Active Stone Formers Research Articles

MP05-04 ROLE OF CLINICALLY DERIVED URINARY SMALL MOLECULES IN LITHOGENESIS

You have accessJournal of UrologyCME1 Apr 2023MP05-04 ROLE OF CLINICALLY DERIVED URINARY SMALL MOLECULES IN LITHOGENESIS Jose Agudelo, Roxana Ramos, Smita De, and Aaron Miller Jose AgudeloJose Agudelo More articles by this author , Roxana RamosRoxana Ramos More articles by this author , Smita DeSmita De More articles by this author , and Aaron MillerAaron Miller More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003216.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Metabolomic characterization of the urine of active stone formers, healthy individuals, or non-active stone formers have revealed the presence of a set of differentially enriched biomolecules. We aimed to determine if these metabolites have a potential influence on lithogenesis with an in vitro approach. METHODS: A panel of 15 small molecules highlighted in previous studies that involved metabolomic characterization of urine specimens were purchased as lab grade chemicals. Eight of these were associated with stone activity, and seven with healthy or non-recurrent status. Four metrics of lithogenesis were assessed: crystal number, growth, aggregation, and crystal polymorphism. Assays were run in a basic Tris-HCL buffer at room temperature. 2-ml of 1 mM sodium oxalate and 2 ml of 10 mM calcium chloride were combined in 50mm Petri dish, with the addition of the target metabolite at 0 hours for crystallization, and at 60 minutes for crystal growth. Aggregation was assessed with the use of 1 μg of previously harvested crystals added to 4 ml of basic buffer, as a 1-hour reaction in a plate shaker at low speed. Samples were imaged with an inverted microscope and compared to a negative control. Results were quantified and compared with one-way Anova and post hoc t-tests. RESULTS: Effect of the metabolites on crystal metrics are presented in Figures 1 and 2. We observed a clear relationship between the lithogenesis metrics and the presence of the metabolites. Results indicate that the small molecules influence lithogenesis at the molecular level, or crystal development. At the supramolecular or crystal level, stone-associated metabolites increased calcium oxalate aggregation, while healthy-associated metabolites inhibited aggregation and altered crystal morphology. CONCLUSIONS: Our findings provide in vitro evidence of the effects of urinary small molecules derived from patients with urinary stones and healthy counterparts, with clear effects at the crystal level. Source of Funding: UCF Research Scholar Award/Lerner Research Institute © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e44 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jose Agudelo More articles by this author Roxana Ramos More articles by this author Smita De More articles by this author Aaron Miller More articles by this author Expand All Advertisement PDF downloadLoading ...

Difficulties in the surgical treatment of patients with cystinuria – a case report

Cystinuria is an autosomal recessive disorder. Two genes responsible for cystinuria have been identified: SLC3A1 (chromosome 2p21) and SL7A9 (chromosome 19q12). Their mutations cause high clinical variability in the course of the disorder. Over the past 10 years, an increase in the prevalence of cystinuria has been observed, which is now approximately 1:7,000 newborns. Similarly to cystic fibrosis, it is one of the most common diseases with this pattern of inheritance. Its clinical picture usually includes active stone formation (at least twice a year) and short periods of remission. Cystinuria relatively quickly leads to chronic renal failure. Patients with this disorder require constant supervision as well as monitoring of treatment outcomes. This paper presents a case of a 17-year-old boy diagnosed with cystinuria at the age of 3 months, when first bilateral pelvicalyceal stones were found on ultrasound. Immediately after the diagnosis, fluid supply was increased, treatment with captopril and a mixture of citrates (Shohl’s solution) was initiated, which in later years was switched to potassium citrate/tiopronin. The implemented conservative treatment and constant nephrological care failed to prevent relapses in the patient. The boy underwent a total of 40 surgical interventions, including minimally invasive endoscopic procedures (extracorporeal lithotripsy, percutaneous nephrolithotripsy, ureteroscopic lithotripsy, retrograde intrarenal surgery) and three open surgeries to completely remove kidney stones.

Delineating the Role of the Urinary Metabolome in the Lithogenesis of Calcium-Based Kidney Stones

ObjectiveTo delineate the role of the urinary metabolome in the genesis of urinary stone disease (USD). MethodsUntargeted metabolomics was utilized in comparative analyses of calcium-based stones (CBS) and spot urine samples from patients with a history of USD with or without urinary stone activity based on radiologic imaging. Stone and urine metabolomes were stratified by composition and radiographic stone-activity, respectively. Additionally, we quantified highly abundant metabolites that were present in either calcium oxalate (CaOx) or calcium phosphate (CaPhos) stones and also significantly enriched in the urine of active stone formers (SF) compared to non-active SF. These data were used to delineate either a direct involvement of urinary metabolites in lithogenesis or the passive uptake of biomolecules within the stone matrix. ResultsUrinary metabolomes were distinct based on radiographic stone-activity and the 2 types of CBS. Stratification by radiologic stone activity was driven by the enrichment of 14 metabolites in the urine of active SF that were also highly abundant in both CaOx and CaPhos stones, indicative of a potential involvement of these metabolites in lithogenesis. Using the combination of these 14 metabolites in total, we generated a model that correctly classified patients as either active vs non-active SF in a prospectively recruited cohort with 73% success. ConclusionCollectively, our data suggest specific urinary metabolites directly contribute to the formation of urinary stones and that active SF may excrete higher levels of lithogenic metabolites than non-active patients. Future studies are needed to confirm these findings and establish the causative mechanisms associated with these metabolites.

Systematic assessment of urinary hydroxy-oxo-glutarate for diagnosis and follow-up of primary hyperoxaluria type III.

There are currently three distinct autosomal recessive inherited types of primary hyperoxaluria (PH: PHI, PHII, and PHIII), all characterized by the endogenous overproduction of oxalate. The PH type is difficult to differentiate by clinical features alone. In addition to universal general characteristics to all hyperoxaluria subtypes, specific urinary metabolites can be detected: glycolate in PHI, L-glyceric acid in PHII, and hydroxy-oxo-glutarate (HOG) in PHIII. PHIII is considered to be the most benign form and is characterized by severe recurrent urolithiasis in early life, followed by clinical remission in many, but not all patients. We examined urinary HOG (UHOG) excretion as a diagnostic marker and its correlation to progression of the clinical course of PHIII. UHOG was analyzed by combined ion chromatography/mass spectrometry (IC/MS) in urine samples from 30 PHIII and 68 PHI/II patients and 79 non-PH hyperoxaluria patients. Mean UHOG excretion was significantly higher in patients with PHIII than in those with PHI/II and in non-PH patients(51.6 vs. 6.61 vs. 8.36 μmol/1.73 m2/24 h, respectively; p<0.01). Significantly elevated UHOG excretion was exclusively seen in PHIII patients and showed a 100 % consensus with the results of hydroxy-oxo-glutarate aldolase (HOGA1) mutational analysis in newly diagnosed patients. However, UHOG excretion did not correlate with clinical course on follow-up and could not be used to discriminate between active stone formers and patients with a clinically uneventful follow-up.

Effect of Medical Management on Recurrent Stone Formation Following Percutaneous Nephrolithotomy

Percutaneous nephrolithotomy is a commonly used procedure for treatment of large or complex renal calculi. In some instances postoperative residual stone fragments are an unavoidable result. Yet to our knowledge no study has examined the impact of medical management on stone formation in patients with or without residual fragments following percutaneous nephrolithotomy. Thus, we have conducted the first investigation of aggressive medical management following percutaneous nephrolithotomy and its impact on stone formation rates in patients with and without residual fragments. A total of 70 patients who underwent percutaneous nephrolithotomy and received counseling regarding selective medical management following a comprehensive metabolic evaluation, were identified. Patients were placed into 4 groups following percutaneous nephrolithotomy, that is stone-free or residual fragments, who underwent or did not undergo medical therapy. New stone formation was assessed by spontaneous stone passage in the absence of residual stone fragments, stone passage without change in the number of residual fragments, surgical removal of newly formed stones, or appearance of new stones or increase in size of stone or fragments on abdominal radiographs. Stone remission rates were also calculated. Selective medical therapy significantly decreased stone formation rates in the stone-free (0.67 stones per patient per year vs 0.02) and residual fragment groups (0.67 stones per patient per year vs 0.02) as determined by the Wilcoxon signed rank test (p<0.0001). Moreover, remission was observed in a higher proportion of patients in the medically treated stone-free and residual fragment groups (87% and 77%) when compared to the same groups without medical therapy (29% and 21%, chi-square test p<0.0001). Our findings suggest that comprehensive metabolic evaluation and aggressive medical management can control active stone formation and growth in patients with or without residual stone fragments after percutaneous nephrolithotomy. Given the inherent morbidity and increased costs attendant with repeat procedures, medical management should be instituted in patients following percutaneous nephrolithotomy without regard to stone-free status.

Risk factors determining active urinary stone formation in patients with urolithiasis

The goal of clinical and metabolic evaluation of patients with urinary stones is to identify patients at high risk for recurrent stone formation and as such, to allow the practitioner to suggest preventive therapies. However, knowledge about risk factors for active stone formation in patients with urolithiasis is limited. This study was initiated to assess the significance of several metabolic and clinical parameters for the determination of the risk of active stone formation. Study in 320 consecutive outpatients referred to our clinic for metabolic analysis. Clinical and metabolic parameters were determined by standardized procedures of questionnaires, serum biochemical profiles and urinalysis. In 21.5% of 284 patients with complete data stone formation was active. Hypercalciuria, hypocitraturia and urinary tract infections had odds ratios for active stone formation above 2.5, whereas the odds ratio of a positive family history was 0.38. Hyperuricosuria, hyperoxaluria and a low urinary volume did not influence the risk for active stone formation. The risk profile for active stone formation differs from the risk profile for urolithiasis in general. Metabolic evaluation and determination of those risk factors in patients with urolithiasis might improve the estimation of the risk of future stone formation.

Expression of proteins that inhibit calcium oxalate crystallization in vitro in the urine of normal and stone-forming individuals

The factors precipitating clinically active calcium oxalate (CaOx) urolithiasis are not known. This study examined the relationships between urinary proteins that inhibit CaOx crystallization in vitro and the incidence of CaOx urolithiasis. The first hypothesis is that levels of urinary CaOx crystallization inhibitors differ between clinically active stone formers (SFs) and normal individuals. The second hypothesis is that lower levels of urinary CaOx crystallization inhibitors contribute to the two- to threefold greater incidence of CaOx urolithiasis in males compared with females. These hypotheses were derived from previous observations on the expression of urinary inter-alpha-trypsin inhibitor trimer (IalphaTI-trimer) in normal and stone-forming individuals. The proteins of void urine samples from normal volunteers (24 males, 19 females) and CaOx-SFs (26 males, 16 females) were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoreactive IalphaTI-trimer, osteopontin, and prothrombin were detected by immunoblot plus enhanced chemiluminescence; the relative densities of the bands were then determined. With the exception of IalphaTI-trimer (P: </= 0.026, approximately twofold), there was no difference in the relative densities of CaOx crystallization inhibitors in the urine of normal and CaOx stone-forming individuals. Thus, there does not appear to be a generalized increase or decrease in levels of CaOx crystallization inhibitory proteins between normal and CaOx stone-forming individuals. The relative density of IalphaTI-trimer was approximately threefold greater in females than in males (P: </= 0.001). Differences in the relative densities of the other CaOx crystallization inhibitors were small and of questionable physiological importance. These data do not support the hypothesis that males have a greater incidence of CaOx urolithiasis because of a generalized decrease in urinary CaOx crystallization inhibitory protein levels.

DIFFERENTIAL EXPRESSION OF URINARY INTER-alpha-TRYPSIN INHIBITOR TRIMERS AND DIMERS IN NORMAL COMPARED TO ACTIVE CALCIUM OXALATE STONE FORMING MEN

Purpose We determine if the immunoreactive profile of urinary inter-alpha-trypsin inhibitor can be used to distinguish between normal individuals and individuals with calcium oxalate stone disease. Materials and Methods Urinary proteins were dialyzed against water (15 kDa. molecular weight cutoff), lyophilized and resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (6% acrylamide, reducing conditions) followed by Western blot. Inter-alpha-trypsin immunoreactive proteins were detected by enhanced chemiluminescence. Stone formation was confirmed to be active radiologically or passed as stone or gravel within 12 months of the sample. Stone composition was confirmed crystallographically. Normal individuals had no personal or familial history of urolithiasis and matched stone forming patients regarding race (white) and age (23 to 71 years old). Urine from a total of 101 individuals was analyzed. Results The intact inter-alpha-trypsin trimer ([approximately] 220 to 240 kDa.) and heavy chain (HC) 2-bikunin/HC1-bikunin dimers ([approximately] 115 to 130 kDa.) were detected more often in stone forming men (23 of 26 [89%] and 26 of 26 [100%], respectively) than in normal individuals (6 of 26 [23%] and 5 of 26 [19%], respectively, p < 0.0001). In those normal individuals who expressed inter-alpha-trypsin trimer and HC-bikunins the relative intensities were 5.3 +/− 1.4% and 16.3 +/− 17.1% of the stone forming controls, respectively. The identity of high molecular weight-inter-alpha-trypsin immunoreactive bands was confirmed using antibodies against the individual subunits (HC1, HC2, HC3, bikunin). In contrast to men high molecular weight-inter-alpha-trypsin's were readily detected in normal and stone forming women with equal frequency (inter-alpha-trypsin-trimer p = 0.1337, HC-bikunins p = 0.2836): inter-alpha-trypsin-trimer 17 of 18 [94%] and 9 of 13 [77%]; HC-bikunins 17 of 18 [94%] and 10 of 13 [85%]). Inter-alpha-trypsin-trimer and HC-bikunins, respectively, were detected in 2 and 5 of 10 patients with chronic renal disease. Expression was not related to hematuria or proteinuria. Conclusions Immunoreactive profiles of urinary proteins may be able to be developed into a useful diagnostic tool to identify active stone formation, although a separate panel may be required for men and women. It is possible that these differences may provide clues as to why the incidence of stone disease is higher in men than women.

Genetic versus environmental factors in renal stone disease.

The dietary habits of renal stone formers appear to differ from those of the general population. Renal stone formers seem to eat more oxalate, more flesh protein and less vegetable fibres than their normal counterparts. Often their urine volume is low. These are environmental factors which govern nephrolithiasis. Subtle underlying defects are detected not infrequently in these patients; for example, medullary sponge kidneys, abnormally structured macromolecular inhibitors of calcium oxalate crystallization (nephrocalcin and Tamm-Horsfall protein), incomplete distal renal tubular acidosis, deficient activation of pyridoxine, defective intestinal absorption of citrate, excessive production of interleukin-1 by monocytes, subtle primary hyperparathyroidism, heterozygosity for cystinuria, and, discovered more recently, abnormal chloride channels along the nephron. Many of these defects are inheritable, but carriers of the trait are not always active stone formers. The opinion forwarded in this review is that combinations of the environmental and of the underlying or genetic defects are required to trigger renal stone disease.

Normal calcium oxalate crystal growth inhibition in severe calcium oxalate nephrolithiasis.

Urine from mammalian kidneys is regularly supersaturated with respect to calcium oxalate monohydrate, the most common solid phase in human nephrolithiasis, and also inhibits the nucleation, growth, and aggregation of calcium oxalate crystals. Nephrolithiasis is often associated with increased supersaturation, and it is assumed that this increase overbalances the inhibition effects, causing stones. However, some patients form stones in the absence of increased supersaturation, and in those patients, one might assume that reduced inhibition is the cause of their stones. This hypothesis was tested in 25 patients who formed at least ten stones each, yet lacked the usual metabolic abnormalities that increase supersaturation. Compared with 25 age- and sex-matched control subjects, urine supersaturation among the patients was not increased; this is an expected result of this study's selection criteria. Compared with the same age- and sex-matched control subjects, urine from the patients showed no evidence for reduced inhibition of calcium oxalate crystal growth, so low inhibition of growth did not contribute to pathogenesis of stones in our highly selected study population, despite their otherwise unexplained and active stone formation. These results do not support the hypothesis that growth inhibition defects are a cause of stone disease.

Prevention of calcium nephrolithiasis with low-dose thiazide, amiloride and allopurinol

We report 5 years' experience with low-dose hydrochlorothiazide, 50 mg/day and amiloride, 5 mg/day, in 519 patients with recurrent calcium nephrolithiasis. Additional treatment with allopurinol, 100 mg/day, was prescribed for approximately 50 percent of the patients. All patients had active stone formation, having 3,464 stones in 3,126 patient-years (6.67 stones per patient, 1.10 stones per year). Hypercalciuria was present in 65 percent of the patients and hyperuricosuria in 24 percent. The administration of low-dose hydrochlorothiazide was effective in reducing urinary calcium excretion in most patients. It is possible that the hypocalciuric effect of hydrochlorothiazide were enhanced by amiloride, an agent which has been shown to cause hypocalciuria when given alone. Significant side effects requiring discontinuation of the drug were observed in only 5 percent of the patients. During 872.8 patient-years of treatment, only 53 new stones were formed (0.10 stones per patient, 0.06 stones per year) in contrast with the 916 predicted ones. The difference (chi-square) is statistically significant (p < 0.001). These results show that the administration of low-dose hydrochlorothiazide and amiloride, either alone or in association with allopurinol, is clinically effective in reducing the rate of recurrence of calcium nephrolithiasis.