Optimal non-invasive treatment of 1–2.5 cm radiolucent renal stones: oral dissolution therapy, shock wave lithotripsy or combined treatment—a randomized controlled trial

Potassium sodium hydrogen citrate intervention on gut microbiota and clinical features in uric acid stone patients

The high recurrence rate of renal uric acid stone (UAS) poses a significant challenge for urologists, and potassium sodium hydrogen citrate (PSHC) has been proven to be an effective oral dissolution drug. However, no studies have investigated the impact of PSHC on gut microbiota and its metabolites during stone dissolution therapy. We prospectively recruited 37 UAS patients and 40 healthy subjects, of which 12 patients completed a 3-month pharmacological intervention. Fasting vein blood was extracted and mid-stream urine was retained for biochemical testing. Fecal samples were collected for 16S ribosomal RNA (rRNA) gene sequencing and short chain fatty acids (SCFAs) content determination. UAS patients exhibited comorbidities such as obesity, hypertension, gout, and dyslipidemia. The richness and diversity of the gut microbiota were significantly decreased in UAS patients, Bacteroides and Fusobacterium were dominant genera while Subdoligranulum and Bifidobacterium were poorly enriched. After PSHC intervention, there was a significant reduction in stone size accompanied by decreased serum uric acid and increased urinary pH levels. The abundance of pathogenic bacterium Fusobacterium was significantly downregulated following the intervention, whereas there was an upregulation observed in SCFA-producing bacteria Lachnoclostridium and Parasutterella, leading to a significant elevation in butyric acid content. Functions related to fatty acid synthesis and amino acid metabolism within the microbiota showed upregulation following PSHC intervention. The correlation analysis revealed a positive association between stone pathogenic bacteria abundance and clinical factors for stone formation, while a negative correlation with SCFAs contents. Our preliminary study revealed that alterations in gut microbiota and metabolites were the crucial physiological adaptation to PSHC intervention. Targeted regulation of microbiota and SCFA holds promise for enhancing drug therapy efficacy and preventing stone recurrence. KEY POINTS: • Bacteroides and Fusobacterium were identified as dominant genera for UAS patients • After PSHC intervention, Fusobacterium decreased and butyric acid content increased • The microbiota increased capacity for fatty acid synthesis after PSHC intervention.

Prevention, diagnosis, and treatment of urolithiasis in geriatric patients - differences, similarities and caveats in comparison to the general population

PURPOSE OF REVIEW

Purpose of the review is to address management and prevention of urolithiasis in elderly patients examining the dynamic interplay between general measures, dietary adjustments, lifestyle modifications, and targeted pharmacological and/ or surgical interventions. The goal is to provide understanding of the evolving strategies required for effective urolithiasis prevention in the geriatric population.

RECENT FINDINGS

Age-specific diagnostic considerations are necessary because urolithiasis in the elderly population is characterized by bigger stones, greater peri-operative risks, and heightened symptom severity. When comorbidities are present, conservative treatments - especially analgesia - provide difficulties. Surgical procedures prove to be safe and effective, with complication rates and practical application comparable to younger cohorts. Prevention approaches that include lifestyle changes and the investigation of novel pharmaceutical options such as sodium-dependent glucose co-transporter 2 (SGLT-2)-inhibitors are promising in the management of urolithiasis in the elderly population.

SUMMARY

Our review offers a thorough investigation of urolithiasis in the elderly population, elucidating distinct clinical manifestations, complex diagnostic issues, and treatment implications. The safety and effectiveness of ureteroscopy in older patients, as well as the possible prophylactic function of SGLT-2-I, offer crucial insights for clinicians. Subsequent studies are necessary to enhance age-specific therapies, addressing the distinct obstacles presented by urolithiasis in the elderly population within this rapidly growing demographic.

The role of the general practictioner in the management of urinary calculi

BACKGROUND

The prevalence of kidney stones tends to increase worldwide due to dietary and climate changes. Disease management involves a high consumption of healthcare system resources which can be reduced with primary prevention measures and prophylaxis of recurrences. In this field, collaboration between general practitioners (GPs) and hospitals is crucial.

METHODS

a panel composed of general practitioners and academic and hospital clinicians expert in the treatment of urinary stones met with the aim of identifying the activities that require the participation of the GP in the management process of the kidney stone patient.

RESULTS

Collaboration between GP and hospital was found crucial in the treatment of renal colic and its infectious complications, expulsive treatment of ureteral stones, chemolysis of uric acid stones, long-term follow-up after active treatment of urinary stones, prevention of recurrence and primary prevention in the general population.

CONCLUSIONS

The role of the GP is crucial in the management and prevention of urinary stones. Community hospitals which are normally led by GPs in liaison with consultants and other health professional can have a role in assisting multidisciplinary working as extended primary care.

Predictors of stone-free rate after a single-session extracorporeal shockwave lithotripsy for a single kidney stone measuring 10 to 20 mm: A private center experience

Background

Despite the continuous update of guidelines for the management of kidney stones, the ability to predict a successful response to extracorporeal shockwave lithotripsy (SWL) remains a topic of research. This is due to the need to refine the decision making in the context of technological advancements and current pandemics. This study aimed to determine the predictors of stone-free rate (SFR) after single-session SWL in adult patients with a single kidney stone 10 to 20 mm in diameter.

Materials and methods

A retrospective review of the records of patients with a single kidney stone 10 to 20 mm in diameter was performed at a private SWL center from December 2019 to February 2021. Univariate and multivariate analyses were performed for stone- and patient-related factors, using the Student t and Mann-Whitney U tests for the quantitative variables and the Fisher exact and Pearson correlation tests for the qualitative variables.

Results

A total of 138 patients were eligible for this study, including 92 men and 46 women. The mean age was 38.6 ± 12.4 years, and the mean body mass index (BMI) was 25.9 ± 3.4 kg/m2. Four weeks after SWL, 120 patients (87%) were free of stones, and 18 (13%) needed further treatment. Univariate analyses showed that SFR was negatively correlated with increased BMI (p = 0.0001), maximum stone length (p = 0.0001), transverse diameter of the stone (p = 0.0001), number of shocks per session (p = 0.052), and Hounsfield unit (HU) (p = 0.0001). Multivariate analysis revealed that HU (p = 0.009), maximum stone length (p = 0.01), BMI (p = 0.000), and presence of double-J stent (p = 0.034) were independent risk factors for failure of single-session SWL in the treatment of kidney stones 10 to 20 mm in diameter. The estimated average cost per case was USD 450.5.

Conclusions

Increased HU, maximum stone length, BMI, and presence of double-J stents were independent risk factors for low SFR after single-session SWL for a kidney stone 10 to 20 mm in diameter. The cost of SWL remains an advantage in the private sector.

Comparison potassium sodium hydrogen citrate with sodium bicarbonate in urine alkalization: a prospective crossover-controlled trial

PURPOSE

Excessive alkalization will increase the incidence of nephrolithiasis. Sodium bicarbonate (NaHCO₃) and potassium sodium hydrogen citrate (PSHC) are commonly used drugs for urinary alkalization. We designed a trial to compare PSHC with NaHCO₃ in the urine alkalization for the Chinese healthy participants and to explore the effects of PSHC and NaHCO₃ on circadian rhythms of urine pH value.

METHOD

This study was a prospective, crossover, randomized, controlled trial, in which a total of 34 healthy volunteers participated in two study phases and took PSHC and NaHCO₃ at the maintenance dose, respectively.

RESULT

The average level of urine pH of PSHC participants in 24 h was significantly higher than that of NaHCO₃ (P < 0.001). The urine pH value of participants taking PSHC and NaHCO₃ or under physiological conditions showed significant variation in 24 h (P < 0.05) and fitted to a mathematical model (Fourier series). Under physiological conditions, the average urine pH value in the daytime was higher than that in the night, and reached the peak at about 10:00, 16:00, and 22:00. The peak of urine pH at 24 h after taking PSHC and NaHCO₃ was both higher than the baseline. The peak time of urine pH and the curve trend were similar, but the peak value in PSHC group was significantly higher than that in NaHCO₃ group.

CONCLUSIONS

There was a circadian rhythm of urine pH value under physiological conditions. PSHC was more effective in urinary alkalization than NaHCO₃ at the current maintenance oral dose and administration time without changing the rhythm of urine pH value.

CLINICAL TRIAL REGISTRATION

NCT04352153.

Imaging in stone diagnosis and surgical planning

PURPOSE OF REVIEW

Radiological imaging techniques and applications are constantly advancing. This review will examine modern imaging techniques in the diagnosis of urolithiasis and applications for surgical planning.

RECENT FINDINGS

The diagnosis of urolithiasis may be done via plain film X-ray, ultrasound (US), or contrast tomography (CT) scan. US should be applied in the workup of flank pain in emergency rooms and may reduce unnecessary radiation exposure. Low dose and ultra-low-dose CT remain the diagnostic standard for most populations but remain underutilized. Single and dual-energy CT provide three-dimensional imaging that can predict stone-specific parameters that help clinicians predict stone passage likelihood, identify ideal management techniques, and possibly reduce complications. Machine learning has been increasingly applied to 3-D imaging to support clinicians in these prognostications and treatment selection.

SUMMARY

The diagnosis and management of urolithiasis are increasingly personalized. Patient and stone characteristics will support clinicians in treatment decision, surgical planning, and counseling.

Medical Treatment and Prevention of Urinary Stone Disease

The pathophysiology underlying urinary stone formation remains an area of active investigation. There are many pharmacotherapies aimed at optimizing metabolic factors and reducing urinary supersaturation of stone components that play an important role in urinary stone prevention. In addition, medical expulsive therapy for ureteral stones and medical dissolution therapy for uric acid-based urinary stones are helpful treatment tools and are used alongside surgical treatments in the management of urinary stones.

The impact of stenting prior to oral chemolysis of upper urinary tract uric acid stones

PURPOSE

To evaluate the impact of ureteral stenting on the success rate of oral chemolysis in the management of suspected uric acid upper urinary tract (UUT) stones.

METHODS

Retrospective matched-pair analysis of 172 patients treated with oral chemolysis from 01/2010 to 12/2019. Patients with low density (upon non-contrast enhanced computer tomography [NCCT]), radiolucent (on plain radiography) urinary stones, a low urine pH (< 6) and/or history of uric acid urolithiasis were included. Potassium citrate and/or sodium bicarbonate were used for alkalization (target urine pH: 6.5-7.2). Patient 1:1 matching was performed for the presence of indwelling ureteral stent, stone diameter, stone density, and stone localization. Stone-free status was evaluated after 12 weeks using NCCT. Multivariable logistic regression analysis was used to assess factors affecting the outcome.

RESULTS

Mean patient age was 61 years (73% males). Mean stone size was 12 mm. Overall success rates after 12-weeks of chemolysis for stones at any localization in the UUT and ureteral stones were 60.5 and 77.3%, respectively. Smaller stone size (OR = 0.94; CI 0.888-0.992; p = 0.026) and lower pre-treatment urine pH (OR = 0.131; CI 0.023-0.737; p = 0.021) significantly increased the success of oral chemolysis. Ureteral stenting did not have any impact on the efficacy of oral chemolysis.

CONCLUSION

Oral chemolysis is an effective treatment modality for patients with UUT stones suspected of uric acid content irrespective of ureteral stenting. Smaller stone diameter and lower urine pH at diagnosis increase its efficacy.

Optimization of shockwave lithotripsy use for single medium sized hard renal stone with stone density ≥ 1000 HU. A prospective study

PURPOSE

To identify shock wave lithotripsy (SWL) success predictors in hard renal stones (average stone density ≥ 1000 HU).

MATERIALS

We prospectively evaluated patients who underwent SWL for hard renal stones between April 2018 and December 2020. Radiological parameters were identified, e.g., stone site, size, the average density in addition to stone core and shell mean density, and renal cortical thickness (RKT). SWL sessions were performed using Doli-S lithotripter till a maximum of 3-4 sessions with 2-4 weeks interval. Initial response to SWL included stone fragmentation and decreased stone size after the first SWL. Treatment success was considered if complete clearance of renal stones occurred or in case of clinically insignificant residual fragments ≤ 4 mm after 12 weeks follow up by NCCT.

RESULTS

Out of 1878 patients who underwent SWL, the study included 157 patients with hard renal stones. Treatment overall success was found in 92 patients (58.6%) where 69 patients (43.9%) had complete stone clearance. On multivariate analysis, stone shell density < 901 HU, maximum stone size < 1 cm, RKT > 1.95 cm and initial treatment response were associated with increased the success rate after SWL for hard renal stones (P = 0.0001, 0.009, < 0.0001 and < 0.0001, respectively).

CONCLUSION

In hard renal stones, treatment overall success was found in 58.6% where complete stone clearance was found in 43.9%. Stone outer shell fragility, lower stone size, increased RKT and initial response to SWL were associated with a higher success rate at 12-week follow-up.

Outcomes of dissolution therapy and monitoring for stone disease: should we do better?

PURPOSE OF REVIEW

Surgical management is the cornerstone of urolithiasis treatment, but high recurrence rates and associated complications necessitate the existence of medical treatment options, aiming at dissolution of kidney stones and prevention of recurrence. The purpose of this review is to present the most recent knowledge existing in scientific literature, regarding dissolution therapy and ways of monitoring nephrolithiasis patients.

RECENT FINDINGS

A number of laboratory studies have been performed testing experimental treatments (tolvaptan, chlorthalidone, atorvastatin, a-lipoic acid, glucosaminoglycans, plant extracts), to reduce kidney stone formation and cellular damage and showed encouraging results. Uric acid stones is the main target of dissolution therapy, but until last years, existing level of evidence was low. A number of prospective and randomized studies, proved the efficacy and safety of oral chemolysis for radiolucent stones and associated prognostic features of success. Tolvaptan and a-Lipoic acid were also tested in patients with cystinuria and resulted in reduction of recurrence. Finally, some new diagnostic markers are suggested as tests for the monitoring of urolithiasis patients, with satisfying accuracy and discriminative ability.

SUMMARY

Medical dissolution therapy for nephrolithiasis is an effective option, especially for patients with radiolucent/uric acid stones. In the future, we need clinical trials to confirm the encouraging results of pilot studies testing several agents for patients with cystinuria.

Is Percutaneous Nephrolithotomy the Modality of Choice Versus Extracorporeal Shockwave Lithotripsy for a 20 to 30 mm Single Renal Pelvic Stone with ≤1000 Hounsfield Unit in Adults? A Prospective Randomized Comparative Study

Objectives: To compare the efficacy, complications, and costs of percutaneous nephrolithotomy (PNL) and extracorporeal shock wave lithotripsy (SWL) in the treatment of a 20 to 30 mm single renal pelvic stone with a density ≤1000 HU. Patients and Methods: Eighty patients were prospectively randomized to receive either PNL or SWL during May 2017 to April 2019. The relevant demographic and clinical characteristics were compared. Results: The mean age in the PNL and SWL groups was 43.25 ± 15.16 and 44.18 ± 12.08 years, respectively. The mean stone sizes were 25.2 ± 3.9 and 24.6 ± 2.3 mm, respectively. The stone-free rate (SFR) was significantly different after the primary procedures (92.5% vs 37.5%, respectively; p < 0.04), but it was comparable after 3 months (97.5% vs 90%, respectively; p = 0.723), with a higher rate of auxiliary procedures after SWL (p = 0.017). On multivariate analysis, stone density was the only significant variable for the SFR in the SWL group (p = 0.004). Complications occurred in 27.5% and 22.5% of cases, respectively (p = 0.796). The mean costs of SWL (650.23 ± 424.74 United States Dollars [US$]) were significantly lower than those of PNL (1137.65 ± 224.43 US$; p < 0.0001). Conclusions: The SFRs for PNL and SWL were not significantly different after 3 months in the treatment of a 20 to 30 mm single renal pelvic stone with ≤1000 HU, although PNL provided a significantly higher rate after its primary procedure. SWL was significantly less costly, but it mandated a significantly higher number of auxiliary procedures than PNL.

Oral chemolysis is an effective, non-invasive therapy for urinary stones suspected of uric acid content

Despite the possible benefit from avoiding stone surgery with all its possible complications, oral chemolysis is rarely performed in patients with urinary stones suspected of uric acid content. Among the reasons for its limited use is the sparse and low-quality data on its efficacy and the lack of reliable factors predicting its outcome. We thus performed a retrospective single-center cohort study of 216 patients (median patient age 63 years) with 272 renal (48%) and/or ureteral (52%) stones treated with oral chemolysis from 01/2010 to 12/2019. Patients with low urine pH (< 6), low stone density upon non-contrast enhanced computed tomography (NCCT), radiolucent urinary stones on plain radiography, and/or a history of uric acid urolithiasis were included. Potassium citrate and/or sodium/magnesium bicarbonate were used for alkalization (target urine pH 6.5–7.2). Median stone size was 9 mm, median stone density 430 Hounsfield Units. Patients with ureteral stones < 6 mm were excluded since stones this small are very likely to pass spontaneously. The stone-free status of each patient was evaluated after 3 months using NCCT. Oral chemolysis was effective with a complete and partial response rate of stones at 3 months of 61% and 14%, respectively; 25% of stones could not be dissolved. Lower stone density (OR = 0.997 [CI 0.994–0.999]; p = 0.008) and smaller stone size (OR = 0.959 [CI 0.924–0.995]; p = 0.025) significantly increased the success rate of oral chemolysis in multivariate logistic regression analysis. More precise stone diagnostics to exclude non-uric-acid stones could further improve outcome.