Papillary calcifications: a new prognostic factor in idiopathic calcium oxalate urolithiasis

Non-contrast CT attenuation value of renal papilla is a novel predictor of recurrence in kidney stone disease

In calcium stone formers, most stones grow attached to Randall's plaque, which can be identified by measuring the computed tomography (CT) attenuation value of renal papilla. We hypothesized that the CT attenuation value of renal papilla can predict the severity (recurrent or multiple stone former) and recurrence of the stone disease. We retrospectively reviewed the charts of 180 calcium oxalate stone formers who underwent non-contrast CT and 24-hour urine chemistry in our hospital between September 2012 and November 2021. Two observers independently measured the Hounsfield unit (HU) of the renal papilla and classified the patients into the low-HU and the high-HU value groups according to the median value (38.9 HU). The proportion of recurrent and multiple stone formers were similar between the low-HU group and the high-HU group (70.0% vs. 65.6%, 71.1% vs. 74.2%, respectively). There were also no significant differences in urinary volume, urinary excretions of each constituent, or AP(CaOx) index between the two groups. On the other hand, the recurrence rate in the high-HU value group (0.10 events/person/year) was significantly higher than that in the low-HU value group (0 events/person/year, p = 0.03). Multivariate analysis revealed that high-HU value was an independent predictor of stone recurrence (OR 1.90, 95% CI 1.00-3.64, p = 0.04) as well as medical prophylaxis. The results of this study suggest that HU value of renal papilla is a useful predictor of recurrence of stone disease.

2022 Recommendations of the AFU Lithiasis Committee: Endoscopic description of renal papillae and stones

Endoscopic observation is performed during treatments by flexible ureteroscopy to differentiate in situ between renal papillary abnormalities and stones based on their concordance with Daudon's morphological/composition descriptions adapted to endoscopy. These intraoperative visual analyses are now an integral part of the urinary stone disease diagnostic approach in addition to the morphological/structural and spectrophotometric analysis that remains the reference exam, but that loses information on the stone component representativeness due to the development of in situ laser lithotripsy. These are the first practical recommendations on the endoscopic description of renal papillae and stones. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendations (CPR) and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis [EAU Guidelines on urolithiasis. 2022]) and their adaptability to the French context.

Pancreatic exocrine insufficiency is a risk factor for kidney stones in patients with chronic pancreatitis

INTRODUCTION

Most patients with chronic pancreatitis (CP) develop pancreatic exocrine insufficiency (PEI) over the course of the disease. PEI may lead to hyperoxaluria and development of urinary oxalate stones. It has been postulated that the patients with CP may be at increased risk of kidney stone formation, but the data is scarce. We aimed to estimate incidence and risk factors for nephrolithiasis in a Swedish cohort of patients with CP.

PATIENTS AND METHODS

We performed retrospective analysis of an electronical medical database of patients diagnosed with definite CP during 2003-2020. We excluded patients <18 years of age, those with missing relevant data in medical charts, patients with probable CP (according to the M-ANNHEIM classification system) and those in whom kidney stones were diagnosed before CP diagnosis.

RESULTS

Some 632 patients with definite CP were followed over a median of 5.3 (IQR 2.4-6.9) years. There were 41 (6.5%) patients diagnosed with kidney stones, of whom 33 (80.5%) were symptomatic. Comparing to patients without kidney stones, patients with nephrolithiasis were older, with median age of 65 (IQR 51-72) years, and a male predominance (80% vs 63%). Cumulative incidence of kidney stones was 2.1%, 5.7%, 12.4% and 16.1% at 5, 10, 15, and 20 years after CP diagnosis, respectively. Multivariable cause-specific Cox regression analysis revealed PEI as independent risk factor for nephrolithiasis (adjusted HR 4.95, 95%CI 1.65-14.84; p = 0.004). Another risk factors were increase in BMI (aHR 1.16 95% CI 1.04-1.30; p = 0.001 per unit increment), and a male sex (4.51, 95% CI 1.01-20.3, p = 0.049).

CONCLUSION

PEI and increase in BMI are risk factors for kidney stone development in patients with CP. Male CP patents are particularly at increased risk of nephrolithiasis. This should be taken into consideration in general clinical approach to raise awareness among patients and medical workers.

Endoscopic Papillary Abnormalities and Stone Recognition (EPSR) during Flexible Ureteroscopy: A Comprehensive Review

Introduction: The increasing efficiency of the different lasers and the improved performance of endoscopic devices have led to smaller stone fragments that impact the accuracy of microscopic evaluation (morphological and infrared). Before the stone destruction, the urologist has the opportunity to analyze the stone and the papillary abnormalities endoscopically (endoscopic papillary recognition (EPR) and endoscopic stone recognition (ESR)). Our objective was to evaluate the value for those endoscopic descriptions. Methods: The MEDLINE and EMBASE databases were searched in February 2021 for studies on endoscopic papillary recognition and endoscopic stone recognition. Results: If the ESR provided information concerning the main crystallization process, EPR provided information concerning the origin of the lithogenesis and its severity. Despite many actual limitations, those complementary descriptions could support the preventive care of the stone formers in improving the diagnosis of the lithogenesis mechanism and in identifying high-risk stone formers. Conclusion: Until the development of an Artificial Intelligence recognition, the endourologist has to learn EPSR to minimize the distortion effect of the new lasers on the stone analysis and to improve care efficiency of the stone formers patients.

Relationship of endoscopic lesions of the renal papilla with type of renal stone and 24 h urine analysis

Background

Our purpose was to study the relationship of the 3 different types of endoscopic calcifications of the renal papilla (Randall’s plaque, intratubular calcification, papillary crater) with the type of stone and urine analysis.

Methods

This prospective study examined 41 patients (age range: 18 to 80 years) who received retrograde intrarenal surgery (RIRS) for renal lithiasis (mean stone size: 15.3 ± 7.2 mm). The renal papilla injuries were endoscopically classified as Randall’s plaque, intratubular calcification, or papillary crater. Calculi were classified as uric acid, calcium oxalate monohydrate (COM; papillary and cavity), calcium oxalate dihydrate (COD), or calcium phosphate (CP). A 24 h urine analysis of calcium, oxalate, citrate, phosphate, and pH was performed in all patients. The relationship of each type of papillary injury with type of stone and urine chemistry was determined. Fisher’s exact test and Student’s t-test were used to determine the significance of relationships, and a p value below 0.05 was considered significant.

Results

The most common injury was tubular calcification (78%), followed by Randall’s plaque (58%), and papillary crater (39%). There was no significant relationship of Randall’s plaque with type of stone. However, endoscopic intratubular calcification (p = 0.025) and papillary crater (p = 0.041) were more common in patients with COD and CP stones. There were also significant relationships of papillary crater with hypercalciuria (p = 0.036) and hyperoxaluria (p = 0.024), and of Randall’s plaque with hypocitraturia (p = 0.005).

Conclusions

There are certain specific relationships between the different types of papillary calcifications that were endoscopically detected with stone chemistry and urine analysis. COD and CP stones were associated with endoscopic tubular calcifications and papillary craters. Hypercalciuria was associated with tubular calcification, and hypocitraturia was associated with Randall’s plaque.

Association between chronic pancreatitis and urolithiasis: A population-based cohort study

Purpose

Chronic pancreatitis (CP) can cause fat or bile acid malabsorption due to exocrine insufficiency. Fat or bile acid malabsorption has been reported to increase the risk of urolithiasis through increased intestinal oxalate absorption. However, no studies have reported an association between CP and urolithiasis.

Methods

We identified 15,848 patients (age: ≥20 years) diagnosed as having CP between 2000 and 2010 from the National Health Insurance Research Database as the study cohort. Beneficiaries without a history of CP were randomly selected and propensity-matched with the study cohort in a 1:4 ratio according to age; sex; comorbidities of hyperlipidemia, diabetes, obesity, hypertension, chronic obstructive pulmonary disease, alcohol-related illness, stroke, and coronary artery disease; and the index date. The prevalence of inflammatory bowel disease (0.44%), hyperparathyroidism (0.10%), or end stage renal disease (1.55%) in CP patients was low, but these comorbidities were also considered in the analysis. All patients were followed until the end of 2011 or withdrawal from the National Health Insurance program to determine the incidence of urolithiasis.

Results

The cumulative incidence of urolithiasis was higher in the CP cohort than that in the non-CP cohort (log-rank test, P < 0.001) with a 1.89-fold risk of urolithiasis (95% confidence interval [CI] = 1.74–2.06). The prevalence of CP was higher in men (81.9%) and in patients younger than 49 years (63.5%; mean age: 48.5 ± 15.3 years). CP was associated with the development of urolithiasis in each age group (≤49 years: aHR = 2.00, 95% CI = 1.81–2.22; 50–64 years: aHR = 1.71, 95% CI = 1.40–2.09; ≥65 years: aHR = 1.54, 95% CI = 1.20–1.98) and each sex (women: aHR = 2.10, 95% CI = 1.67–2.66; men; aHR = 1.86, 95% CI = 1.70–2.04). Among the patients without comorbidities, the rate of urolithiasis increased from 2.93/1,000 person-years in non-CP patients to 8.28/1,000 person-years in CP patients. Among the patients with comorbidities, the rate of urolithiasis increased from 6.12/1,000 person-years in non-CP patients to 10.9/1,000 person-years in CP patients. The contribution of CP to the relative risk of urolithiasis was greater in patients without comorbidities (without comorbidities: aHR = 2.81, 95% CI = 2.30–3.44) than in those with comorbidities (aHR = 1.76, 95% CI = 1.61–1.94).

Conclusion

CP is associated with urolithiasis in this population-based cohort study. The contribution of CP to the relative risk of urolithiasis was even greater in patients with a lower risk of urolithiasis, such as those without other comorbidities. Our findings warrant a survey and education on urolithiasis for patients with CP.

Metabolic diagnosis and medical prevention of calcium nephrolithiasis and its systemic manifestations: a consensus statement

BACKGROUND

Recently published guidelines on the medical management of renal stone disease did not address relevant topics in the field of idiopathic calcium nephrolithiasis, which are important also for clinical research.

DESIGN

A steering committee identified 27 questions, which were proposed to a faculty of 44 experts in nephrolithiasis and allied fields. A systematic review of the literature was conducted and 5216 potentially relevant articles were selected; from these, 407 articles were deemed to provide useful scientific information. The Faculty, divided into working groups, analysed the relevant literature. Preliminary statements developed by each group were exhaustively discussed in plenary sessions and approved.

RESULTS

Statements were developed to inform clinicians on the identification of secondary forms of calcium nephrolithiasis and systemic complications; on the definition of idiopathic calcium nephrolithiasis; on the use of urinary tests of crystallization and of surgical observations during stone treatment in the management of these patients; on the identification of patients warranting preventive measures; on the role of fluid and nutritional measures and of drugs to prevent recurrent episodes of stones; and finally, on the cooperation between the urologist and nephrologist in the renal stone patients.

CONCLUSIONS

This document has addressed idiopathic calcium nephrolithiasis from the perspective of a disease that can associate with systemic disorders, emphasizing the interplay needed between urologists and nephrologists. It is complementary to the American Urological Association and European Association of Urology guidelines. Future areas for research are identified.

Recent advances in understanding and managing urolithiasis

During the last few years, there has been relevant progress in both understanding and managing urolithiasis. Our knowledge of stone formation has changed; although the importance of urine biochemistry was questioned by several investigators years ago, the decisive role of cellular processes (induced by oxidative stress) and the renal papilla has only recently been generally accepted as the most important step in stone formation. For calcium oxalate urolithiasis, the formation of papillary calcifications plays a key role and is of prognostic relevance. Further research has to concentrate on these aspects of preventing urolithiasis. Stone prevention (metaphylaxis) is a major issue when considering the burden it places on healthcare systems. An effective metaphylaxis could lower the cost of stone therapy significantly. For uric acid urolithiasis, so far there is only preliminary information available showing that papillary plaques are not as important as they are in calcium oxalate urolithiasis. Concerning stone management, endourology has improved stone therapy significantly during the last few years. Morbidity decreased and success (stone-free) rates increased. Therefore, the indications for extracorporeal shockwave lithotripsy (ESWL) narrowed. ESWL, however, still has its place in stone therapy. There is not one single treatment modality that is equally effective for all situations. It is important to observe the differential indications for different stones depending on size, localization, and composition.

Impact of metabolic syndrome and its components on kidney stone in aging Taiwanese males

OBJECTIVES

Metabolic syndrome (MtS) and kidney stone are two common aging diseases with male dominant. This is the first study regarding the potential impact of MtS and its components on kidney stone in aging Chinese population.

METHODS

A total of 694 males with a mean age of 55.6 years were enrolled. The definition of MtS was according to the modified criteria developed by the Bureau of Health Promotion in Taiwan. Subjects were classified as having a disease of kidney stones according to diagnosis by a physician with available medical records or evidence from ultrasonography judged by an investigator of urologist.

RESULTS

Using age-adjusted multivariate logistic regression analysis, our results showed that subjects with kidney stone had significantly higher prevalence of MtS (p = 0.04, OR = 1.74, 95% CI: 1.0 1-3.00). The presence of MtS had significant correlation with kidney stone (p = 0.01, OR = 1.83, 95% CI: 1.1 4-2.93), which were associated with the increment of MtS components (p < 0.01). After adjusting for age and testosterone level, abnormal blood pressure (BP) was the most significantly independent component of MtS for kidney stone among the MtS components (p < 0.01, OR = 2.81, 95% CI: 1.46-5.39).

CONCLUSIONS

In aging Taiwanese males, the presence of MtS and its components are strongly associated with kidney stone. Abnormal BP is the most significant risk component of MtS for kidney stone.

The association of metabolic syndrome and urolithiasis

There has been an increasing prevalence of kidney stones over the last 2 decades worldwide. Many studies have indicated a possible association between metabolic syndrome and kidney stone disease, particularly in overweight and obese patients. Many different definitions of metabolic syndrome have been suggested by various organizations, although the definition by the International Diabetes Federation (IDF) is universally considered as the most acceptable definition. The IDF definition revolves around 4 core components: obesity, dyslipidemia, hypertension, and diabetes mellitus. Several hypotheses have been proposed to explain the pathophysiology of urolithiasis resulting from metabolic syndrome, amongst which are the insulin resistance and Randall's plaque hypothesis. Similarly the pathophysiology of calcium and uric acid stone formation has been investigated to determine a connection between the two conditions. Studies have found many factors contributing to urolithiasis in patients suffering from metabolic syndrome, out of which obesity, overweight, and sedentary lifestyles have been identified as major etiological factors. Primary and secondary prevention methods therefore tend to revolve mainly around lifestyle improvements, including dietary and other preventive measures.