Calcium Oxalate Stone Patients Research Articles

Metabolic Profile of Calcium Oxalate Stone Patients with Enteric Hyperoxaluria and Impact of Dietary Intervention.

This study investigated the risk profile and the impact of dietary intervention in calcium oxalate stone formers with enteric hyperoxaluria under controlled, standardized conditions. Thirty-seven patients were included in the study. Dietary and 24-h urinary parameters were obtained on the self-selected diet and a balanced, standardized diet. Tests for [13C2]oxalate absorption, calcium- and ammonium chloride-loading were performed. Mean [13C2]oxalate absorption was 18.8%. A significant positive association was observed between urinary oxalate excretion and intestinal oxalate absorption. In addition, urinary oxalate excretion was significantly correlated with dietary oxalate intake. Mean urinary oxalate excretion decreased from 0.841 mmol/24 h on the usual diet to 0.662 mmol/24 h on the balanced diet, corresponding to a reduction of 21.3%. Besides hyperoxaluria, hypocitraturia and hypomagnesuria were the most common urinary abnormalities at baseline, being present in 83.8% and 81.1% of patients, respectively. Urinary citrate increased by 50.9% and magnesium excretion increased by 25.2% on the balanced diet. As a result, the relative supersaturation of calcium oxalate declined significantly (by 36.2%) on the balanced diet. Since 41% of patients on the balanced diet still had a urine volume of less than 2.0 L/24 h, efforts should be made to increase urine volume by increasing fluid intake and reducing intestinal fluid losses. Dietary intervention proved to be effective in reducing urinary oxalate excretion and should be a cornerstone of the treatment of patients with enteric hyperoxaluria.

The urinary microbiota composition and functionality of calcium oxalate stone formers.

Accumulated evidences indicate that dysbiosis of the urinary microbiota is associated with kidney stone formation. In the present study, we aimed to investigate the urinary microbiota composition and functionality of patients with calcium oxalate stones and compare it with those of healthy individuals. We collected bladder urine samples from 68 adult patients with calcium oxalate stones and 54 age-matched healthy controls by transurethral catheterization. 16S rRNA gene and shotgun sequencing were utilized to characterize the urinary microbiota and functionality associated with calcium oxalate stones. After further exclusion, a total of 100 subjects was finally included and analyzed. The diversity of the urinary microbiota in calcium oxalate stone patients was not significantly different from that of healthy controls. However, the urinary microbiota structure of calcium oxalate stone formers significantly differed from that of healthy controls (PERMANOVA, r = 0.026, P = 0.019). Differential representation of bacteria (e.g., Bifidobacterium) and several enriched functional pathways (e.g., threonine biosynthesis) were identified in the urine of calcium oxalate stone patients. Our results showed significantly different urinary microbiota structure and several enriched functional pathways in calcium oxalate stone patients, which provide new insight into the pathogenesis of calcium oxalate stones.

Patient compliance for metabolic evaluation and medical treatment (CoMET) in calcium-oxalate stone patients: prospective study by EULIS eCORE study group.

In this study, we aimed to identify the compliance rates of calcium-oxalate stone patients for metabolic evaluation, diet and medical treatment and also determine the factors that are associated with poor compliance rates. This study was conducted by the EULIS eCORE working group prospectively. In the initial visit, demographic and stone-related characteristics were recorded. Patients were suggested metabolic evaluation, dietary advices and medical treatment. Follow-up visit was performed after 3months and compliance rates were recorded. Logistic regression analysis was performed to determine factors associated with poor compliance to metabolic evaluation, diet and medical treatment. Data of 346 patients from nine centers were analyzed. Compliance rates were 71.7%, 65.3%, and 63.7% for metabolic evaluation, diet, and medical treatment, respectively. In multivariate analysis, level of education (p = 0.003), history of emergency department visit (p = 0.04), number of stone surgeries (p = 0.03), patient care in dedicated stone clinic (p = 0.03), and history of shock wave lithotripsy (p = 0.005) were detected as independent predictors of compliance to metabolic analysis. Level of education (p < 0.001) and history of emergency department visit (p = 0.01) were detected as independent predictors of patient compliance to diet. Number of stone episodes (p = 0.03), family history of stones (p = 0.02), and polypharmacy (p < 0.001) were detected as independent predictors of patient compliance to medical treatment. Patient compliance to metabolic evaluation, diet, and medical therapy is important for successful management of urolithiasis. Dietary advices and medications should be personalized by taking in to account the factors associated with poor compliance.

Effect of Copper and Zinc Ions on Biochemical and Molecular Characteristics of Calcium Oxalate Renal Stones: a Controlled Clinical Study.

Contradictory results are existed in the literature regarding the impact of trace elements on the pathogenesis of calcium oxalate (CaOx) stone patients. Therefore, the aim of our study was to investigate the effect of Cu and Zn on biochemical and molecular characteristics of CaOx stones. Plasma and urine concentrations of Cu and Zn in 30 CaOx stones patients and 20 controls were determined by flame atomic absorption spectrometry (FAAS). Urinary levels of citric acid and oxalate were measured by commercial spectrophotometric kits. Blood levels of glutathione reduced (GSH) and catalase (CAT) were determined as markers of antioxidant activity, while blood malondialdehyde (MDA) and urine level of nitric oxide (NO) were used to assess oxidative stress. Gene expression of MAPk pathway (ERK, P38, and JNK) were estimated. The plasma and urine levels of Cu were significantly increased in the patient group compared to those of controls, while the levels of Zn were decreased. Excessive urinary excretion of citric acid and oxalate were found among CaOx stone patients. The GSH and CAT concentration were significantly reduced in CaOx stones patients compared to healthy group. The plasma MDA and urine NO concentration were significantly increased in CaOx stones patients compared to control group. The expressions of the studied genes were significantly increased in CaOx stones patients. These findings suggest that alteration in Cu and Zn might contribute to pathogenesis of CaOx patients through oxidative stress and MAPK pathway genes (ERK, P38 and JNK).

Three-fluorescence sensor for minute-time scale low-cost analysis of urinary oxalate in urolithiasis metabolic assessment

Since oxalate plays an important role in the metabolic assessment of urolithiasis, there is need for convenient and efficient methods for oxalate detection. Herein, we report a three-signal fluorescence strategy for oxalate analysis based on the ability of oxalate to reduce Cu2+ to Cu+, and the ability of pyrophosphate-cerium coordination polymeric networks (PPi-Ce CPNs), cadmium telluride quantum dots (CdTe QDs), and N-Methyl Mesoporphyrin (NMM) to selectively detect Cu2+ and Cu+. The detection range was 100 nM to 1 mM, the turnaround time was 6 min, while the limits of detections for PPi-Ce CPNs, QDs and NMM as reporters were 25 nM, 10 nM and 40 nM, respectively. Visual detection of oxalate relied on color change in the solution, which could be observed using the naked eye. The fluorescent system was used for oxalate analysis in 44 urine samples (32 calcium oxalate stone patients, 12 controls without urolithiasis), and the results were consistent with clinical diagnosis and imaging data. Moreover, the visual system was used to analyze 8 urine samples (4 patients and 4 controls), and showed good consistency with clinical diagnosis and computed tomography imaging results. These findings suggest that the method has potential application for the metabolic assessment of urolithiasis.

The Preliminary Exploration of What Role miRNAs Derived From Urinary Exosomes Play in Kidney Stone Formation

To identify dysregulated microRNAs (miRNAs) derived from urinary small Extracellular Vesicles (sEVs) and to explore the potential roles sEVs miRNAs play in nephrolithiasis. First morning voids were collected from participants. Urinary exosomes were isolated via sequential differential centrifugation and ultracentrifugation. Next-generation sequencing was conducted to analyze the transcriptome of urine sEVs from three Calcium oxalate (CaOx) stone patients and three age-/sex-matched healthy controls. Bioinformatics analysis was performed to explore how dysregulated miRNAs were associated with stone formation. The miRNA sequencing results of sEVs derived from epithelial cells (GSE110509) were compared with the dysregulated miRNAs of our study, and finally we found three common miRNAs. 54 dysregulated miRNAs were found between control and stone groups, among which 14 miRNAs were down-regulated and 40 miRNAs were up-regulated in stone groups compared to control groups. Gene ontology (GO) analysis indicated that dysregulated miRNAs were enriched in oxidative stress (Biological Process), focal adhesion (Cellular Component), and cell adhesion molecule binding (Molecular Function). Kyoto Encyclopedia of Genes and Genomes pathways analysis demonstrated that dysregulated miRNAs were common enriched in MAPK signaling pathway, focal adhesion and AGE-RAGE signaling pathway. The expression of miR-223-3p, miR-127-3p, and miR-214-5p were significantly different in either the sEVs derived from cells (GSE110509) or the sEVs derived from urine. QPCR confirmed that the expression of miR-223-3p was higher in urinary sEVs derived from CaOx stone patients. The expression of miR-223-3p is significantly higher in urinary sEVs derived from CaOx stone patients and may affect stone formation via regulating oxidative stress, focal adhesion and inflammation process.

Association of Gut Microbiota and Biochemical Features in a Chinese Population With Renal Uric Acid Stone.

Previous studies suggest that patients with nephrolithiasis exhibit dysbiosis in their gut microbiota, but those studies were conducted in calcium oxalate stone patients. We aimed to explore the association of gut microbiota and biochemical features of renal uric acid stone (UAS) patients in a Chinese population and identify the related bacteria that may affect the pathopoiesis of UAS. A case-control study of 117 patients with UAS, 123 patients with gout, and 135 healthy controls were included from January 2014 to October 2020. For each subject, data on demographics, biochemical parameters of blood and urine were analyzed. Fifteen patients with gout, 16 patients with UAS, 17 UAS patients with gout, and 17 healthy subjects were enrolled and provided fecal samples. The characteristics of gut microbiota were explored by using 16S ribosomal RNA (rRNA) gene sequencing and analyzed by using a combination of software mother and R. Hyperuricemia was the main risk factor for the development of gout and UAS. Obesity, dyslipidemia, and aciduria were unique risk factors for UAS patients. The richness, diversity, and relative abundance of dominant bacteria at the phylum and genus levels of gut microbiota in UAS patients were significantly distinct from other subjects. Abundance of Bacteroides and Fusobacterium was significantly positively correlated with the serum uric acid (UA) level of UAS patients. Fusobacteria was involved in the metabolism and degradation of certain short-chain fatty acids, amino acids, and sugars in pathopoiesis of UAS, and inhibited their synthesis pathways. Fusobacteria may be related to the pathogenesis of UAS, and this finding contributes to the personalized treatment of UAS from the perspective of maintaining micro-ecological equilibrium in gut.

852 - Whole genome analysis and phylogenetic characteristics of Escherichia coli isolated from urine and stones in calcium oxalate stone patients

852 - Whole genome analysis and phylogenetic characteristics of Escherichia coli isolated from urine and stones in calcium oxalate stone patients

MP03-10 WHOLE GENOME ANALYSIS AND PHYLOGENETIC CHARACTERISTICS OF ESCHERICHIA COLI ISOLATED FROM URINE AND STONES IN CALCIUM OXALATE STONE PATIENTS

INTRODUCTION AND OBJECTIVE:Escherichia coli (E. coli) was the most common bacteria isolated both from urine and stones in calcium oxalate (CaOx) stone patients. However, the differences between E. ...

Helper T-cell signaling and inflammatory pathway lead to formation of calcium phosphate but not calcium oxalate stones on Randall's plaques.

To elucidate the difference in the lithogenesis of calcium oxalate and calcium phosphate stones. Renal papillary tissues were obtained from 23 idiopathic calcium oxalate and seven calcium phosphate stone patients who had undergone endoscopic lithotripsy. Samples were individually collected from two different regions in each patient: the papillary mucosa containing Randall's plaque and mucosa not containing Randall's plaque. A microarray analysis was carried out on those tissues to compare their gene expression patterns. Furthermore, a causal pathway analysis comparing their differences was carried out. Cluster analysis showed that gene expression profiles of calcium phosphate stone patients markedly differed from those of calcium oxalate stone patients. Disease and function analysis showed that Randall's plaque-containing tissues of calcium phosphate stone-forming patients had significantly higher movement and migration of mononuclear leukocytes, and lower tendency toward infection and lymph node formation than Randall's plaque-containing tissues of calcium oxalate stone formers. Additional pathway analysis showed increased immune cell signaling in calcium phosphate formers, such as the helper Tcell 1 and 2 pathways, which was confirmed by their messenger ribonucleic acid expression. The present results show the upregulation of helper T-cell signaling pathways in Randall's plaque-containing papillae in calcium phosphate, but not in calcium oxalate stone formers. Thus, helper T-cell immune responses and the related inflammatory processes seem to lead to the formation of calcium phosphate stones on Randall's plaques.

Rs11567842 SNP in SLC13A2 gene associates with hypocitraturia in Thai patients with nephrolithiasis.

Hypocitraturia is a profound risk for kidney stone formation and recurrence. Sodium-dicarboxylate cotransporter-1 (NaDC-1) is a main transporter responsible for citrate reabsorption in renal proximal tubules. To investigate an association of sodium-dicarboxylate cotransporter-1 (NaDC-1) polymorphism with hypocitraturia in Thai patients with nephrolithiasis (NL). Exonic SNPs in NaDC-1 were screened in peripheral blood DNA of 13 NL patients. The rs11567842 (A/G) variant was found and further genotyped in 145 NL patients and 115 non-stone forming controls. NL patients had significantly lower level of urinary citrate than the controls. Based on logistic regression, hypocitraturia was significantly associated with urinary stone formation (adjusted OR 8.34, 95% CI 4.63-15.04). Significant association of urinary citrate level with rs11567842 genotype was found only in the NL group. NL patients with GG genotype had significantly higher urinary citrate than those with AA and AG genotypes. GG carrying patients had significantly reduced risk for hypocitraturia (adjusted OR 0.15; 95% CI 0.05-0.48, AA as reference). In selected 15 calcium oxalate stone patients, AA carriers had significantly higher intrarenal NaDC-1 mRNA than GG and AG carriers. Homozygous GG of rs11567842 SNP in NaDC-1 gene was a protective genotype for hypocitraturia in kidney stone patients. The findings suggested that patients with AA genotypes were more susceptible to hypocitraturia than those with GG, hence carrying a higher risk for kidney stone recurrence.

Metabolic assessment of recurrent and first renal calcium oxalate stone formers.

This study aimed to demonstrate the dominant role of metabolic disorders in the formation of calcium oxalate stones in patients with recurrent urolithiasis, as well as in patients experiencing their first episode of urolithiasis. The records of the patients who attended our kidney stone outpatient clinics between 2008 and 2012 were reviewed, and the data of 318 calcium oxalate stone patients who had undergone a metabolic assessment were retrospectively analysed. The patients were divided in two groups. The first group included the patients who presented with their first episode of urolithiasis (Group 1, n = 170), and the second group included patients with recurrent urolithiasis (Group 2, n = 148); intergroup comparisons of metabolic disorders were performed. A significant difference was found between the two groups in mean urine calcium levels (Group 1, 0.25; Group 2, 0.31; p = 0.001); the mean serum calcium level was found to be significantly higher although at less extent in Group 2 (Group 1, 9.4; Group 2, 9.6); p = 0.04). Significant differences were also found in mean urine citrate (Group 1, 481.9; Group 2, 397.2, p &lt; 0.0001) and oxalate levels (Group 1, 22.1; Group 2, 28.5; p &lt; 0.0001) . This study revealed a metabolic tendency to hypercalciuria in calcium oxalate stone patients, predominantly in those with recurrent calcium oxalate urolithiasis. Urinary oxalate excretion was found to be higher in recurrent urolithiasis in comparison to the first episode of calcium oxalate urolithiasis and urinary citrate excretion lower in recurrent urolithiasis.

Comparison of Physicochemical Properties of Nano‐ and Microsized Crystals in the Urine of Calcium Oxalate Stone Patients and Control Subjects

Purpose. To compare the properties of different sizes of urinary crystallites between calcium oxalate (CaOx) calculi patients and healthy controls. Methods. We studied the average particle size, size distribution, intensity‐autocorrelation curve, zeta potential (ζ), conductivity, mobility, aggregation state, and stability of different sizes of urinary crystallites by nanoparticle size analysis and transmission electron microscopy after filtration through a microporous membrane with an aperture size from 0.22 μm to 0.45, 1.2, 3, and 10 μm. Results. The urinary crystallites of the CaOx calculi patients were uneven and much easy to aggregate than those of controls. The number of large‐sized crystallites of the patients was significantly more than that of the controls. The main components of the nanosized urinary crystallites in patients were CaOx monohydrate (COM), uric acid, and β‐calcium phosphate, and these components were basically similar to those of the microsized urinary crystallites. The urinary crystallites of the calculi patients were easier to aggregate than that of the controls, and the small‐sized urinary crystallites were much easier to agglomerate. Conclusions. The urinary system of CaOx calculi patients is unstable and highly susceptible to urinary crystallite aggregation. The rapid aggregation of urinary crystallites may be the key factor affecting urolithiasis formation.

Chronic Stress and Calcium Oxalate Stone Disease: Influence on Blood Cortisol and Urine Composition

To evaluate the influence of chronic stress (CS) on urine composition of calcium oxalate (CaOx) stone patients and controls. This case-control study enrolled 128 patients during a period of 20 months. The cases were CaOx stone formers with a recent stone episode. Controls were matched by sex and age. Dimensions of CS were evaluated in cases and controls by validated self-report questionnaires measuring stressful life events, perceived stress, anxiety, depression, burnout, and satisfaction with life. Blood and urine samples were collected to determine cortisol levels and urinary composition. More relations between CS dimensions and blood and urine parameters were observed in cases than in controls. In cases, the blood cortisol level was related positively with the number of stressful life events (P = .03), intensity of these events (P = .04), and anxiety (P = .04). In addition, urinary magnesium (P = .03) and pyrophosphate (P = .05) levels were positively related with satisfaction with life and burnout, respectively. In contrast, urinary magnesium levels were negatively related with perceived stress (P = .01), anxiety (P = .016), and depression (P = .03). In controls, the number of stressful life events and the intensity of stressful life events was related positively with magnesium (P = .06, P = .02) levels and negatively with blood cortisol levels (P = .03, P = .004). Based on the variation between cases and controls in relations between CS dimensions and biochemical parameters, we hypothesize that CS may trigger a differential biological response in CaOx stone formers and controls, which in turn may promote or protect against CaOx stone formation.

Editorial Comment

Mental and emotional stress induced by external or internal stressors, or both, can exert biological effects. Some stress, such as when it is a temporary and acute reaction danger or a problem, is positive. Biological effects in this scenario would enhance one's ability to handle or avert the stressor. Continuous or chronic stress, however, is a negative reaction that may contribute variably and adversely to health. Chronic stress in susceptible individuals may contribute to, worsen, or even cause some conditions, including altered blood pressure, compromised immune status, headaches, cardiovascular problems, aberrant insulin metabolism, worsening of asthma, back pain, and arthritis, gastrointestinal problems, and mood and behavior changes. 1 Russell E. Koren G. Rieder M. et al. Hair cortisol as a biological marker of chronic stress: current status, future directions and unanswered questions. Psychoneuroendocrinology. 2012; 37: 589-601 Abstract Full Text Full Text PDF PubMed Scopus (595) Google Scholar A role for stress in cancer metastasis is proposed. 2 Moreno-Smith M. Lutgendorf S.K. Sood A.K. Impact of stress on cancer metastasis. Future Oncol. 2010; 6: 1863-1881 Crossref PubMed Scopus (269) Google Scholar In certain individuals, stress reduction appears to attenuate disease effects or decrease disease progression. 3 Schneider R.H. Grim C.E. Rainforth M.V. et al. Stress reduction in the secondary prevention of cardiovascular disease: randomized, controlled trial of transcendental meditation and health education in Blacks. Circ Cardiovasc Qual Outcomes. 2012; 5: 750-758 Crossref PubMed Scopus (133) Google Scholar , 4 Baker J. Costa D. Nygaard I. Mindfulness-based stress reduction for treatment of urinary urge incontinence: a pilot study. Female Pelvic Med Reconstr Surg. 2012; 18: 46-49 Crossref PubMed Scopus (18) Google Scholar But does this relationship extend to kidney stone formation or to unusually aggressive or more complex stone problems? Chronic Stress and Calcium Oxalate Stone Disease: Influence on Blood Cortisol and Urine CompositionUrologyVol. 82Issue 6PreviewTo evaluate the influence of chronic stress (CS) on urine composition of calcium oxalate (CaOx) stone patients and controls. Full-Text PDF ReplyUrologyVol. 82Issue 6PreviewThe Editorial Comment provides an excellent summary of our current knowledge of the relation between stress and disease. That some acute stress reactions are necessary to protect us in dangerous situations is well known. However, when this kind of reaction is maintained continuously over a long period, it can become a risk factor for a variety of chronic illnesses. The objective of our study was to examine a possible link between chronic stress, measured from a multidimensional point of view, with one specific chronic illness: calcium oxalate (CaOx) stone disease. Full-Text PDF

E164 Evaluation of a statistical model to predict calcium oxalate stone formers vs. patients without stone formation

E164 Evaluation of a statistical model to predict calcium oxalate stone formers vs. patients without stone formation

Using 24-Hour Urinalysis to Predict Stone Type

We determined the accuracy of 24-hour urinalysis in predicting stone type and identify the associations between 24-hour urine elements with stone type. We performed a retrospective review of 503 stone formers with stone composition analysis and 24-hour urinalysis available. Analysis of 24-hour urine elements across stone types was performed using Fisher's exact test and ANOVA. Multinomial logistic regression was used to predict stone type based on 24-hour urinalysis. A total of 280 (56%) patients had predominantly calcium oxalate, 103(20%) had uric acid, 93 (19%) had calcium phosphate, 16 (3%) had mixed and 11(2%) had other stone types. There were several significant patient characteristics and 24-hour urinalysis differences across stone type groups. The statistical model predicted 371 (74%) calcium oxalate, 78 (16%) uric acid, 52 (10%) calcium phosphate, zero mixed and 2 (less than 1%) other stone types. The model correctly predicted calcium oxalate stones in 85%, uric acid in 51%, calcium phosphate in 31%, mixed in 0% and other stone types in 18% of the cases. Of the predicted stone types, correct predictions were 61%, 69%, 56% and 71% for calcium oxalate, uric acid, calcium phosphate and other stones types, respectively. The overall accuracy was 64%. Plots were used to explore the associations between each 24-hour urine element with each predicted stone type adjusted for all the others urinary elements. A 24-hour urinalysis alone does not accurately predict stone type. However, it may be used in conjunction with other variables to predict stone composition.

Effects of dietary interventions on 24-hour urine parameters in patients with idiopathic recurrent calcium oxalate stones

The aim of this study is to investigate the effects of dietary factors on 24-hour urine parameters in patients with idiopathic recurrent calcium oxalate stones. A total of 108 of idiopathic recurrent calcium oxalate stones were included in the study. A 24-hour urinalysis was performed and metabolic abnormalities were measured for all of the patients. All of the patients were given specialized diets for their 24-hour urine abnormalities. At the end of first month, the same parameters were examined in another 24-hour urinalysis. Hyperoxaluria, hypernatruria, and hypercalciuria were found in 84 (77%), 43 (39.8%), and 38 (35.5%) of the patients, respectively. The differences between the oxalate, sodium, volume, uric acid, and citrate parameters before and after the dietary intervention were significant (p < 0.05). The calcium parameters were not significantly different before and after the intervention. We found that oxalate, sodium, volume, uric acid, and citrate—but not calcium—abnormalities in patients with recurrent calcium oxalate stones can be corrected by diet. The metabolic profiles of idiopathic calcium oxalate stone patients should be evaluated and the appropriate dietary interventions should be implemented to decrease stone recurrence.

Comparison of renal function and metabolic abnormalities of cystine stone patients and calcium oxalate stone patients in China

To compare renal function and metabolic abnormalities of cystine stone patients and calcium oxalate stone patients in China. Between 2008 and 2011, thirty cystine stone patients were involved in our study, and an equal number of age- and gender pair-matched patients with calcium oxalate stones. Non-stone forming individuals were elected as controls. The evaluation included blood chemistry studies and 24-h urine collection in both groups of patients. The cystine stone patients had higher mean values of serum blood urea nitrogen, urate and creatinine levels than patients in other two groups. With respect to urine risk factors, cystine stone patients had higher urinary citrate and lower urinary oxalate and creatinine than calcium oxalate stone patients. When compared to non-stone forming individuals, cystine stone patients had higher urinary urate excretion and lower urinary creatinine excretion. Metabolic abnormalities could be demonstrated in 80 % of the cystine stone patients and in 100 % of the calcium oxalate stone patients. We also compared urine risk factors among cystine stone patients with different urine cystine excretion (<1 mmol/24 h, 1-2 mmol/24 h and >2 mmol/24 h). No significant difference was found in urine risk factors among three groups. This study suggested that cystine stone patients were at greater risk for the loss of renal function than calcium oxalate stone patients, but the risk of the formation of calcium oxalate stones was lower. Our results also indicated that urinary cystine had little or no impact on the excretion of urine chemistries in cystine stone patients.

Aggregation of Urinary Microcrystallines with Different Sizes

Changes of average size ( d ), autocorrelation curve, aggregation state and stability of urinary crystallites in urine samples of calcium oxalate (CaOxa) stone patients and healthy controls with placement time were com- paratively studied using transmission electron microscopy (TEM) and nanoparticle size analyzer. The urine samples were filtrated by microporous membrane with a pore size of 0.22, 0.45, 1.2 and 3 μm, respectively. With the in- crease of placement time from 0 to 4 h, the d values of the crystallites in various filtrated urine of patients in- creased rapidly. The amplification of d (Δ d ) was 1439, 1557, 1534 and 1051 nm, respectively, when the place- ment time was up to 4 h. However, the Δ d of the urine crystallites of the controls was relatively small, which was only 474, 511, 567 and 433 nm, respectively. The urinary crystallites of the patients had rapid and large agglomera- tion and poor stability compared with those of the controls. The urinary crystallites of small size agglomerated more easily than those of large size. The results show that the rapid agglomeration of urine crystallites may play an im- portant role in the formation of CaOxa stones.