in developing kidney stones and that the effect of UC on KSD needs to be further explored.

Urolithiasis in patients with inflammatory bowel disease: A systematic review and meta-analysis of 13,339,065 individuals

BACKGROUND

This study aimed to summarize the current literature regarding the prevalence of renal stones in patients with inflammatory bowel disease (IBD). Moreover, we aimed to evaluate the risk factors of urolithiasis in patients with IBD and the difference between patients with IBD and healthy controls in terms of urinary profile.

METHODS

On February 23, 2022, a computerized search was conducted on PubMed, OVID via MEDLINE, Web of Science, and Scopus using relevant keywords. Three independent reviewers performed 2-stage screening and data extraction. The National Institutes of Health tools were employed for quality assessment. Review Manager 5.4 software was used to calculate the mean difference (MD) between IBD patients and non-IBD in terms of urine profile using the Inverse-variance model and to estimate the odds ratio of reported risk factors for renal stones with the Generic Inverse-Variance model.

RESULTS

Thirty-two articles (n = 13,339,065 patients) were included. The overall prevalence of renal stones in patients with IBD was 6.3%, 95% Confidence interval (4.8%-8.3%). The prevalence of urolithiasis was more common in Chron's disease vs Ulcerative colitis (7.9% vs 5.6%) and in old studies (1964-2009) than in more recent studies (2010-2022) (7.3% vs 5.2%), respectively. Compared to non-IBD patients, patients with IBD were associated with significantly lower urine volume (MD = -518.84 mL/day, P < .00001), calcium 24-hour urine (MD = -28.46 mg/day, P < .0001), citrate 24-hour urine (MD = -144.35 mg/day, P < .00001), sodium 24-hour urine (MD = -23.72 mg/day, P = .04), and magnesium 24-hour urine (MD = -33.25 mg/day, P < .00001).

CONCLUSION

The overall prevalence of renal stones in patients with IBD was comparable to the general population. Patients with Chron's disease were associated with a higher prevalence of urolithiasis compared to Ulcerative colitis. Drugs that induce renal calculi should be stopped in high-risk patients.

The effectiveness of citrates and pyridoxine in the treatment of kidney stones

The prevalence of nephrolithiasis is increasing across all demographic groups. Apart from the morbidity associated with an acute occurrence, preventative treatment is essential for stone disease, which can become a long-term problem. Simple interventions like fluid intake optimization and dietary modification are effective for most stone types. However, patients with specific metabolic abnormalities may require pharmaceutical therapy if lifestyle changes are insufficient to reduce the risk of stone recurrence. The treatment of citrates and/or pyridoxines may help eliminate or prevent recurrences of kidney stones, especially when they are composed of uric acid, calcium oxalate, calcium phosphate, or the latter two together. In cases of struvite stones, which often necessitate a surgical approach, acetohydroxamic acid emerges as a valuable second-line treatment option. Thiol-binding agents may be needed for cystinuria, as well as lifestyle modifications. Successful treatment reduces stone recurrence and the need to remove stones surgically.

Inflammatory bowel disease increases the levels of albuminuria and the risk of urolithiasis: a two-sample Mendelian randomization study

BACKGROUND

Alterations in kidney function and increased risk of kidney diseases in patients with inflammatory bowel disease (IBD) have been reported, but the causal relationship remains unclear. Herein, Mendelian randomization was employed to identify the causal effect of inflammatory bowel disease on kidney function and the risk of chronic kidney disease (CKD), urolithiasis, and IgA nephropathy.

METHODS

The International Inflammatory Bowel Disease Genetics Consortium provided the summary-level genome-wide association study (GWAS) data that correlates with Crohn's disease (CD) and ulcerative colitis (UC). GWAS data for estimated glomerular filtration rate from serum creatinine (eGFRcrea), urine albumin-creatinine ratio (uACR), and CKD were obtained from the CKDGen Consortium, and GWAS data for urolithiasis were obtained from the FinnGen consortium. The summary-level GWAS data for IgA nephropathy were obtained from the meta-analysis of UK-biobank, FinnGen, and Biobank Japan. Inverse-variance weighted was used as the primary estimate. Furthermore, the Steiger test was used to validate the direction of causality.

RESULTS

The inverse-variance weighted data revealed that genetically predicted UC significantly increased uACR levels, while genetically predicted CD significantly increased the risk of urolithiasis.

CONCLUSIONS

UC increases the levels of uACR, and CD increases the risk of urolithiasis.

Short bowel syndrome: Complications and management

Short bowel syndrome (SBS) occurs when a patient loses bowel length or function significantly enough to cause malabsorption, oftentimes requiring lifelong parenteral support. In adults, this occurs most commonly in the setting of massive intestinal resection, whereas congenital anomalies and necrotizing enterocolitis predominate in children. Many patients with SBS develop long-term clinical complications over time related to their altered intestinal anatomy and physiology or to various treatment interventions such as parenteral nutrition and the central venous catheter through which it is administered. Identifying, preventing, and treating these complications can be challenging. This review will focus on the diagnosis, treatment, and prevention of several complications that can occur in this patient population, including diarrhea, fluid and electrolyte imbalance, vitamin and trace element derangements, metabolic bone disease, biliary disorders, small intestinal bacterial overgrowth, d-lactic acidosis, and complications of central venous catheters.

Time Course and Risk Factors for Repeat Procedures After Ureteroscopy or Shockwave Lithotripsy

OBJECTIVE

To determine risk factors and time course for repeat procedures after ureteroscopy (URS) or shockwave lithotripsy (SWL) procedure using a large employer-based claims database.

METHODS

We identified all patients who underwent treatment for ureteral or renal stone with URS or SWL from January 1, 2007 to December 31, 2014 using the IBM MarketScan Commercial Database. Repeat stone procedure was evaluated after a 90-day grace period from the index procedure. Patients were followed until December 31, 2017. We performed multivariate analyses using Cox proportional hazards to determine independent risk factors for repeat procedure after the initial stone removal.

RESULTS

A total of 189,739 patients underwent a SWL or URS and were included in the study. The incidence of repeat procedure per 100 person years was 6.8, and 4.4 after SWL and URS, respectively. The median time to reoperation was 12.5 months for SWL and 14.6 months for URS. On multivariable analysis, SWL was associated with an increased risk of repeat procedure compared to URS. (HR = 1.63). Paralysis, neurogenic bladder and inflammatory bowel disease were also associated with an increased risk of repeat procedure (HR = 1.66, 1.40, and 1.36 respectively) CONCLUSION: In a large national cohort, patients with paralysis and neurogenic bladder had a significantly higher risk of repeat stone procedure. SWL was associated with higher risk of repeat procedure than URS. Urologists can use these data to identify and counsel patients at high risk for need for recurrent procedure.

Short- and long-term complications after living donor ileal resection

Intestinal transplantation from deceased donors is the established procedure for patients with irreversible intestinal failure. However, a living-donor intestinal transplant has not been routinely performed yet because of undefined surgical risks to the donor. In this report, we reviewed our experience with living-donor ileal resection from May 1999 to December 2021. A total of 40 living-donor ileal resections were performed for 40 intestinal transplant recipients. Clinical data were prospectively collected and analyzed for postoperative complications after ileal procurement. None of the donors experienced life-threatening complications or mortality. Six (15%) of 40 donors experienced minor operative complications. Transit intestinal graft inadequacy including weight loss, diarrhea, and vitamin B12 deficiency was common early following surgery, but was manageable and disappeared in most cases within a year. All donors had significant reductions in total plasma cholesterol and low-density lipoprotein cholesterol concentrations after donation as compared with the baseline levels. With an average follow-up of 67.8 months, bilateral kidney stones occurred in one donor and gallstones in the other. All the donors have regained their normal capacity for work. Living-donor ileal resection is associated with minimal short- and long-term morbidity and remains an attractive alternative for potential recipients when suitable deceased donors are unavailable.

Renal and Urological Disorders Associated With Inflammatory Bowel Disease

Renal and urinary tract complications related to inflammatory bowel disease (IBD) have been relatively understudied in the literature compared with other extraintestinal manifestations. Presentation of these renal manifestations can be subtle, and their detection is complicated by a lack of clarity regarding the optimal screening and routine monitoring of renal function in IBD patients. Urolithiasis is the most common manifestation. Penetrating Crohn's disease involving the genitourinary system as an extraintestinal complication is rare but associated with considerable morbidity. Some biologic agents used to treat IBD have been implicated in progressive renal impairment, although differentiating between drug-related side effects and deteriorating kidney function due to extraintestinal manifestations can be challenging. The most common findings on renal biopsy of IBD patients with renal injury are tubulointerstitial nephritis and IgA nephropathy, the former also being associated with drug-induced nephrotoxicity related to IBD medication. Amyloidosis, albeit rare, must be diagnosed early to reduce the chance of progression to renal failure. In this review, we evaluate the key literature relating to renal and urological involvement in IBD and emphasize the high index of suspicion required for the prompt diagnosis and treatment of these manifestations and complications, considering the potential severity and implications of acute or chronic loss of renal function. We also provide suggestions for future research priorities.

Risk of Urolithiasis in Patients With Inflammatory Bowel Disease: A Nationwide Danish Cohort Study 1977-2018

BACKGROUND AND AIMS

Patients with inflammatory bowel disease (IBD) are suggested to be at increased risk of urolithiasis, but the magnitude of risk and the impact of medical and surgical treatment on this risk remain unknown. We therefore aimed to determine overall and treatment-related risk of urolithiasis in patients with IBD in a nationwide population-based cohort study.

METHODS

Using national registers, we identified all patients with IBD and all cases of urolithiasis in Denmark during 1977-2018. We obtained information on all IBD medications and surgical procedures during 1995-2018. IBD cases were matched 1:10 on age and sex to non-IBD individuals.

RESULTS

In total, 2,549 (3%) of 75,236 IBD patients and 11,258 (2%) of 767,403 non-IBD individuals developed urolithiasis, resulting in a 2-fold increased risk of urolithiasis (HR, 2.27; 95% CI, 2.17-2.38) in patients with IBD. The patients were also at increased risk of repetitive urolithiasis events (RR, 1.09; 95% CI: 1.04-1.15) and had increased risk of urolithiasis prior to IBD diagnosis (OR, 1.42; 95% CI: 1.34-1.50). After IBD diagnosis, risk of urolithiasis was associated with anti-TNF therapy and surgery.

CONCLUSION

Patients with IBD had a 2-fold increased risk of urolithiasis after IBD diagnosis and a 42% increased risk prior to IBD diagnosis. Risk was increased in anti-TNF exposed patients, and after surgery, suggesting that IBD severity per se and surgery, with altered intestinal absorption, increase risk of urolithiasis. Since stone formation is associated with adverse outcomes including sepsis, subpopulations of IBD patients, especially those undergoing strong immunosuppression might benefit from additional urolithiasis screening.

Prevalence of Renal Stones Among Patients With Inflammatory Bowel Disease in Saudi Arabia

INTRODUCTION

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory bowel diseases (IBD) that affect the gastrointestinal tract with no identified etiology. IBD has been associated with several extraintestinal manifestations (EIMs), including renal involvement such as renal stones (nephrolithiasis), resulting in significant morbidity. This study aims to estimate the prevalence of renal stones among IBD patients in Saudi Arabia.

METHODS

This is a retrospective study conducted at King Abdulaziz University Hospital between January 2019 and December 2020. All IBD patients with abdominal imaging studies were included in the study regardless of their age. Data were collected from the electronic hospital information system and analyzed.

RESULTS

A total of 363 IBD patients fulfilled the study inclusion criteria. Nephrolithiasis was detected radiologically in 3.6% of the cohort (5.1% of UC and 2.7% of CD patients). Patients with renal stones are older (P=0.002) and more likely to be diabetic (P=0.047), have microscopic hematuria (P<0.001), and proteinuria (P=0.002). Binary logistic regression analysis showed that older age at diagnosis (P=0.003) and microscopic hematuria (P=0.02) are independent predictors for renal stones.

CONCLUSION

 The study reported that 3.6% of Saudi IBD patients had renal stones, with a higher prevalence of renal stones formation among UC patients than Crohn's. Older age at diagnosis and the presence of microscopic hematuria may predict the development of renal stones. Future studies should be conducted in a prospective manner at multiple centers across Saudi Arabia for further investigation.

Nutrition and Kidney Stone Disease

The prevalence of kidney stone disease is increasing worldwide. The recurrence rate of urinary stones is estimated to be up to 50%. Nephrolithiasis is associated with increased risk of chronic and end stage kidney disease. Diet composition is considered to play a crucial role in urinary stone formation. There is strong evidence that an inadequate fluid intake is the major dietary risk factor for urolithiasis. While the benefit of high fluid intake has been confirmed, the effect of different beverages, such as tap water, mineral water, fruit juices, soft drinks, tea and coffee, are debated. Other nutritional factors, including dietary protein, carbohydrates, oxalate, calcium and sodium chloride can also modulate the urinary risk profile and contribute to the risk of kidney stone formation. The assessment of nutritional risk factors is an essential component in the specific dietary therapy of kidney stone patients. An appropriate dietary intervention can contribute to the effective prevention of recurrent stones and reduce the burden of invasive surgical procedures for the treatment of urinary stone disease. This narrative review has intended to provide a comprehensive and updated overview on the role of nutrition and diet in kidney stone disease.

Association of Kidney Stone Disease (KSD) with Primary Gastrointestinal Surgery: a Systematic Review over Last 2 Decades

PURPOSE OF REVIEW

We aim to provide an up-to-date literature review to further characterise the association of kidney stone disease (KSD) with gastrointestinal (GI) surgery. As KSD is associated with significant morbidity, it is important to quantify and qualify this association to provide better care and management for the patient subgroup.

OBJECTIVE

To perform a systematic review of the existing literature to evaluate the association of KSD following GI surgery.

METHODS

A literature search was performed of the following databases: MEDLINE, EMBASE, Scopus, Google Scholar, Key Urology, Uptodate and Cochrane Trials from January 2000 to June 2020.

RECENT FINDINGS

A total of 106 articles were identified, and after screening for titles, abstracts and full articles, 12 full papers were included. This involved a total of 9299 patients who underwent primary GI surgery. Over a mean follow-up period of 5.4 years (range: 1-14.4 years), 819 (8.8%) developed KSD, varying from 1.2 to 83% across studies. The mean time to stone formation was approximately 3 years (range: 0.5-9 years). In the 4 studies that reported on the management of KSD (n = 427), 38.6% went on to have urological intervention. There is a high incidence of KSD following primary GI surgery, and after a mean follow-up of 3 years, around 9% of patients developed KSD. While the GI surgery was done for obesity, inflammatory bowel disease or cancer, the risk of KSD should be kept in mind during follow-up, and prompt urology involvement with metabolic assessment, medical and or surgical management offered as applicable.

Small intestine resection increases oxalate and citrate transporter expression and calcium oxalate crystal formation in rat hyperoxaluric kidneys

Short bowel (SB) increases the risk of kidney stones. However, the underlying mechanism is unclear. Here, we examined how SB affected renal oxalate and citrate handlings for in vivo hyperoxaluric rats and in vitro tubular cells. SB was induced by small intestine resection in male Wistar rats. Sham-operated controls had no resection. After 7 days of recovery, the rats were divided into control, SB (both fed with distilled water), ethylene glycol (EG), and SB+EG (both fed with 0.75% EG for hyperoxaluric induction) groups for 28 days. We collected the plasma, 24 h of urine, kidney, and intestine tissues for analysis. Hypocitraturia was found and persisted up to 28 days for the SB group. Hypocalcemia and high plasma parathyroid hormone (PTH) levels were found in the 28-day SB rats. SB aggravated EG-mediated oxalate nephropathy by fostering hyperoxaluria and hypocitraturia, and increasing the degree of supersaturation and calcium oxalate (CaOx) crystal deposition. These effects were associated with renal up-regulations of the oxalate transporter solute carrier family 26 (Slc26)a6 and citrate transporter sodium-dependent dicarboxylate cotransporter-1 (NaDC-1) but not Slc26a2. The effects of PTH on the SB kidneys were then examined in NRK-52E tubular cells. Recombinant PTH attenuated oxalate-mediated cell injury and up-regulated NaDC-1 via protein kinase A (PKA) activation. PTH, however, showed no additive effects on oxalate-induced Slc26a6 and NaDC-1 up-regulation. Together, these results demonstrated that renal NaDC-1 upregulation-induced hypocitraturia weakened the defense against Slc26a6-mediated hyperoxaluria in SB kidneys for excess CaOx crystal formation. Increased tubular NaDC-1 expression caused by SB relied on PTH.

Trends in the prevalence of kidney stones in the United States from 2007 to 2016

The overall prevalence of kidney stones (KS) in the US rose from 3.2% in 1980 to 10.1% in 2016, but the trends in important subgroups have not been reported. We examined the prevalence trends of KS in subgroups of age, sex and race in the US and identified relevant laboratory factors associated with a history of KS using National Health and Nutrition Examination Survey (NHANES) data. We conducted a cross-sectional study among 28,209 US adults aged ≥ 20 years old in the NHANES from 2007 to 2016. We calculated the prevalence of a self-reported history of KS by using weights and standardized to the 2010 US Census population. We also compared relevant laboratory values according to the history of KS. The prevalence of KS decreased from 8.7% in 2007-2008 to 7.2% in 2011-2012 but then increased to 9.0% in 2013-2014 and 10.1% in 2015-2016. However, the overall prevalence of KS increased over 2007-2016 (p-trend = 0.02). Prevalence of KS among men was higher than women. Among men aged 20-79, there were significant quadratic trends in the prevalence of KS. Whereas, the prevalence of KS increased as a linear trend among women aged 20-59 years over 2007-2016. There were no consistent trends in the prevalence of KS by race. The prevalence trend of KS among non-Hispanic whites was 9.8% from 2007 to 2010 then dropped to 7.9% in 2011-2012 and increased to 10.6% in 2013-2014 and 12.1% in 2015-2016. A similar trend was also observed among non-Hispanic blacks. Among Hispanic, the prevalence of KS was 7.6% in 2007-2008 and 7.4% in 2009-2010 and then fluctuated over the next several time periods. For non-Hispanic Asians, the range was 4.4-4.6%. Regarding relevant laboratory factors, after adjusting for sex, race, age, BMI, smoking status, alcohol drinking, history of diabetes and gout, urine albumin-creatinine ratio and serum osmolality were independently associated with the history of KS in women and men. In conclusion, there was substantial variability in KS prevalence across individual 2-year time periods. This variation of period-specific prevalence values emphasizes the importance of looking at long-term trends and using more than a single 2-year cycle in analyses to increase the precision of the estimate. However, there was an overall increase in the prevalence of KS over 2007-2016.

Renal involvement in paediatric inflammatory bowel disease

Inflammatory bowel disease (IBD), which includes Crohn's disease, ulcerative colitis and inflammatory bowel disease unclassified, is a chronic inflammatory disorder that predominantly affects the gastrointestinal (GI) tract and has a rising incidence in both children and adults. Symptoms are caused by inappropriate inflammatory response triggered by interaction between the environment, gut microbiome and host immune system in a genetically susceptible individual. Extranintestinal manifestations of IBD are common and can affect any body system outside the gut; they can precede or run parallel to GI inflammation. Renal involvement in IBD is uncommon and can be part of extraintestinal manifestation or metabolic complications of IBD. Many medications used to treat IBD can cause renal damage. Renal manifestation in children with IBD can range from asymptomatic biochemical abnormalities to variable stages of renal impairment with significant morbidity and even mortality burden.

[Stone therapy-use and limitations of the guidelines]

Increase of medical knowledge, technical innovation together with a demographic change, and increase of stone incidence in daily practice challenges guideline preparation and clinical studies. Increasing interdisciplinary collaboration in stone treatment can also be demonstrated in the number of affiliated professional and working groups in the current guideline update. The following case illustrates treatment options in a symptomatic patient harbouring bilateral stones and metabolic risk factors. Decision guidance for treatment and recurrence prevention measures are presented on the basis of expert opinion and available published evidence.

Urolithiasis in complicated inflammatory bowel disease: a comprehensive analysis of urine profile and stone composition

PURPOSE

To evaluate the impact of extensive surgery on urine profile, serum exams and stone composition of complicated IBD patients.

METHODS

Patients with IBD and a history of total proctocolectomy (TPC) with fecal diversion (end ileostomy or ileal pouch anal anastomosis-IPAA) were selected. Only patients with at least one complete 24-h urine profile were included. A case-control study was performed selecting patients with kidney stone disease in a random way who had also at least on complete 24-h urine profile. Case and controls were matched for age, gender, and body mass index (BMI). Groups were compared to urine profile, serum exams and stone composition.

RESULTS

Sixty-eight patients were enrolled in this study, 34 patients with IBD who underwent TPC and had diagnosis of kidney stones and 34 matched patients with only kidney stones. IBD patients had a significantly lower urine volume, urine citrate and urine sodium. Regarding serum exams, only serum bicarbonate was statistically significant lower. In both groups, calcium oxalate stone was the most common.

CONCLUSION

Patients with IBD with TPC and kidney stones have a low urine volume and low urine citrate as main risk factors for kidney stone formation. As seen in the general population, calcium oxalate is the most common stone composition.

Inflammatory Bowel Diseases Are Associated With an Increased Risk for Chronic Kidney Disease, Which Decreases With Age

BACKGROUND & AIMS

It is not clear what factors affect risk of chronic kidney disease (CKD) in patients with inflammatory bowel disease (IBD); increased risk has been inconsistently associated with use of 5-aminosalicylates (5-ASAs). We aimed to calculate the relative hazard of CKD among patients with IBD, adjusted for CKD risk factors, and to determine whether IBD medications are associated with change in estimated glomerular filtration rate (eGFR).

METHODS

We performed a retrospective cohort study of data from The Health Improvement Network. Patients with IBD (n = 17,807) were matched for age, sex, and practice to individuals without IBD (n = 63,466). The relative hazard of CKD, stages 3 through 5D, in patients with IBD was calculated using a Cox proportional hazards model adjusted for common CKD risk factors. We also evaluated the association of 5-ASAs, azathioprine, and methotrexate with change in eGFR using a longitudinal model.

RESULTS

After we controlled for risk factors associated with CKD, we found IBD to be associated with development of CKD in patients 16-77 years old. As patient age increased, the adjusted hazard ratio for CKD decreased monotonically, from 7.88 (95% CI, 2.56-24.19) at age 16 to 1.13 (95% CI, 1.01-1.25) at age 77. In the longitudinal analysis, exposure to 5-ASAs or methotrexate was not associated with change in eGFR, whereas azathioprine was associated with a slightly higher eGFR (0.32 mL/min/1.73 m²; 95% CI, 0.16-0.48).

CONCLUSIONS

In a retrospective study of more than 80,000 persons, we found that IBD is associated with increased risk of CKD, and the hazard ratio is highest among younger patients. Commonly used non-biologic therapeutic agents were not associated with lower eGFR.

[Renal and Urinary Manifestations of Inflammatory Bowel Disease]

The incidence of inflammatory bowel disease (IBD) is increasing rapidly and extra-intestinal manifestations in IBD are also increasing. The prevalence of renal and urinary involvement in IBD ranges from 4-23%. Nephrolithiasis is the most common urinary complication in IBD patients. Parenchymal renal disease is rare but has been well documented and presents most commonly as glomerulonephritis or tubulointerstitial nephritis. The overall morbidity of IBD-related renal manifestations is significant. Therefore, a high index of clinical suspicion and optimal monitoring of the renal function are needed for the early diagnosis and prevention of IBD-related renal manifestations and complications.

Extraintestinal Manifestations of Inflammatory Bowel Disease: Epidemiology, Etiopathogenesis, and Management

PURPOSE OF REVIEW

Extraintestinal manifestations (EIMs) of inflammatory bowel disease (IBD) represent a complex array of disease processes with variable epidemiologic penetrance, genetic antecedents, and phenotypic presentations. The purpose of this review is to provide an overview of primary and secondary EIMs as well as salient treatment strategies utilized.

RECENT FINDINGS

While the genetic antecedents remain incompletely understood, the treatment armamentarium for EIMs has expanded with new pharmaceutical drug classes that effectively treat IBD. EIMs are an increasingly recognized complication of IBD that require prompt recognition, multidisciplinary management, and a multifaceted therapeutic approach. This review highlights the complexities and ramifications of EIM management and offers therapeutic guidance.

Altered uric acid metabolism in isolated colonic Crohn's disease but not ulcerative colitis

BACKGROUND AND AIM

Patients with inflammatory bowel disease (IBD) have higher incidence of developing nephrolithiasis. Increased uric acid production induced by Saccharomyces cerevisiae exacerbates colitis in mice. We aimed to evaluate the association between serum uric acid level and disease activity in IBD population.

METHODS

Four hundred and thirty-five patients enrolled in Jinling Hospital from January 1, 2015 to August 31, 2017 were included in the retrospective study. Clinical parameters were collected and compared with non-IBD matched controls (n = 51). Serum uric acid to creatinine ratio (UA/Cr) was used as a biomarker for uric acid metabolism. Sixty-five active IBD patients were longitudinally studied to investigate the UA/Cr before and after therapy. Linear mixed models were estimated for Crohn's disease (CD) group to explore the relationship between UA/Cr and other parameters.

RESULTS

Uric acid to creatinine ratio was significantly correlated with Crohn's disease activity index (ρ = 0.184, P = 0.002) and Harvey Bradshaw index (ρ = 0.154, P = 0.010) and C-reactive protein (ρ = 0.591, P < 0.001) in CD group. Colonic CD and anti-Saccharomyces cerevisiae antibody (ASCA) positive CD had an increased UA/Cr compared with L1, L3, and ASCA negative CD (P = 0.027, P = 0.0013, and P = 0.043, respectively). A significant decrease in UA/Cr was observed after induction therapy in active CD (P = 0.0002) but not in ulcerative colitis (P = 0.076).

CONCLUSION

Uric acid to creatinine ratio correlated with disease activity in CD. Colonic CD and ASCA positive CD had an increased UA/Cr. Effective treatment for CD patients lowered UA/Cr. Uric acid metabolism might be a novel aspect to investigate disease activity of IBD.

Prevalence of kidney stones in the USA: The National Health and Nutrition Evaluation Survey

Objective:

The National Health and Nutrition Examination Survey (NHANES) has demonstrated an upward trend in prevalence of kidney stones (KSs) in the past 30 years. We aim to report the current prevalence of KSs.

Methods:

Research was based upon a cross-sectional analysis of response to the 2007–2014 NHANES. The prevalence of self-reported KS history was calculated using weights and design factors reported by NHANES. Four cycles of NHANES data were analyzed separately (2007–2014), and KS-prevalence trends in adult individuals for different age groups were compared. Analysis was performed using SAS ver.9.4.

Results:

The prevalence of KSs was 10.1% for the last 2013–2014 NHANES cycle. The highest prevalence of KSs was observed in males older than 60 years, at 17.8%, followed by males 40–59 years old at 12.6%. This trend changes in the 20–39-year-old age group, wherein females had a higher prevalence than males—7.5% for females compared to 4.5% in males. Females in the study showed a steady increase in KSs prevalence through the study cycles: 6.6% in 2007 to 9.5% in 2013 ( p < 0.05). The increase in females ages 20 to 39, almost doubled in prevalence: 3.9 to 7.5%, from 2007 to 2013 ( p < 0.05). Females older than 60 years of age have remained stable, with prevalence of 8.9% in 2007 to 9.8% in 2013. Males showed a slight decrease in prevalence from 2007 to 2014, from 12.7% in 2007 to 11.4% in 2014. Prevalence in males and females older than 60 years old were relatively stable.

Conclusions:

Prevalence of KSs has remained stable in males and has increased in females. Females of child-bearing age showed the most significant increase. For this specific group, there has been a steady increase in the last seven years.

Level of evidence:

IV

Renal Manifestations of Inflammatory Bowel Disease

Renal and urinary involvement has been reported to occur in 4% to 23% of inflammatory bowel disease (IBD) patients. Parenchymal renal disease is rare and most commonly affects glomerular and tubulointerstitial compartments. The most common findings on renal biopsy of IBD patients are IgA nephropathy and tubulointerstitial nephritis. Overall morbidity of IBD-related renal manifestations is significant, and there is often only a short window of injury reversibility. This, along with subtle clinical presentation, requires a high index of suspicion and routine monitoring of renal function. There are no established guidelines for the optimal screening and monitoring of renal function in IBD patients.

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.

Risk factors for gallstones and kidney stones in a cohort of patients with inflammatory bowel diseases

Background

Gallstones and kidney stones are known complications of inflammatory bowel diseases (IBD). Risk factors have been insufficiently studied and explanatory studies date back up to 30 years. It remains unclear, whether improved treatment options also influenced risk factors for these complications.

Objectives

Identifying risk factors for gallstones and kidney stones in IBD patients.

Methods

Using data from the Swiss Inflammatory Bowel Disease Cohort Study we assessed associations of diseases characteristics with gallstones and kidney stones in univariate and multivariate logistic regression analyses.

Results

Out of 2323 IBD patients, 104 (7.8%) Crohn’s disease (CD) and 38 (3.8%) ulcerative colitis (UC) patients were diagnosed with gallstones. Significant risk factors for gallstones were diagnosis of CD, age at diagnosis, disease activity and duration, NSAID intake, extra-intestinal manifestations and intestinal surgery. Kidney stones were described in 61 (4.6%) CD and 30 (3.0%) UC patients. Male gender, disease activity, intestinal surgery, NSAID usage and reduced physical activity were significant risk factors. Hospitalization was associated with gallstones and kidney stones. The presence of gallstones increased the risk for kidney stones (OR 4.87, p<0.001).

Conclusion

The diagnosis of CD, intestinal surgery, prolonged NSAID use, disease activity and duration and bowel stenosis were significantly associated with cholecystonephrolithiasis in IBD.

Nephrolithiasis as a common urinary system manifestation of inflammatory bowel diseases; a clinical review and meta-analysis

CONTEXT

The extra-intestinal manifestations of inflammatory bowel disease (IBD) are common and involve other organs or systems for example; urinary system.

EVIDENCE ACQUISITIONS

For this review, we used a variety of sources by searching through Web of Science, PubMed, EMBASE, Scopus and directory of open access journals (DOAJ).

RESULTS

Urinary complications may occur in up to 22% of patients and nephrolithiasis or renal/kidney stones have been suggested to be a common manifestation of disease in forms of uric acid, calcium phosphate or calcium oxalate. We performed a meta-analysis on five clinical trials and reported that correlation between IBD and formation of stone in renal system is positive and significant (Fix-effect model; CI: 95%, P <0.001, and randomeffect model; CI: 95%, P = 0.03).

CONCLUSIONS

Based on the reports of the clinical trials, calcium oxalate is more prevalent in Crohn's disease (CD) than in ulcerative colitis (UC).

Enteric hyperoxaluria in chronic pancreatitis

Chronic pancreatitis may lead to steatorrhea, enteric hyperoxaluria, and kidney damage. However, the prevalence and determinants of hyperoxaluria in chronic pancreatitis patients as well as its association with renal function decline have not been investigated.We performed an observational study. Urine oxalate to creatinine ratio was assessed on 2 independent random urine samples in consecutive adult patients with chronic pancreatitis followed at the outpatient clinic from March 1 to October 31, 2012. Baseline characteristics and annual estimated glomerular filtration rate (eGFR) change during follow-up were compared between patients with hyper- and normo-oxaluria.A total of 48 patients with chronic pancreatitis were included. The etiology of the disease was toxic (52%), idiopathic (27%), obstructive (11%), autoimmune (6%), or genetic (4%). Hyperoxaluria (defined as urine oxalate to creatinine ratio >32 mg/g) was found in 23% of patients. Multivariate regression analysis identified clinical steatorrhea, high fecal acid steatocrit, and pancreatic atrophy as independent predictors of hyperoxaluria. Taken together, a combination of clinical steatorrhea, steatocrit level >31%, and pancreatic atrophy was associated with a positive predictive value of 100% for hyperoxaluria. On the contrary, none of the patients with a fecal elastase-1 level >100 μg/g had hyperoxaluria. Longitudinal evolution of eGFR was available in 71% of the patients, with a mean follow-up of 904 days. After adjustment for established determinants of renal function decline (gender, diabetes, bicarbonate level, baseline eGFR, and proteinuria), a urine oxalate to creatinine ratio >32 mg/g was associated with a higher risk of eGFR decline.Hyperoxaluria is highly prevalent in patients with chronic pancreatitis and associated with faster decline in renal function. A high urine oxalate to creatinine ratio in patients with chronic pancreatitis is best predicted by clinical steatorrhea, a high acid steatocrit, and pancreatic atrophy. Further studies will need to investigate the mechanisms of renal damage in chronic pancreatitis and the potential benefits of therapies reducing oxaluria.

Prevalence of renal uric acid stones in the adult

The aim of this study was to estimate uric acid renal stone prevalence rates of adults in different countries of the world. PubMed was searched for papers dealing with "urinary calculi and prevalence or composition" for the period from January 1996 to June 2016. Alternative searches were made to collect further information on specific topics. The prevalence rate of uric acid stones was computed by the general renal stone prevalence rate and the frequency of uric acid stones in each country. After the initial search, 2180 papers were extracted. Out of them, 79 papers were selected after the reading of the titles and of the abstracts. For ten countries, papers relating to both the renal stone prevalence in the general population and the frequency of uric stones were available. Additional search produced 13 papers that completed information on 11 more countries in 5 continents. Estimated prevalence rate of uric acid stones was >0.75% in Thailand, Pakistan, Saudi Arabia, Iran, South Africa (white population), United States and Australia; ranged 0.50-0.75% in Turkey, Israel, Italy, India (Southern), Spain, Taiwan, Germany, Brazil; and <0.50% in Tunisia, China, Korea, Japan, Caribe, South Africa (blacks), India (Northern). Climate and diet are major determinants of uric acid stone formation. A hot and dry climate increases fluid losses reducing urinary volume and urinary pH. A diet rich in meat protein causes low urinary pH and increased uric acid excretion. On the other hand, uric acid stone formation is frequently associated with obesity, metabolic syndrome and diabetes type 2 that are linked to dietary energy excess mainly from carbohydrate and saturated fat and also present with low urine pH values. An epidemic of uric acid stone formation could be if current nutritional trends will be maintained both in developed countries and in developing countries and the areas of greater climatic risk for the formation of uric acid stones will enlarge as result of the "global warming".

Urolithiasis and crohn's disease

Objective:

To present an updated description of the relation between Crohn's disease (CD) and Urolithiasis.

Patients and Methods:

A literature search for English-language original and review articles was conducted in Medline, Embase, and Cochrane databases in the month of December 2014 for papers either published or e-published up to that date, addressing the association between CD and urolithiasis as its consequence. All articles published in English language were selected for screening based on the following search terms: “CD,” “renal calculus,” “IBD,” and “urolithiasis.” We restricted the publication dates to the last 15 years (2000–2014).

Results:

In total, 901 patients were included in this review of which 95 were identified as having CD and urolithiasis simultaneously, for a total of 10.5%. Average age was 45.07 years old, irrespective of gender. 28.6% of patients received some kind of medical intervention without any kind of surgical technique involved, 50% of patients were submitted to a surgical treatment, and the remaining 21.4% were submitted to a combination of surgical and medical treatment. Urolithiasis and pyelonephritis incidence ranged from 4% to 23% with a risk 10–100 times greater than the risk for general population or for patients with UC, being frequent in patients with ileostomy and multiple bowel resections. We found that urolithiasis occurred in 95 patients from a total of 901 patients with CD (10.5%); 61.81% in men and 38.19% in women. Stone disease seems to present approximately 4–7 years after the diagnosis of bowel disease and CaOx seems to be the main culprit.

Conclusions:

CD is a chronic, granulomatous bowel disease, with urolithiasis as the most common extraintestinal manifestation (EIM), particularly frequent in patients submitted to bowel surgery. This complication needs to be recognized and addressed appropriately, especially in patients with unexplained renal dysfunction, abdominal pain, or recurrent urinary tract infection. We believe this study to be an updated valuable review as most data related to this kind of EIM refers to articles published before 2000, most of them before 1990. These patients need to be followed up with a specific prevention plan to eliminate or mitigate the risk factors for stone disease, aiming at preventing its formation and its complications, preserving renal function, reducing morbidity, and ultimately improving their quality of life.

Renal Involvement in Inflammatory Bowel Diseases

The prevalence of extraintestinal manifestations in inflammatory bowel diseases varies from 6% to 46%. The aetiology of extraintestinal manifestations remains unclear. There are theories based on an immunological response influenced by genetic factors. Extraintestinal manifestations can involve almost every organ system. They may originate from the same pathophysiological mechanism of intestinal disease, or as secondary complications of inflammatory bowel diseases, or autoimmune diseases susceptibility. The most frequently involved organs are the joints, skin, eyes, liver and biliary tract. Renal involvement has been considered as an extraintestinal manifestation and has been described in both Crohn's disease and ulcerative colitis. The most frequent renal involvements in patients with inflammatory bowel disease are nephrolithiasis, tubulointerstitial nephritis, glomerulonephritis and amyloidosis. The aim of this review is to evaluate and report the most important data in the literature on renal involvement in patients with inflammatory bowel disease. Bibliographical searches were performed of the MEDLINE electronic database from January 1998 to January 2015 with the following key words (all fields): (inflammatory bowel disease OR Crohn's disease OR ulcerative colitis) AND (kidney OR renal OR nephrotoxicity OR renal function OR kidney disease OR renal disease OR glomerulonephritis OR interstitial nephritis OR amyloidosis OR kidney failure OR renal failure) AND (5-aminosalicylic acid OR aminosalicylate OR mesalazine OR TNF-α inhibitors OR cyclosporine OR azathioprine OR drugs OR pediatric).

The management of patients with enteric hyperoxaluria

Enteric hyperoxaluria is a common occurrence in the setting of fat malabsorption, usually due to intestinal resection or intestinal bypass surgery. Enhanced intestinal absorption of dietary oxalate leads to elevated renal oxalate excretion, frequently in excess of 100 mg/d (1.14 mmol/d). Patients are at increased risk of urolithiasis and loss of kidney function from oxalate nephropathy. Fat malabsorption causes increased binding of diet calcium by free fatty acids, reducing the calcium available to precipitate diet oxalate. Delivery of unabsorbed bile salts and fatty acids to the colon increases colonic permeability, the site of oxalate hyper-absorption in enteric hyperoxaluria. The combination of soluble oxalate in the intestinal lumen and increased permeability of the colonic mucosa leads to hyperoxaluria. Dietary therapy consists of limiting oxalate and fat intake. The primary medical intervention is the use of oral oxalate binding agents such as calcium salts to reduce free intestinal oxalate levels. Bile acid sequestrants can be useful in patients with ileal resection and bile acid malabsorption. Oxalate degrading bacteria provided as probiotics are being investigated but as of yet, no definite benefit has been shown with currently available preparations. The current state of medical therapy and potential future directions will be summarized in this article.

[Urinary stones and bowel diseases: Systematic review]

PURPOSE

The aim of the study was to explain the relationship between urinary stones and bowel disease.

METHODS

A systematic review was performed on Medline, Embase and Cochrane using following keywords: urinary stones; urolithiasis; bowel; enteric and digestive. The literature selection was based on evidence and practical considerations.

RESULTS

Fifty-three articles were selected. Three types of urolthiasis are mainly involved in digestive pathologies: calcium oxalate stones, uric acid and ammonium acid urate stones. Bowel pathologies responsible for stone disease are divided into small bowel diseases, colonic lesions and lack of an oxalate degrading bacteria (Oxalobacter formigenes) in the intestinal flora. Resulting in a decreased urine output, pH, hyperoxaluria, hypocitraturia or a hypomagnesurie. Blood and urinary explorations are the basis of diagnostic management.

CONCLUSION

Bowel diseases can be responsible for urolthiasis. Understanding of the mechanisms, and metabolic evaluations can prevent recurrences. Increase fluid intake associated with specific supplementation and diet are the key of the treatment.

Incidence and Risk Factors for Urolithiasis in Patients with Crohn's Disease

BACKGROUND

The incidence of urinary tract calculi is thought to be higher in patients with inflammatory bowel disease (IBD) than that in the general population. However, few data are available about urolithiasis in patients with Crohn's disease (CD). We investigated the incidence of urolithiasis and the risk factors for urolithiasis in patients with CD.

METHODS

We examined the records of 387 patients with CD followed at Samsung Medical Center from July 2011 to June 2013. Evidence for the presence of calculi was obtained from radiologic findings (plain films, ultrasonography, or computed tomography), urinary colic symptoms, or a treatment history of urolithiasis after diagnosis of CD. Demographic variables, phenotype, concurrent medications, and previous CD-related surgery were analyzed.

RESULTS

Urinary tract calculi were found in 18 (4.7%) patients, which developed after the CD diagnosis. The incidence of urolithiasis in CD was 706 per 100,000 patient-years. Cox models with a time-dependent covariate showed that azathioprine (AZA)/6-mercaptopurine (6-MP) treatment (hazard ratio = 0.963; 95% CI: 0.931, 0.996; p = 0.030) was negatively associated with urolithiasis.

CONCLUSIONS

The annual incidence rate of urolithiasis in patients with CD was 0.7%. AZA/6-MP therapy was associated with a low risk of urolithiasis in these patients.

Urolithiasis and urinary tract infection among patients with inflammatory bowel disease: a review of US emergency department visits between 2006 and 2009

OBJECTIVE

To compare patients with inflammatory bowel disease (IBD) to a general population of urinary stone formers who present to US emergency departments with infected urolithiasis. Patients with IBD are at risk for both infection and stone formation, however studies investigating emergent urolithiasis presentations for this population are limited.

METHODS

Using the Nationwide Emergency Department Sample (2006-2009) we identified all patients presenting to the US emergency departments with a diagnosis of upper tract urolithiasis. We then described a subgroup with the concomitant diagnosis of IBD. We compared rates of urinary tract infection (UTI), sepsis, organ failure, admission, and mortality between the 2 groups. Using multivariate analysis, we determined whether or not IBD was a predictor of UTI, sepsis, and hospitalization.

RESULTS

Overall, 14,352 patients had concomitant IBD and urolithiasis. IBD patients with urolithiasis presented with infections (10.4% vs 9.1%; P <.001), sepsis (0.6% vs 0.2%; P <.001), and end-organ failure (6.3% vs 1.6%; P <.001) more frequently than non-IBD patients. They were also more likely to have characteristics independently associated with infection and sepsis, such as older age and female gender. In adjusted analyses, IBD was an independent predictor of infection (odds ratio [OR] = 1.3 [1.14-1.46]; P <.0001), sepsis (OR = 1.8 [1.09-2.92]; P <.0001), and admission (OR = 3.3 [3.04-3.64]; P <.0001).

CONCLUSION

IBD patients with urinary calculi have greater odds of UTI, renal failure, and sepsis compared to the general stone-forming population. The increased occurrence and severity of infected urolithiasis in this select group of patients warrants screening for stone disease, improved outpatient medical management, and early elective surgery for detected stones.

Nephropathy in dietary hyperoxaluria: A potentially preventable acute or chronic kidney disease

Hyperoxaluria can cause not only nephrolithiasis and nephrocalcinosis, but also renal parenchymal disease histologically characterized by deposition of calcium oxalate crystals throughout the renal parenchyma, profound tubular damage and interstitial inflammation and fibrosis. Hyperoxaluric nephropathy presents clinically as acute or chronic renal failure that may progress to end-stage renal disease (ESRD). This sequence of events, well recognized in the past in primary and enteric hyperoxalurias, has also been documented in a few cases of dietary hyperoxaluria. Estimates of oxalate intake in patients with chronic dietary hyperoxaluria who developed chronic kidney disease or ESRD were comparable to the reported average oxalate content of the diets of certain populations worldwide, thus raising the question whether dietary hyperoxaluria is a primary cause of ESRD in these regions. Studies addressing this question have the potential of improving population health and should be undertaken, alongside ongoing studies which are yielding fresh insights into the mechanisms of intestinal absorption and renal excretion of oxalate, and into the mechanisms of development of oxalate-induced renal parenchymal disease. Novel preventive and therapeutic strategies for treating all types of hyperoxaluria are expected to develop from these studies.

Secondarily infected nonstruvite urolithiasis: a prospective evaluation

OBJECTIVE

To characterize patients who form nonstruvite stones associated with infection (secondarily infected calculi), and to define the bacteria associated with these.

MATERIALS AND METHODS

Patients undergoing percutaneous nephrolithotomy were prospectively recruited. Medical records were reviewed, and stones were analyzed using micro computed tomography and infrared spectroscopy. A fragment of each stone was sent for bacterial culture. Patients were categorized by stone culture results (SC ±) and the presence of struvite (ST ±). The Fisher exact test was used for comparison of proportion. Sterility of intraoperative SC was established with independently collected controls.

RESULTS

In total, 125 patients were enrolled: 24 SC+/ST-, 19 SC+/ST+, and 82 SC-/ST-. Proportions of patients with prior urologic surgery, diabetes, and immunodeficiency were similar between groups. Patients with neurogenic bladder were more likely to have SC+/ST+ stones or SC+/ST- stones than SC-/ST- stones (26% vs 8% vs 0%, respectively; P <.01). Among patients with metabolic evaluations, hypocitraturia was found in 31.6% (6 of 19) SC+/ST- patients, 46.7% (7 of 15) SC+/ST+ patients, and 26.0% (19 of 73) of SC-/ST- patients (P = .28). Approximately 40% of cultured organisms in the secondarily infected calculi possessed urease and another 40% citrate lyase activities.

CONCLUSION

Secondarily infected stones were detected in approximately 20% of this surgical cohort and may be more common than previously appreciated. Neurogenic bladder appeared to predispose patients to either struvite or secondarily infected stones. The role of bacterial infection in stone formation is unclear but may include alteration of urinary components, acting as a nidus for crystallization, or inducing inflammation.

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

BACKGROUND AND PURPOSE

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.

MATERIALS AND METHODS

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.

RESULTS

[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.

CONCLUSIONS

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.

Kidney stones: an update on current pharmacological management and future directions

INTRODUCTION

Kidney stones are a common problem worldwide with substantial morbidities and economic costs. Medical therapy reduces stone recurrence significantly. Much progress has been made in the last several decades in improving therapy of stone disease.

AREAS COVERED

This review discusses i) the effect of medical expulsive therapy on spontaneous stone passage, ii) pharmacotherapy in the prevention of stone recurrence and iii) future directions in the treatment of kidney stone disease.

EXPERT OPINION

Fluid intake to promote urine volume of at least 2.5 L each day is essential to prevent stone formation. Dietary recommendations should be adjusted based on individual metabolic abnormalities. Properly dosed thiazide treatment is the standard therapy for calcium stone formers with idiopathic hypercalciuria. Potassium alkali therapy is considered for hypocitraturia, but caution should be taken to prevent potential risk of calcium phosphate stone formation. For absorptive hyperoxaluria, low oxalate diet and increased dietary calcium intake are recommended. Pyridoxine has been shown effective in some cases of primary hyperoxaluria type I. Allopurinol is used in calcium oxalate stone formers with hyperuricosuria. Treatment of cystine stones remains challenging. Tiopronin can be used if urinary alkalinization and adequate fluid intake are insufficient. For struvite stones, complete surgical removal coupled with appropriate antibiotic therapy is necessary.

Frequency and risk factors of renal insufficiency in inflammatory bowel disease inpatients

BACKGROUND

Renal involvement in patients with inflammatory bowel disease (IBD) has been well documented. However, there was a paucity of data on the frequency of renal insufficiency and its risk factors in this patient population. The aim of the study was to determine the frequency and factors associated with renal insufficiency within IBD inpatients.

METHODS

This case-control study was conducted on both Crohn's disease and ulcerative colitis inpatients in our tertiary care center from 2009 to 2010. Patients were identified as having renal insufficiency by the criterion of glomerular filtration rate < 60 mL/min/1.73 m. The glomerular filtration rate was further assessed against normal reference ranges. Risk factors for renal insufficiency were evaluated by univariable and multivariable analyses.

RESULTS

A total of 251 eligible patients were included. The frequency of renal insufficiency was 15.9% (95% confidence interval: 11.4-20.5), with 40 patients having a glomerular filtration rate <60 mL/min/1.73 m. Univariable analysis demonstrated several possible risk factors, including older age at admission (42.0 ± 16.2 years versus 57.6 ± 13.3 years, P < 0.001), and a longer median duration of IBD (9.0 years [interquartile range: 3.5-20.0] versus 25.0 years [interquartile range: 15.0-36.0], P < 0.001). The multivariable logistic analysis demonstrated that for every 5-year increase in age at the time of admission, the likelihood of having renal insufficiency increased by 30%.

CONCLUSION

Acute or chronic renal sufficiency in IBD inpatients was common, especially in elderly. Acute renal insufficiency can be medically reversed if properly treated. We recommend that renal function be closely monitored in IBD inpatients.

Nephrolithiasis in patients with inflammatory bowel disease in the community

Background

Inflammatory bowel disease (IBD) has been associated with renal stone formation. The objective of this study was to determine prospectively the prevalence of nephrolithiasis in a community-based population of patients with IBD and to analyze factors associated with renal calculus formation.

Methods

Screening renal ultrasound was performed in a well characterized cohort of patients seen between 2009 and 2012 at an IBD clinic. We enrolled 168 patients, including 93 with Crohn’s disease and 75 with ulcerative colitis. Clinical and phenotypic variables associated with asymptomatic nephrolithiasis were determined.

Results

Nephrolithiasis was detected in 36 patients with Crohn’s disease and in 28 patients with ulcerative colitis (38% for both). Although none of the patients had been previously hospitalized for symptomatic nephrolithiasis, nine with Crohn’s disease and five with ulcerative colitis had recurrent urinary tract infections or hydronephrosis. In patients with Crohn’s disease, ileocolonic (L3) disease was associated with a greater risk of nephrolithiasis than was ileal (L1) or colonic (L2) disease (odds ratio [OR] 2.3, 95% confidence interval [CI] 1.8–7). Active ulcerative colitis (regardless of severity) represented a significant risk factor for formation of renal calculi (OR 4.2, 95% CI 1.1–15, P = 0.02).

Conclusion

In surgery-naïve patients with IBD in the community, asymptomatic nephrolithiasis is common and should be considered when renal dysfunction or infection is detected.

The trigger-maintenance model of persistent mild to moderate hyperoxaluria induces oxalate accumulation in non-renal tissues

Persistent mild to moderate hyperoxaluria (PMMH) is a common side effect of bariatric surgery. However, PMMH's role in the progression to calcium oxalate (CaOx) urolithiasis and its potential effects on non-renal tissues are unknown. To address these points, a trigger + maintenance (T + Mt) model of PMMH was developed in rats (Experiment 1). The trigger was an i.p. injection of PBS (TPBS) or 288 μmol sodium oxalate (T288). Maintenance (Mt) was given via minipumps dispensing PBS or 7.5-30 μmol potassium oxalate/day for 28 days. Urinary oxalate ranged from 7.7 ± 0.8 μmol/day for TPBS + MtPBS to 18.2 ± 1.5 μmol/day for T288 + Mt30 (p ≤ 0.0005). All rats receiving T288 developed CaOx nephrocalcinosis, and many developed 'stones'. This was also true for Mt doses that did not elevate urinary oxalate above that of TPBS + MtPBS (p > 0.1) and for rats that did not have a detectable surge in urinary oxalate post T288. When TPBS was administered, CaOx nephrocalcinosis did not develop regardless of the Mt dose even if urinary oxalate was elevated compared to TPBS + MtPBS (p ≤ 0.0005). One of the risks associated with PMMH is oxalate accumulation within tissues. Hence, in a second set of experiments (Experiment 2) different doses of oxalate (Mt0.05, Mt15, Mt30) labeled with (14)C-oxalate ((14)C-Ox) were administered by minipump for 13 days. Tissues were harvested and (14)C-Ox accumulation assessed by scintillation counting. (14)C-Ox accumulated in a dose dependent manner (p ≤ 0.004) in bone, kidney, muscle, liver, heart, kidney, lungs, spleen, and testis. All these tissues exhibited (14)C-Ox concentrations higher (p ≤ 0.05) than the plasma. Extrapolation of our results to patients suggests that PMMH patients should take extra care to avoid dietary-induced spikes in oxalate excretion to help prevent CaOx nephrocalcinosis or stone development. Monitoring for oxalate accumulation within tissues susceptible to damage by oxalate or CaOx crystals may also be required.

Determinants of urolithiasis in patients with intestinal fat malabsorption

OBJECTIVE

To investigate the determinants of urinary stone formation in patients with fat malabsorption, because, although the prevalence of urolithiasis is greater in patients with intestinal diseases, the pathogenetic mechanisms and risk factors associated with urolithiasis in this population remain partially unsolved.

MATERIALS AND METHODS

The present study retrospectively analyzed the determinants of urolithiasis in 51 patients with fat malabsorption due to different intestinal diseases. Anthropometric, clinical, blood, 24-hour urinary parameters, and dietary intake were assessed.

RESULTS

The resection rate (ie, pancreatic and/or bowel resection) differed significantly between stone formers (SF; n=10) and nonstone formers (NSF; n=41; 70% vs 29%; P=.027). Urinary citrate was lower (1.606±1.824 vs 3.156±1.968 mmol/24 h; P=.027), while oxalate excretion (0.659±0.292 vs 0.378±0.168 mmol/24 h; P=.002) and the relative supersaturation of calcium oxalate were greater in SF than NSF (8.16±4.61 vs 3.94±2.93; P=.003). Total cholesterol and low-density lipoprotein cholesterol, but also high-density lipoprotein cholesterol, plasma β-carotene, and vitamin E concentrations, were significantly diminished, whereas serum aspartate aminotransferase activity was significantly greater in SF compared with NSF. Binary logistic regression analysis revealed resection status as a major extrarenal risk factor for stone formation (odds ratio 5.639).

CONCLUSION

Increased urinary oxalate and decreased citrate excretion, probably resulting from pancreatic and/or bowel resection with mainly preserved colon, were identified as the most crucial urinary risk factors for stone formation in patients with fat malabsorption. The findings suggest that hyperoxaluria predominantly results from increased colonic permeability for oxalate due to disturbed bile acid metabolism. The impaired status of fat-soluble antioxidants β-carotene and vitamin E indicates severe malabsorptive states associated with an enhanced stone-forming propensity.

Uric acid stones and hyperuricosuria

Recent work has highlighted the strong relationships among obesity, diabetes, and the metabolic syndrome as causes of low urinary pH. Low urinary pH in turn is the major urinary risk factor for uric acid stones. Unlike calcium stones, uric acid stones can be dissolved and easily prevented with adequate urinary alkalinization. Recognizing the relevant risk factors should lead to increased identification of these radiolucent stones. The cornerstone of therapy is raising urinary pH; xanthine dehydrogenase inhibitors should be used only when urinary alkalinization cannot be achieved.

Net intestinal transport of oxalate reflects passive absorption and SLC26A6-mediated secretion

Mice lacking the oxalate transporter SLC26A6 develop hyperoxalemia, hyperoxaluria, and calcium-oxalate stones as a result of a defect in intestinal oxalate secretion, but what accounts for the absorptive oxalate flux remains unknown. We measured transepithelial absorption of [(14)C]oxalate simultaneously with the flux of [(3)H]mannitol, a marker of the paracellular pathway, across intestine from wild-type and Slc26a6-null mice. We used the anion transport inhibitor DIDS to investigate other members of the SLC26 family that may mediate transcellular oxalate absorption. Absorptive flux of oxalate in duodenum was similar to mannitol, insensitive to DIDS, and nonsaturable, indicating that it is predominantly passive and paracellular. In contrast, in wild-type mice, secretory flux of oxalate in duodenum exceeded that of mannitol, was sensitive to DIDS, and saturable, indicating transcellular secretion of oxalate. In Slc26a6-null mice, secretory flux of oxalate was similar to mannitol, and no net flux of oxalate occurred. Absorptive fluxes of both oxalate and mannitol varied in parallel in different segments of small and large intestine. In epithelial cell lines, modulation of the charge selectivity of the claudin-based pore pathway did not affect oxalate permeability, but knockdown of the tight-junction protein ZO-1 enhanced permeability to oxalate and mannitol in parallel. Moreover, formation of soluble complexes with cations did not affect oxalate absorption. In conclusion, absorptive oxalate flux occurs through the paracellular "leak" pathway, and net absorption of dietary oxalate depends on the relative balance between absorption and SLC26A6-dependent transcellular secretion.