Interpreting the results of chemical stone analysis in the era of modern stone analysis techniques

Metabolic Evaluation and Recurrence Prevention for Urinary Stone Patients: An EAU Guidelines Update

BACKGROUND AND OBJECTIVE

The aim of this review was to define patients who are at high risk of recurrence of urolithiasis, to delineate diagnostic and therapeutic algorithms for each type of stone, and to clarify general guidelines and recommendations for prevention of recurrence.

METHODS

A professional research librarian carried out literature searches for all sections of the urolithiasis guidelines, covering the timeframe between 1976 and June 2023.

KEY FINDINGS AND LIMITATIONS

For every patient with urolithiasis, an attempt should be made to analyse the stone. Patients should be given general instructions on how to prevent recurrence, including adequate fluid and calcium intake, and low consumption of sodium and protein. Identifying and correcting the causative factors is a cornerstone in preventing the recurrence of urolithiasis. Diagnostic and therapeutic algorithms by stone composition are available. Every patient should undergo baseline metabolic screening, while patients with calcium stones, who are at high risk of relapse and complications, should undergo extensive metabolic screening with two 24-h urine collections and should receive targeted therapy. Patients with uric acid, infection, or cystine stones are at high risk of relapse. All patients at high risk of recurrence should be closely monitored, especially those not complying with therapy in the long term.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Metabolic stone evaluation and patient follow-up are highly recommended to prevent urolithiasis recurrence.

PATIENT SUMMARY

We reviewed the evidence for proper evaluation of patients with urinary and stones and the treatment options for preventing stone recurrence. It is essential to determine the type of stone and to carry out specific blood and urine tests for planning the best treatment course for each patient.

2022 Recommendations of the AFU Lithiasis Committee: Epidemiology, stone analysis and composition

The incidence of urinary lithiasis is rising steadily in industrialized countries, and its prevalence in the general population of France is estimated at 10%. Renal colic accounts for 1-2% of emergency department consultations. At a time when the new LASER stone fragmentation techniques available to urologists will lead to ever finer in situ pulverization of stones, the exact identification of the compounds that form the stone is essential for etiological diagnosis. Constitutional analysis by infrared spectrophotometry or X-ray diffraction is therefore recommended, to be complemented by morphological typing of the calculi. METHODOLOGY: These recommendations have been drawn up using two methods: the Recommendation for Clinical Practice (RPC) method and the ADAPTE method, depending on whether or not the issue was considered in the EAU recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU 2022] and their adaptability to the French context.

Real-time and accurate calibration detection of gout stones based on terahertz and Raman spectroscopy

Gout is a metabolic disease that can result in the formation of gout stones. It is essential to promptly identify and confirm the type of gout stone to alleviate pain and inflammation in patients and prevent complications associated with gout stones. Traditional detection methods, such as X-ray, ultrasound, CT scanning, and blood uric acid measurement, have limitations in early diagnosis. Therefore, this article aims to explore the use of micro Raman spectroscopy, Fourier transform infrared spectroscopy, and Terahertz time-domain spectroscopy systems to detect gout stone samples. Through comparative analysis, Terahertz technology and Raman spectroscopy have been found to provide chemical composition and molecular structure information of different wavebands of samples. By combining these two technologies, faster and more comprehensive analysis and characterization of samples can be achieved. In the future, handheld portable integrated testing instruments will be developed to improve the efficiency and accuracy of testing. Furthermore, this article proposes establishing a spectral database of gout stones and urinary stones by combining Raman spectroscopy and Terahertz spectroscopy. This database would provide accurate and comprehensive technical support for the rapid diagnosis of gout in clinical practice.

Autofluorescence spectral analysis for detecting urinary stone composition in emulated intraoperative ambient

The prevalence and disease burden of urolithiasis has increased substantially worldwide in the last decade, and intraluminal holmium laser lithotripsy has become the primary treatment method. However, inappropriate laser energy settings increase the risk of perioperative complications, largely due to the lack of intraoperative information on the stone composition, which determines the stone melting point. To address this issue, we developed a fiber-based fluorescence spectrometry method that detects and classifies the autofluorescence spectral fingerprints of urinary stones into three categories: calcium oxalate, uric acid, and struvite. By applying the support vector machine (SVM), the prediction accuracy achieved 90.28 % and 96.70% for classifying calcium stones versus non-calcium stones and uric acid versus struvite, respectively. High accuracy and specificity were achieved for a wide range of working distances and angles between the fiber tip and stone surface in an emulated intraoperative ambient. Our work establishes the methodological basis for engineering a clinical device that achieves real-time, in situ classification of urinary stones for optimizing the laser ablation parameters and reducing perioperative complications in lithotripsy.

The relationship between patients' kidney stone type and demographics in Israel: analysis of 10 K patients

PURPOSE

To analyze urinary stone composition in Israel and assess the effects of key demographic parameters (gender, age, socioeconomic status, ethnicity, medical history and geographic region) on stone composition.

METHODS

A retrospective review was conducted of stone analysis of 10,633 patients from an HMO Israeli database analyzed by a central laboratory from 2014 to 2019 and subjected to Fourier-transform infrared spectroscopy. Associations between stone composition and different demographic parameters were determined using the Chi-square test.

RESULTS

Calcium oxalate (CaOx) monohydrate accounted for 51.9% of the stones. Of the total sample, 5776 stones had one single component (54%), whereas 4857 (46%) had mixed components. Men had a higher frequency of CaOx stones (89.6% vs. 85.6%), whereas women had a higher frequency of calcium phosphate, infection, and cystine stones (27.2%, 17.7%, and 0.9% vs. 17.2%, 7.5%, and 0.5%, respectively). Cystine stones were more abundant in Arabs (1.2% vs. 0.5% in the Jewish population). Lower socioeconomic status was associated with a higher prevalence of calcium phosphate, uric acid, and infection stones and a lower prevalence of CaOx stones. Uric acid stones were associated with medical conditions such as diabetes, hypertension, ischemic heart disease, and obesity (28.3%, 24.9%, 25.7%, and 22.6% vs. 9.6%, 8.4%, 12.3%, and 10.3%, respectively).

CONCLUSIONS

Stone types were highly influenced by patients' demographics. COM was the most common stone component in either pure or complex form. UA stone prevalence was found to increase with age and was associated with medical conditions such as diabetes, hypertension, ischemic heart disease, and obesity.

Attitudes of urologists on metabolic evaluation for urolithiasis: outcomes of a global survey from 57 countries

Although stone disease is an important health problem with high incidence and recurrence rates, it is a preventable disease. Attitudes and practices of urologists regarding the prevention of recurrence continue to be a subject of debate. In this context, an online survey study was conducted involving 305 urologists from 57 different countries. The first 7 questions collected demographic data about the urologists and the remaining 23 questions were about the recurrence and metabolic evaluation, medical treatment, and follow-up of urinary stone disease. Most urologists (85.2%) thought that metabolic examination was important. Approximately one-third of the participants (34.1%) performed 24-hour urine analysis and stone analysis was ordered by 87.5% of the urologists. Metabolic analysis was performed for all patients by 14.7% of the participants. For pediatric patients this rate was 68.5%, and for adults with recurrence the rate was 81.6%. Reasons cited by the urologists for not performing metabolic analysis included not feeling confident doing so (18.3%), having limited facilities in their hospital (26.5%), having an excessive daily workload (31.8%), patient-related factors (27.5%), and referring patients to other departments for metabolic evaluation (20.9%). Although majority of the responding urologists do consider the metabolic analysis as vital important, they seemed not to be willing to perform these tests with the same degree of enthusiasm in their daily practice. Our results show that urologists need support in performing and interpreting 24-hour urine analysis, improving their knowledge levels, and communicating with patients. Urology residency training should focus more on the prevention of urinary stone recurrence in addition to the surgical training.

Composition of Uroliths seen in patients in Abuja, Nigeria: a single centre retrospective analysis of 155 stones

Background

Uroliths are stones formed in the urinary tract. Analysis of stones helps to identify risk factors for their development and prevention of recurrence. Standard stone analysis using modern technology is not routinely done in Nigeria. This study sought to determine the chemical composition of urinary stones seen in Abuja, Nigeria.

Methods

This was a retrospective study on composition of uroliths. Urinary stones surgically removed from 155 patients through minimal access surgical procedures between January 2015 and August 2019 were analysed. Optical crystallography and infrared spectroscopy were used to determine the chemical composition of the urinary stones.

Results

A total of 155 urinary stones were assembled from the patients. More stones were removed from male patients and the male to female ratio was 1.9:1. Stones were rare in the extremes of age. The predominant location (89.7%) of stones was in the upper urinary tract. All stones were of mixed composition with calcium oxalate accounting for 93.55%. Calcium oxalate, calcium phosphate and uric acid stones were more common in the upper tract, while 2 of the 3 struvite stones were found in the lower tract.

Conclusion

Stones found in this study were of mixed composition with the most common constituent being Calcium oxalate and the least common, struvite.

Urine and stone analysis for the investigation of the renal stone former: a consensus conference

The Consensus Group deliberated on a number of questions concerning urine and stone analysis over a period of months, and then met to develop consensus. The Group concluded that analyses of urine and stones should be routine in the diagnosis and treatment of urinary stone diseases. At present, the 24-h urine is the most useful type of urine collection, and accepted methods for analysis are described. Patient education is also important for obtaining a proper urine sample. Graphical methods for reporting urine analysis results can be helpful both for the physician and for educating the patient as to proper dietary changes that could be beneficial. Proper analysis of stones is also essential for diagnosis and management of patients. The Consensus Group also agreed that research has shown that evaluation of urinary crystals could be very valuable, but the Group also recognizes that existing methods for assessment of crystalluria do not allow this to be part of stone treatment in many places.

The correlation between demographic factors and upper urinary tract stone composition in the Thai population

Objective

To identify the correlation between demographic factors and upper urinary tract stone composition in the Thai population.

Method

A retrospective observational study of first-time upper urinary tract stone former patients aged over 18 years who underwent stone surgery was performed in a tertiary referral university hospital from January 2013 to May 2018. Collected data included demographic information and stone composition information, which were analysed by the Fourier Transform-Infrared Spectroscopy (FTIR) method. The correlation between the demographic factors and major upper urinary tract stone composition was analysed using Fisher's exact test.

Results

A total of 480 patients were included in this study. The stones were 319 (66.5%) renal calculi and 161 (33.5%) ureteric calculi. There were 248 (51.7%) single composition stones and 232 (48.3%) mixed composition stones. The major stone compositions were 288 (60.0%) calcium oxalate (CaOx), 125 (26.0%) calcium phosphate (CaP), 40 (8.3%) uric acid (UA), 19 (4.0%) magnesium ammonium phosphate (MAP), five (1.0%) cystine, and three (0.6%) ammonium hydrogen urate (AHU). Gender was correlated with the major stone composition. In females, a correlation was found between the major stone composition and age, diabetes mellitus (DM), and glomerular filtration rate (GFR). The study showed no significant correlation between the major stone composition and dyslipidemia (DLP), hypertension (HT), gout, and body mass index (BMI) in both genders.

Conclusion

Gender, age, DM, and GFR were the factors affecting the stone composition.

Analysis of stones formed in the human gall bladder and kidney using advanced spectroscopic techniques

Stone diseases (gallstones and kidney stones) are extremely painful and often cause death. The prime aim of biomedical research in this area has been determination of factors resulting in stone formation inside the gallbladder and urinary tract. Many theories have been put forward to explain the mechanism of stone formation and their growth; however, their complete cycle of pathogenesis is still under debate. Several factors are responsible for stone formation; however, much emphasis is placed on the determination of elemental and molecular composition of the stones. In the present review article, we describe different kinds of spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF) spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and laser-induced breakdown spectroscopy (LIBS) and highlight their use in the analysis of stone diseases. We have summarized work done on gallstones and kidney stones using these advanced techniques particularly over the last 10 years. We have also briefly elaborated the basics of stone formations inside the human body and their complications for a better understanding of the subject.

Raman chemical imaging, a new tool in kidney stone structure analysis: Case-study and comparison to Fourier Transform Infrared spectroscopy

BACKGROUND AND OBJECTIVES

The kidney stone's structure might provide clinical information in addition to the stone composition. The Raman chemical imaging is a technology used for the production of two-dimension maps of the constituents' distribution in samples. We aimed at determining the use of Raman chemical imaging in urinary stone analysis.

MATERIAL AND METHODS

Fourteen calculi were analyzed by Raman chemical imaging using a confocal Raman microspectrophotometer. They were selected according to their heterogeneous composition and morphology. Raman chemical imaging was performed on the whole section of stones. Once acquired, the data were baseline corrected and analyzed by MCR-ALS. Results were then compared to the spectra obtained by Fourier Transform Infrared spectroscopy.

RESULTS

Raman chemical imaging succeeded in identifying almost all the chemical components of each sample, including monohydrate and dihydrate calcium oxalate, anhydrous and dihydrate uric acid, apatite, struvite, brushite, and rare chemicals like whitlockite, ammonium urate and drugs. However, proteins couldn't be detected because of the huge autofluorescence background and the small concentration of these poor Raman scatterers. Carbapatite and calcium oxalate were correctly detected even when they represented less than 5 percent of the whole stones. Moreover, Raman chemical imaging provided the distribution of components within the stones: nuclei were accurately identified, as well as thin layers of other components. Conversion of dihydrate to monohydrate calcium oxalate was correctly observed in the centre of one sample. The calcium oxalate monohydrate had different Raman spectra according to its localization.

CONCLUSION

Raman chemical imaging showed a good accuracy in comparison with infrared spectroscopy in identifying components of kidney stones. This analysis was also useful in determining the organization of components within stones, which help locating constituents in low quantity, such as nuclei. However, this analysis is time-consuming, making it more suitable for research studies rather than routine analysis.

Retrospective analysis of canine gallbladder contents in biliary sludge and gallbladder mucoceles

The pathophysiology of canine gallbladder diseases, including biliary sludge, gallbladder mucoceles and gallstones, is poorly understood. This study aimed to evaluate the component of gallbladder contents and bacterial infection of the gallbladder in order to elucidate the pathophysiology of biliary sludge and gallbladder mucoceles. A total of 43 samples of canine gallbladder contents (biliary sludge, 21 and gallbladder mucoceles, 22) were subjected to component analysis by infrared spectroscopy, and the resultant infrared spectra were compared with that of swine mucin. Of the 43 samples, 41 were also evaluated by aerobic and anaerobic bacterial culture. The contents of 20 (95.2%) biliary sludge and 22 (100%) gallbladder mucocele samples exhibited similar infrared spectra as swine mucin. Although biliary sludge and gallbladder mucocele contents exhibited similar infrared spectra, one sample of biliary sludge (4.8%) was determined to be composed of proteins. The rate of bacterial infection of the gallbladder was 10.0% for biliary sludge and 14.3% for gallbladder mucoceles. Almost all of the identified bacterial species were intestinal flora. These results indicate that the principal components of gallbladder contents in both gallbladder mucoceles and biliary sludge are mucins and that both pathophysiologies exhibit low rates of bacterial infection of the gallbladder. Therefore, it is possible that gallbladder mucoceles and biliary sludge have the same pathophysiology, and, rather than being independent diseases, they could possibly represent a continuous disease. Thus, biliary sludge could be considered as the stage preceding the appearance of gallbladder mucoceles.