Uric Acid Stone Formation Research Articles

A comparison of the metabolic profiles of diabetic and non-diabetic uric acid stone formers

Introduction: The aim of this study was to compare the metabolic profiles of diabetic and non-diabetic patients with uric acid stones to understand whether preventive strategies should be tailored to reflect different causative factors.Methods: The results of the metabolic evaluation of patients with uric acid stones identified prospectively from the Metabolic Stone Clinic at St. Joseph’s Hospital, London, Canada were reviewed. Information included patients’ clinical histories, 24 hour urine collections, blood chemistry and stone analysis.Results: Complete data were obtained from 68 patients with uric acid stones. Twenty-two patients had diabetes. There were no statistically significant differences in mean age, body mass index, or history of gout. Among diabetics, pure uric acid stones were identified in 14 patients (63%) and mixed uric acid in 8 (36%). Pure uric acid stones were more common in the diabetic cohort (63% vs. 46%, p = 0.16). Urine pH, serum and urine uric acid levels and 24-hour urine volumes were similar in both groups. The diabetic group had an increased average oxalate excretion (424 μmol/d vs. 324 μmol/d, p = 0.003).Conclusion: The exact etiological basis for the higher oxalate excretion in diabetic uric acid stone formers is unclear. Whether this is a metabolic feature of diabetes, due to dietary indiscretion or the iatrogenic consequence of dietary advice requires further investigation.

2305 DOES BIOCHEMICAL RISK PROFILE MATCH STONE COMPOSITION FOR CALCIUM OXALATE, URIC ACID, AND MIXED STONE FORMERS?

INTRODUCTION AND OBJECTIVES: Previous studies have demonstrated differences in clinical and biochemical profiles of patients with pure uric acid (UA) and pure calcium oxalate (CaOx) calculi. However, to what degree they differ compared to patients with mixed CaOx/UA calculi is unknown. Therefore, we sought to determine how patients with mixed stone composition compare to the pure stone formers on 24-hour urine analysis. METHODS: We performed a retrospective review of 232 patients with both stone composition analysis and 24 hour urinalysis (Litholink®). Analysis of 24-hour urine constituents across the 3 stone groups (pure UA, pure CaOx and mixed CaOx/UA) was performed using univariable analysis of variance and multivariable linear regression models adjusting for urine volume, creatinine excretion and clinical and demographic factors. RESULTS: A total of 27 (11.6%) patients had mixed CaOx/UA, 122 (52.6%) had pure CaOx and 83 (35.8%) had pure UA calculi. Univariable analysis demonstrated significant differences between mixed CaOx/UA patients and pure CaOx patients for urine pH (mixed 5.63 0.49 vs. pure CaOx 5.93 0.51, p 0.009) and supersaturation (SS) of UA (mixed 1.84 1.09 vs. pure CaOx 1.26 0.93, p 0.01), and a significant difference between mixed CaOx/UA patients and pure UA patients for SS of CaOx (mixed 7.18 4.23 vs. pure UA 4.90 2.96, p 0.005). Multivariable analysis demonstrated that mixed CaOx/UA patients had no significant difference in SS CaOx as compared to pure CaOx patients (difference -0.27, p 0.66), while at the same time had no significant difference in SS UA as compared to pure UA patients (-0.07, p 0.69). Additionally, mixed stone composition patients had significantly lower urinary pH (-0.26, p 0.01) and urinary magnesium (-20.1 mg, p 0.019) than pure CaOx patients; these values were not significantly different that those of pure UA patients. (Table 1). CONCLUSIONS: The biochemical risk profile of patients who form mixed CaOx/UA calculi demonstrated abnormalities that promote both CaOx and UA stone formation. Dietary and medical management for patients with mixed stone composition may require treatment of both defects even if uric acid is the nidus for stone formation in this population.

Who makes uric acid stones and why—observations from a renal stones clinic

AimsExcessively acidic urine is the dominant factor in uric acid stone formation. Recent evidence implicating insulin resistance has revived interest in its causation. We reviewed data on uric acid stone...

Study on Nano- and Microcrystallites in Urines of Uric Acid Stone Patients

The presence of crystallites in urine is closely related to stones formation. In this article, the components, morphology of nano- and micro-crystallites in urines of 20 uric acid (UA) stone formers as well as their relationship with the formation of UAstones were comparatively studied using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The main constituent of urinary crystallites was uric acid. Their particle size distribution was highly uneven, ranging from several nanometers to several tens of micrometers, and obvious aggregation was observed. These results showed that there was close relationship among stone components, urinary crystallites composition and urine pH.

Association between Body Mass Index, Lipid Profiles, and Types of Urinary Stones

Objective: The purpose of this study was to determine the differences in body mass index (BMI), levels of cholesterol, and levels of triglycerides (TGs) among urolithiasis patients with different stone compositions. Materials and methods: Forty-nine patients who had a diagnosis of nephrolithiasis and had undergone open surgery or percutaneous surgery were included, and patients without urolithiasis were randomly selected as controls. Urinary stones were collected and analyzed using infrared spectroscopy. Data relating to patient’s age, BMI at diagnosis, serum total cholesterol (TC), high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol (LDL-C) were collected. The stone groups including calcium oxalate monohydrate-calcium oxalate dihydrate (COM-COD), COM, and uric acid were compared with one another and with the control group. In addition, the stone formers group (COM-COD, COM, uric acid, calcium phosphate, and mixed-type stones) was compared to the control group. Results: BMI, TC, and TG levels were significantly higher in stone formers compared with the control group; this association of BMI and TC with stone formation was more prominent in uric acid and COM-COD stone formers, but there was no such prominence for COM stones. LDL-C levels in COM-COD stone formers were significantly higher when compared with COM stone formers. Conclusion: Elevated BMI, hypercholesterolemia, and hyperlipidemia, which are leading components of metabolic syndrome, may be associated with different types of urinary stone formation.

The diurnal variation in urine acidification differs between normal individuals and uric acid stone formers

Many biologic functions follow circadian rhythms driven by internal and external cues that synchronize and coordinate organ physiology to diurnal changes in the environment and behavior. Urinary acid-base parameters follow diurnal patterns and it is thought these changes are due to periodic surges in gastric acid secretion. Abnormal urine pH is a risk factor for specific types of nephrolithiasis and uric acid stones are typical of excessively low urine pH. Here we placed 9 healthy volunteers and 10 uric acid stone formers on fixed metabolic diets to study the diurnal pattern of urinary acidification. All showed clear diurnal trends in urinary acidification but none of the patterns were affected by inhibitors of the gastric proton pump. Uric acid stone formers had similar patterns of change through the day but their urine pH was always lower compared to healthy volunteers. Uric acid stone formers excreted more acid (normalized to acid ingestion) with the excess excreted primarily as titratable acid rather than ammonium. Urine base excretion was also lower in uric acid stone formers (normalized to base ingestion) along with lower plasma bicarbonate concentrations during part of the day. Thus, increased net acid presentation to the kidney and the preferential use of buffers, other than ammonium, result in much higher concentrations of un-dissociated uric acid throughout the day and consequently an increased risk of uric acid stones.

Comparison of secondary signs as shown by unenhanced helical computed tomography in patients with uric acid or calcium ureteral stones

Unenhanced helical computed tomography (UHCT) has evolved into a well-accepted diagnostic method in patients with suspected ureterolithiasis. UHCT not only shows stones within the lumen of the ureter, it also permits evaluation of the secondary signs associated with ureteral obstruction from stones. However, there we could find no data on how secondary signs might differ in relation to different compositions of ureteral stones. In this study, we compared the degree of secondary signs revealed by UHCT in uric acid stone formers and in patients forming calcium stones. We enrolled 117 patients with ureteral stones who underwent UHCT examination and Fourier transform infra-red analysis of stone samples. Clinical data were collected as follows: age, sex, estimated glomerular filtration rate (eGFR), urine pH, and radiological data on secondary signs apparent on UHCT. The uric acid stone formers had significantly lower urine pH and eGFR in comparison to calcium stone formers, and on UHCT they also had a higher percentage of the secondary signs, including rim sign (78.9% vs. 60.2%), hydroureter (94.7% vs. 89.8%), perirenal stranding (84.2% vs. 59.2%) and kidney density difference (73.7% vs. 50.0%). The radiological difference was statistically significant for perirenal stranding (p=0.041). In conclusion, we found that UHCT scanning reveals secondary signs to be more frequent in patients with uric acid ureteral stones than in patients with calcium stones, a tendency that might result from an acidic urine environment.

Proteomic Study of Renal Uric Acid Stone

To analyze urinary uric acid stone matrix proteins (SMP) with mass spectrometry (MS) to evaluate the mechanisms of uric acid stone formation. SMP plays an important role in urinary stone formation. Several proteomic studies apply to calcium-containing stones have been reported; however no proteomic study for urinary uric acid stone has been reported. Pure kidney uric acid stones from 5 individuals were demineralized, and SMPs were isolated. The obtained proteins were analyzed with reverse-phase liquid chromatography-tandem MS. The acquired data were searched against a Swiss Prot human protein database using Matrix Science, Mascot. The identified proteins were submitted to the AmiGO Web site for gene ontology analysis. They were also sumitted to Metacore software and Kyoto Encyclopedia of Genes and Genomes website (KEGG) for pathway analysis. MS-determined protein expressions were verified by immunoblot. MS analysis identified 242 proteins from 5 proteomic results and the number of the identified protein of each result ranged from 52 to 156. Metacore software analysis suggested that inflammation may play an important role for kidney uric acid stone formation. Endogenous metabolic pathways were also analyzed and submitted to KEGG Web site, which revealed that these proteins may participate in fat metabolism. Five identified proteins were selected for immunoblot validation, and 3 proteins were confirmed. Our results suggest that inflammatory process may play a role in kidney uric acid stone formation. Our endogenous metabolic pathway analysis data revealed that these proteins may participate in lipid metabolism. Whether this finding implies a relation between lipotoxicity and kidney uric acid stone former requires further investigation.

Effect of α1-microglobulin and β2-microglobulin on calcium oxalate urine stone formation

Objective To define the difference of urine analysis result,α1-microglobulin (α1-MG) and β2-microglobulin ( β2-MG) between those patients suffering from calcium oxalate stone,non-calcium oxalate stone and non-urolithiasis controls at the same time period. Methods Data from 100 patients admitted to the Department of Urology,First Affiliated Hospital of Anhui Medical University from July,2010 to September,2010 were reviewed.66 patients (45 men,21 women) suffered from urolithiasis,and 34 patients (22 men,12 women) were non-urolithiasis.Patients' ages in urolithiasis group varied from 13 to 78 years and the male to female ratio was 2.1∶1.0.The patients in non-urolithiasis controlgroup aged from 12 to 80 years and the male to female ratio was 1.8∶1.0.Blood and urine were taken from the patient the next morning after admission.The biochemistry from blood and 24 h urine were measured by automatic biochemistry analyzer.The α 1-MG and β2-MG content were measured by radioimmunoassay.The stone compositions were analyzed by infrared spectroscopy. Results There was difference in the levels of serum creatinine and blood urea nitrogen among three groups ( P ＜ 0.05).In controls,those with calcium oxalate stone had higher level of urinary α1-MG and β2-MG,but there were no differences in the urinary electrolyte levels.Group of non-calcium oxalate stones urinary uric acid levels were higher than calcium oxalate and control groups,the difference was statistically significant. Conclusions In the formation of uric acid stones,uric acid increased as independent risk factors.α1-MG,β2-MG may promote the formation of calcium oxalate stones. Key words: Urinary calculi; Stone analysis; 24 h urine analysis; Electrolytes; M icroglobulin

A comparison of the metabolic profiles of diabetic and non-diabetic uric acid stone formers

The aim of this study was to compare the metabolic profiles of diabetic and non-diabetic patients with uric acid stones to understand whether preventive strategies should be tailored to reflect different causative factors. The results of the metabolic evaluation of patients with uric acid stones identified prospectively from the Metabolic Stone Clinic at St. Joseph's Hospital, London, Canada were reviewed. Information included patients' clinical histories, 24 hour urine collections, blood chemistry and stone analysis. Complete data were obtained from 68 patients with uric acid stones. Twenty-two patients had diabetes. There were no statistically significant differences in mean age, body mass index, or history of gout. Among diabetics, pure uric acid stones were identified in 14 patients (63%) and mixed uric acid in 8 (36%). Pure uric acid stones were more common in the diabetic cohort (63% vs. 46%, p = 0.16). Urine pH, serum and urine uric acid levels and 24-hour urine volumes were similar in both groups. The diabetic group had an increased average oxalate excretion (424 μmol/d vs. 324 μmol/d, p = 0.003). The exact etiological basis for the higher oxalate excretion in diabetic uric acid stone formers is unclear. Whether this is a metabolic feature of diabetes, due to dietary indiscretion or the iatrogenic consequence of dietary advice requires further investigation.

IMPROVING THE INTERPRETATION OF URETEROSCOPIC BIOPSIES: USE OF BOUIN'S FIXATIVE

Introduction: The aim of this study was to compare the metabolic profiles of diabetic and non-diabetic patients with uric acid stones to understand whether preventive strategies should be tailored to reflect different causative factors. Methods: The results of the metabolic evaluation of patients with uric acid stones identified prospectively from the Metabolic Stone Clinic at St. Joseph’s Hospital, London, Canada were reviewed. Information included patients’ clinical histories, 24 hour urine collections, blood chemistry and stone analysis. Results: Complete data were obtained from 68 patients with uric acid stones. Twenty-two patients had diabetes. There were no statistically significant differences in mean age, body mass index, or history of gout. Among diabetics, pure uric acid stones were identified in 14 patients (63%) and mixed uric acid in 8 (36%). Pure uric acid stones were more common in the diabetic cohort (63% vs. 46%, p 0.16). Urine pH, serum and urine uric acid levels and 24-hour urine volumes were similar in both groups. The diabetic group had an increased average oxalate excretion (424 mol/d vs. 324 mol/d, p 0.003). Conclusion: The exact etiological basis for the higher oxalate excretion in diabetic uric acid stone formers is unclear. Whether this is a metabolic feature of diabetes, due to dietary indiscretion or the iatrogenic consequence of dietary advice requires further investigation.

E64 Uric acid stone formation correlates to high body mass index, diabetes and dyslipidemia. A retrospective analysis of 600 stone formers

E64 Uric acid stone formation correlates to high body mass index, diabetes and dyslipidemia. A retrospective analysis of 600 stone formers

Uric Acid Nephrolithiasis: A Systemic Metabolic Disorder.

Uric acid nephrolithiasis is characteristically a manifestation of a systemic metabolic disorder. It has a prevalence of about 10% among all stone formers, the third most common type of kidney stone in the industrialized world. Uric acid stones form primarily due to an unduly acid urine; less deciding factors are hyperuricosuria and a low urine volume. The vast majority of uric acid stone formers have the metabolic syndrome, and not infrequently, clinical gout is present as well. A universal finding is a low baseline urine pH plus insufficient production of urinary ammonium buffer. Persons with gastrointestinal disorders, in particular chronic diarrhea or ostomies, and patients with malignancies with a large tumor mass and high cell turnover comprise a less common but nevertheless important subset. Pure uric acid stones are radiolucent but well visualized on renal ultrasound. A 24 h urine collection for stone risk analysis provides essential insight into the pathophysiology of stone formation and may guide therapy. Management includes a liberal fluid intake and dietary modification. Potassium citrate to alkalinize the urine to a goal pH between 6 and 6.5 is essential, as undissociated uric acid deprotonates into its much more soluble urate form.

Clinical and metabolic evaluation of Korean patients with urolithiasis

Background. The purpose of the present study was to conduct a comprehensive evaluation of clinical and metabolic factors in order to determine the characteristics of urolithiasis in a Korean population, compared with other ethnic groups. In addition, clinical and metabolic factors associated with calcium oxalate (CaOx) and uric acid (UA) stone formation were compared. Methods. A total of 211 Korean patients with urolithiasis were analysed. Biochemical components in 24-hour urine were determined and the relative supersaturation (RSS) was calculated using the EQUIL 3 software program. Physical analysis of stone composition using Fourier Transform-Infrared spectrometry (FT-IR), blood chemistry, and demographics were also investigated. Results. A previous history of urolithiasis and male gender were found to be clinical risk factors related to urolithiasis. Metabolic abnormalities, including hypercalciuria, low urine volume, natriuresis, hypocitraturia, and hyperoxalaturia were commonly found in 24-hour urine. Korean patients had higher calcium, lower citrate, lower phosphate, lower urine volume, and higher RSS with respect to UA than Caucasian patients. Patients with CaOx stone formation (n = 100) were younger and excreted a higher level of calcium and higher UA at a higher pH than patients with UA stones (n = 37). A significant difference in RSS was observed with respect to CaOx, while there was no significant difference in RSS with respect to UA between them. Conclusions. Metabolic abnormalities, including hypercalciuria, low urine volume, natriuresis, hypocitraturia, and hyperoxalaturia were important findings in Korean patients with urolithiasis. In addition, clinical and metabolic characteristics of CaOx stone formers differed in comparison with UA stone formers.

2149 WEIGHT LOSS INTERVENTION REDUCES THE RISK OF KIDNEY STONE FORMATION IN A RAT MODEL OF METABOLIC SYNDROME

You have accessJournal of UrologyStone Disease: Basic Research1 Apr 20112149 WEIGHT LOSS INTERVENTION REDUCES THE RISK OF KIDNEY STONE FORMATION IN A RAT MODEL OF METABOLIC SYNDROME Yumiko Sasaki, Yasuo Kohjimoto, Akinori Iba, Nagahide Matsumura, and Takeshi Inagaki Yumiko SasakiYumiko Sasaki Wakayama City, Japan More articles by this author , Yasuo KohjimotoYasuo Kohjimoto Wakayama City, Japan More articles by this author , Akinori IbaAkinori Iba Wakayama City, Japan More articles by this author , Nagahide MatsumuraNagahide Matsumura Wakayama City, Japan More articles by this author , and Takeshi InagakiTakeshi Inagaki Wakayama City, Japan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.2360AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES We have previously reported that metabolic syndrome (MetS) increases the risk of kidney stone formation through low urinary pH, decreased citrate excretion, and increased uric acid and calcium excretion, and that the improving insulin resistance by pioglitazone reversed low urinary pH (BJU Int 106: 1550–1554, 2010). However, it has not been studied whether weight loss intervention reduces the risk of kidney stone formation. The present study examined the effect of diet restriction and/or exercise on the urinary stone risk parameters in a rat model of MetS. METHODS Four-week-old male Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of MetS, were randomly assigned to 3 groups of 6 rats each. Control rats were sedentary with free access to standardized diet. Food restricted (FR) rats were sedentary with 30% reduction of daily food ingestion compared to the control rats. Exercise-trained (ET) rats were provided voluntary access to running wheels in combination with 30% food restriction. All rats were allowed free access to drinking water. After 16 weeks blood and 24-hour urine samples were collected. RESULTS FR rats and ET rats showed significantly lower body weight, serum triglyceride, cholesterol, glucose, insulin, homeostasis model assessment ratio (HOMA-R) compared to control rats. In these weight intervention groups, urinary pH and citrate excretion were significantly higher and ion-activity product of calcium oxalate [AP (CaOx)] index, an indicator of CaOx crystal formation, was significantly lower than those of control rats (p<0.01, Figure). Other urinary parameters were not significantly different among the groups. When 24-week-old male OLETF, that had already developed type 2 diabetes, were submitted to the same protocol, similar results were obtained. CONCLUSIONS The results indicate that weight loss intervention reduces the risk of uric acid stone formation by improving low urine pH and CaOx stone formation by increasing urinary citrate excretion. The present study provides the first theoretical evidence to recommend weight loss intervention program for nephorolithiasis patients with MetS. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e860-e861 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Yumiko Sasaki Wakayama City, Japan More articles by this author Yasuo Kohjimoto Wakayama City, Japan More articles by this author Akinori Iba Wakayama City, Japan More articles by this author Nagahide Matsumura Wakayama City, Japan More articles by this author Takeshi Inagaki Wakayama City, Japan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Four cases of postrenal renal failure induced by renal stone associated with rotavirus infection

Rotavirus (RV) is a common pathogen that causes acute gastroenteritis in childhood. Some cases with RV infection also have prerenal renal failure induced by dehydration associated with vomiting and diarrhea. Here, we report 4 patients with RV infection who developed postrenal renal failure induced by urinary tract obstruction with uroammoniac calculi or crystals. The patients did not have metabolic disorders or abnormalities of the urinary tract, and increased urinary excretion of uric acid was not recognized at discharge. In addition, no abnormalities in the uric acid transporter (URAT1) were found in any of the patients. Uric acid stone formation was considered to have originated from the low pH caused by dehydration and the increase of urinary uric acid excretion from damaged cells.

Cause of uric acid stones in rotavirus-associated gastroenteritis

gastroenteritis. Fujita et al. suspected that there may be an association between renal hypouricemia and uric acid stone formation in patients with HRV-associated gastroenteritis due to the number of cases, including our own, that have been reported, primarily in Japan (2-6). Urate urolithiasis is rarely seen in children. It is generally associated with an increased urinary concentration of urate and its subsequent deposition. Hyperuricuria and uric acid nephrolithiasis are mainly caused by the increased excretion or disturbed reabsorption of uric acid by the renal proximal tubular cells: the former is accompanied with hyperurice- mia, while the latter may be associated with hypouricemia. Hyperuricemia is observed in children with tumor lysis syndrome, Lesch-Nyhan syndrome and hypoxanthine-

Insulin resistance increases the risk of urinary stone formation in a rat model of metabolic syndrome

To investigate the association between metabolic syndrome and urinary stone disease, and whether insulin resistance associated with adiposity affects the risk of urinary stone formation, using a rat model of metabolic syndrome. Four-week-old male Otsuka Long-Evans Tokushima 'Fatty' (OLETF, a model of human type 2 diabetes and metabolic syndrome) rats, and Long-Evans Tokushima (LETO, a non-diabetic control) rats (10 each) were given a standardized diet and free access to water. Body weight and serum and urinary biochemistry were determined every 4 weeks. Ten-week-old male OLETF and LETO rats were divided into three groups of nine each and treated with vehicle or oral administration of 3 or 10 mg/kg/day pioglitazone, an agent that improves insulin resistance. After 4 weeks, body weight and serum and urinary biochemistry were determined. The OLETF rats had significantly lower urinary pH and citrate excretion, and higher urinary uric acid and calcium excretion, than the LETO rats, with increases in body weight, serum triglyceride, glucose and insulin. The administration of pioglitazone to the OLETF rats for 4 weeks significantly increased urinary pH dose-dependently. There was no change in the urinary excretion of citrate, uric acid, calcium, oxalate or magnesium. These results indicate that metabolic syndrome causes the changes in urinary constituents, leading to increased risk of both uric acid and calcium stone formation. Improvement in insulin resistance, a central cause of metabolic syndrome, might prevent uric acid stone formation by raising urinary pH.

Intra-tubular deposits, urine and stone composition are divergent in patients with ileostomy

Patients with ileostomy typically have recurrent renal stones and produce scanty, acidic, sodium-poor urine because of abnormally large enteric losses of water and sodium bicarbonate. Here we used a combination of intra-operative digital photography and biopsy of the renal papilla and cortex to measure changes associated with stone formation in seven patients with ileostomy. Papillary deformity was present in four patients and was associated with decreased estimated glomerular filtration rates. All patients had interstitial apatite plaque, as predicted from their generally acid, low-volume urine. Two patients had stones attached to plaque; however, all patients had crystal deposits that plugged the ducts of Bellini and inner medullary collecting ducts (IMCDs). Despite acid urine, all crystal deposits contained apatite, and five patients had deposits of sodium and ammonium acid urates. Stones were either uric acid or calcium oxalate as predicted by supersaturation, however, there was a general lack of supersaturation for calcium phosphate as brushite, sodium, or ammonium acid urate because of the overall low urine pH. This suggests that local tubular pH exceeds that of bulk urine. Despite low urine pH, patients with an ileostomy resemble those with obesity bypass, in whom IMCD apatite crystal plugs are found. They are, however, unlike these bypass patients in having interstitial apatite plaque. IMCD plugging with sodium and ammonium acid urate has not been found previously and appears to correlate with formation of uric acid stones.

Calcium oxalate stone and gout

Gout is well known to be produced by increased uric acid level in blood. The objective of this paper is to assess the relationship between gout and calcium oxalate stone formation in the humans. 48 patients with combination of gout and calcium oxalate stone problem were included. The biochemical values of this group were compared with 38 randomly selected uric acid stone patients with gout, 43 stone patients with gout alone, 100 calcium oxalate stone patients without gout and 30 controls, making a total of 259 patients. Various biochemical parameters, namely serum calcium, phosphorus and uric acid and 24-h urine calcium, phosphorus, uric acid, oxalate, citrate and magnesium were analysed. ANOVA and Duncan's multiple-range tests were performed to assess statistical significance of the variations. The promoters of stone formation, namely serum calcium (P < 0.05), phosphorus (P < 0.05) and uric acid (P < 0.05) and urine calcium (P < 0.05), uric acid (P < 0.05) and oxalate (P < 0.05) were significantly variable in the different groups. The inhibitor citrate (P < 0.05) was also significantly variable. Multiple-range test showed that the promoters, namely serum calcium (P < 0.05) and urine uric acid (P < 0.05) were in a significantly higher range in the gouty patients, gouty uric acid stone patients and gouty calcium oxalate stone patients compared to the non-gouty patients and controls. Urine oxalate (P < 0.0001) was in the highest range in the gouty calcium oxalate or gouty uric acid stones patients. The inhibitor urine citrate (P < 0.001) was significantly lower in the gouty, gouty uric acid and gouty calcium oxalate patients. Serum uric acid was highest in the non-stone gouty patients, followed by the gouty uric acid stone formers and gouty calcium oxalate stone patients. The high values of promoters, namely uric acid and calcium in the gouty stone patients indicate the tendency for urinary stone formation in the gouty stone patients. There is probably a correlation between gout and calcium oxalate urinary stone. We presume this mechanism is achieved through the uric acid metabolism. The findings point to the summation effect of metabolic changes in development of stone disease.