Urolithiasis in Okinawa, Japan: A relatively high prevalence of uric acid stones

AIM: The aim of the present study was to investigate the composition of urinary tract stones in patients from Okinawa, the most southern island group of Japan. METHODS: The study was conducted by 12 hospitals in Okinawa. A total of 1816 urinary tract calculi were obtained from 1816 patients (1323 males; 493 females). The patients had a mean age of 53 +/- 15.3 years (mean +/- SD). The calculi were examined to determine their chemical composition. Stone samples were analyzed by computed infrared spectrophotometer. RESULTS: Pure stones comprised 58.4% of the total, with calcium oxalate stones accounting for 40% (21% monohydrate [whewellite]; 6.6% dihydrate [weddellite]; and 12.4% combined monohydrate and dihydrate stones), uric acid/urate stones for 9.6%, calcium phosphate stones for 5.1%, and struvite stones for 3.7%. The other 41.6% of the stones consisted of calcium oxalate mixed with other components. The male-to-female ratio was 2.7:1. CONCLUSION: In our series, calcium oxalate stones accounted for 81.6% of the urinary tract calculi, while uric acid/urate stones accounted for 15.8%. Uric acid stones, predominantly the anhydrous and/or dihydrate forms, showed a relatively high prevalence. Calcium oxalate stones, predominantly in the form of whewellite, showed a high prevalence among pure calculi; while the predominant combinations among mixed calculi were weddellite + calcium phosphate and whewellite + uric acid/urate.     

Ammonium acid urate calculi: a reevaluation of risk factors

PURPOSE: We reevaluate the demographic and metabolic risk factors for ammonium acid urate stones. MATERIALS AND METHODS: Since 1986, 23 women and 21 men ranging in age from 20 to 81 years (mean 48.7) were treated for stones partly composed of ammonium acid urate. Stone composition ranged from 2 to 60% ammonium acid urate (mean 24.1) of the total stone mass. No patient had a pure ammonium acid urate stone, although 11 (25%) had stones with ammonium acid urate as the predominant crystal. RESULTS: In the 44 patients 1 or more potential risk factors for ammonium acid urate were identified. Of the patients 11 (25%) had a history of inflammatory bowel disease with 10 (22.7%) having undergone ileostomy diversion, 6 (13.6%) admitted to a history of significant laxative use or abuse, 18 (40.9%) were morbidly obese, 16 (36.4%) had a history of recurrent urinary tract infections and 9 (20.5%) had a history of recurrent uric acid stones. CONCLUSIONS: Patients clearly at risk for stones with an ammonium acid urate component include those with a history of inflammatory bowel disease and ileostomy diversion or laxative abuse. Other factors that may potentially enhance ammonium acid urate stone formation include morbid obesity, recurrent uric acid calculi and recurrent urinary tract infection. A careful history followed by further metabolic evaluation is warranted in these patients.     

Ammonium acid urate stone due to laxative abuse: a case report

We report a case of ammonium acid urate stone due to laxative abuse. A 27-year-old female complained of left flank pain. Computed tomography revealed bilateral ureter stones (right 16.5 x 9.0 mm; left 4 mm), while left ureter stone was radiolucent on the plain X ray film. Bilateral hydronephrosis was seen, but no therapy was performed for the right stone, because 99mTc-MAG3 scintigraphy revealed that right kidney had no function. The left stone was successfully removed by transurethral approach. The stone was revealed to be an ammonium acid urate by infrared spectrophotometry. She had been taking many laxatives (bisacodyl, sennoside, aloe extract) for 12 years to control her body weight. Ammonium acid urate stones are rarely seen in developed countries. We have reviewed 9 cases in Japan, describing ammonium acid urate stones due to laxative abuse. Among these patients, 24-hour urine volume and excretion in urinary sodium were decreased, and serum aldosterone was increased. The involvement of laxative abuse should be considered when ammonium acid urate is formed in a woman with a low body mass index.     

结石红外光谱自动分析系统在尿路结石成分分析中的应用

目的 评价红外光谱自动分析系统检测尿路结石成分的临床应用价值.方法 尿路结石标本1450例.男1032例,女418例.年龄6个月～88岁.男性平均年龄(41.7±15.3)岁,女性(42.0±15.6)岁.肾结石875例(60.34%),输尿管结石504例(34.76%),膀胱结石71例(4.90%).均采用LIIR型结石红外光谱自动分析系统分析.解析结果均行红外光谱人工解析验证,必要时辅以偏光显微镜、X线衍射或化学方法进行验证. 结果在结石总体构成比上,一水草酸钙结石714例(49.24%),碳酸磷灰石结石444例(30.62%),无水尿酸结石93例(6.41%),二水草酸钙结石92例(6.34%),六水磷酸铵镁结石28例(1.93%),胱氨酸结石23例(1.59%),尿酸铵结石20例(1.38%),二水尿酸结石16例(1.10%),二水磷酸氢钙结石12例(0.83%),一水尿酸钠结石2例(0.14%),碳酸钙结石1例(0.07%),其他5例(0.34%).结石的组合成分上,混合性结石1053例(72.62%),单一成分结石仅397例(27.38%).混合性结石主要为含钙类结石.其中15例婴幼儿结石为食用三聚氰胺污染奶粉所致,成分为二水尿酸与尿酸铵的混合结石.验证结果表明,结石主要成分误检6例(0.41%),将无水尿酸误检为尿酸铵或碳酸磷灰石;漏检9例(0.62%),其中漏检六水磷酸铵镁或碳酸磷灰石7例,性质不明2例.在2种和3种成分的混合性结石中,含量相对低的成分各漏检6例和10例,均为六水磷酸铵镁或碳酸磷灰石. 结论结石红外光谱自动分析系统分析尿路结石成分具有准确、自动、快捷等优点,适合临床常规使用.

Abstract：

Objective To determine the value of applying LIIR Automatic Analysis System of Infrared Spectroscopy in analyzing urinary stone composition. Methods 1450 samples of urinary stones were collected from 1032 male and 418 female patients. The age of patients ranged from 6 months to 88 years. The mean ages were 41.7±15.3 and 42.0±15.6 years for male and female patients, respectively. Of 1450 stones, 875 cases were located in kidney (60.34%), 504 cases in ureter (34.76%) and 71 cases in bladder (4.90%). All stones were analyzed by LIIR Automatic Analysis System of Infrared Spectroscopy (Tianjin). Analysis results were reevaluated by the artificial analysis of spectrogram, if necessary, with polarization microscope, chemical analysis, and X-ray diffraction.Results Calcium oxalate monohydrate stones were found in 714 cases (49. 24%), carbonate apatite stones in 444 cases (30.62%), anhydrous uric acid stones in 93 cases (6.41%), calcium oxalate dihydrate stones in 92 cases (6. 34 % ), ammonium magnesium phosphate hexahydrate stones in 28 cases (1.93%), cystine stones in 23 cases (1.59%), ammonium urate stones in 20 cases (1.38%), uric acid dihydrate stones in 16 cases (1.10%), brushite stones in 12 cases (0.83%), sodium urate monohydrate stones in 2 cases (0. 14%), calcium carbonate stones in 1 cases (0. 07%), and other stone types in 5 cases (0. 34%). Most urinary stones were composed of 2 or more compositions, and pure stones were only observed in 397 cases (27.38%). Most of the mixed stones contained calcium and non-calcium mixed stone was rarely observed. In addition, 15 stones were found in infants who had consumed melamine-contaminated milk powder. These stones were composed of uric acid dihydrate and ammonium urate. The results of reevaluation by artificial analysis showed the following: among pure and mixed stones, false detection occurred in 6 cases (0.41%), of which the composition was ammonium urate or carbonate apatite determined by automatic system but the true composition was anhydrous uric acid. False negative detection occurred in 9 cases (0.62%), of which the composition was ammonium magnesium phosphate hexahydrate or carbonate apatite in 7 cases, but in other 2 cases the composition could not be determined by artificial analysis. The false negative detection of components with relatively low content occurred in 6 cases and 10 cases in stones with 2 components and 3 components, respectively. The undetected composition in these cases was ammonium magnesium phosphate hexahydrate or carbonate apatite. Conclusion Automatic Analysis System of Infrared Spectroscopy has many advantages in accuracy, automation and is quick in analyzing the composition of urinary stones, and is worthy of promotion in clinical use.     

Two cases of ammonium acid urate urinary stones related to anorexia nervosa and laxative abuse

We report two cases of urolithiasis related to anorexia nervosa and laxative abuse. Case 1: A 21-year-old woman was referred to our hospital because of left flank pain. A left ureteral stone, 10 x 6 mm in size, was successfully fragmented by extracorporeal shock-wave lithotripsy (ESWL), but she experienced repetitive formation of bilateral urinary stones and double J stent encrustation which required 13 sessions of ESWL, one session of transurethral ureterolithotripsy and one session of cystolithotripsy over a period of 5 years. All stones were comprised of pure ammonium acid urate. It was later revealed that she was diagnosed with anorexia nervosa at 15 years old and had suffered from laxative abuse (bisacodyl, 300-500 mg/day) ever since. Case 2: A 18-year-old woman was referred to our hospital because of left lower abdominal pain. A left renal stone, 15 x 10 mm in size, was successfully fragmented by ESWL, but she had double J stent encrustation which was managed by cystolithotripsy. All stones were comprised of pure ammonium acid urate. She was later diagnosed with anorexia nervosa and it turned out that she had suffered from an eating disorder and laxative abuse (bisacodyl, 200 mg/day) since the age of 15 years. Both patients had marked decrease in urine volume, hyponatremia and hypokalemia. Anorexia nervosa and laxative abuse should be suspected whenever a woman has an ammonium acid urate stone in sterile urine because the treatment of these disorders is crucial to the prevention of repetitive formation of urinary stones.     

gamma-Carboxyglutamic acid, a component in human pediatric bladder stones containing calcium salts

The amino acid gamma-carboxyglutamic acid (Gla) has been previously detected in the vitamin K-requiring blood clotting factors, proteins of calcified vertebrate tissue, renal tissue, plasma protein C, ectopic calcifications, and calcium-containing renal calculi. This paper reports the presence of Gla in the EDTA-soluble, non-dialyzable material recovered from human pediatric bladder stones containing calcium salts. In bladder stones composed of calcium oxalate, uric acid and ammonium acid urate, 73 Gla residues per 1,000 amino acid residues were detected. Bladder stones composed of calcium oxalate, uric acid, ammonium acid urate, and hydroxyapatite contained 48 Gla residues per 1,000 amino acid residues present. No Gla was detected in the predominantly magnesium ammonium phosphate (struvite) bladder stones. These results with human bladder stones from children under 10 years of age are consistent with the observations from adult patients in which Gla was detected in the calcium-containing renal calculi but not in the non-calcium-containing renal calculi. The present study adds to the growing body of information concerning the possible role of Gla in normal and abnormal calcium metabolism.     

A case of ammonium urate urinary stones with anorexia nervosa

A 27-year-old woman had been suffering from bulimia and habitual vomiting for about 7 years and was incidentally found to have right renal stones by computed tomography. She was referred to our hospital for the treatment of these caluculi. On admission, she presented with hypokalemia, hypochloremia and metabolic alkalosis and was diagnosed with anorexia nervosa. Following successful removal by percutaneous nephrolithotripsy and extracorporeal shockwave lithotripsy the stones were found to consist of pure ammonium urate. Since the urine of an anorexia nervosa patient tends to be rich in uric acid and ammonium, anorexia nervosa seems to be associated with ammonium urate urinary stones.     

Analysis of calculi by infrared spectroscopy in children from the Moroccan mid-Atlas region

Calculi from 45 Moroccan children aged between 2 and 15 years underwent morphological and infrared spectrometric analysis. The stones were three times more frequent in males than females (M/F = 3.09). Whewellite was the main component in 51.1% of cases and in 44.4% of stone nuclei, wheddellite in 8.9% of stones and nuclei, carbapatite in 6.7% of stones and 8.9% of nuclei, struvite in 15.6% of stones and 11.1% of nuclei. Ammonium hydrogen urate and uric acid were predominant respectively in 8.9% and 6.7% of stones and in 15.6% and 11.1% of nuclei. In addition to whewellite, struvite and ammonium hydrogen urate were the main components of bladder stones from both sexes. With respect to their calculi, whewellite was present in 84.4% of cases and wheddellite in 26.7%. Purines were present in 46% of calculi, especially as ammonium urate (28.9%) and uric acid (15.6%). Calcium phosphates as the main components were infrequent. In contrast, they were frequently identified in urinary calculi from children, respectively 64.4% and 40% for carbapatite and amorphous carbonated calcium phosphate.     

Pediatric urolithiasis in Armenia: a study of 198 patients observed from 1991 to 1999

To study prospectively the risk factors and etiology of urolithiasis in all stone patients aged <15 years admitted from 1991 to 1999 to the Arabkir hospital in Yerevan. Stones were obtained by surgery (64%), extracorporeal shockwave lithotripsy (ESWL) (7%) or cystoscopic extraction (4%); 25% passed spontaneously. All were examined by infrared spectroscopy, and spot urines were analyzed chemically. 198 patients, 180 (68% males) with renal stones and 18 (83% males) with primary bladder stones, were studied. Calcium oxalate (CaOx) was the predominant constituent in 62% of the kidney stones, followed by struvite (17%), calcium phosphate (7%), uric acid (7%), ammonium acid urate (5%), and cystine (2%). Bladder stones contained CaOx in 72%, uric acid in 22% and ammonium acid urate in 6% of patients. Etiology was obviously metabolic in 5% and possibly metabolic in 26%. Twenty percent of stones were infectious, and 19% were endemic (9% bladder and 10% kidney stones); 4% were secondary to urinary stasis with malformation but no infection. Etiology in 26% remained unknown. Stone composition and metabolic etiology are similar to that in central Europe and North America. In contrast, infectious calculi and particularly endemic stones are still common, although becoming less so now. Urolithiasis in Armenia thus reflects the transition from a rural to an urban society. Received: 17 January 2001 / Revised: 24 April 2001 / Accepted: 24 April 2001     

Infrared spectroscopic analysis of urinary stones (including stones induced by melamine-contaminated milk powder) in 189 Chinese children

Aim

The aim of the study was to investigate the composition of the stones in Chinese children with urolithiasis, including peculiar stones induced by melamine-contaminated milk powder.

Materials and Methods

Between 1999 and 2009, 189 urinary stones from children of East China were received at our institution. Among them, 12 stones were received from pediatric stone formers with a history of consuming melamine-contaminated milk powder in 2008; and the remaining stones were defined as “natural” stones. All stones were analyzed by Fourier transform infrared spectroscopy.

Results

Among 177 “natural” stones, whewellite stone (49.72%) was observed most frequently followed by weddellite stone (15.25%), uric acid anhydrous stone (9.6%), carbapatite stone (9.04%), cystine stone (9.04%), ammonium acid urate stone (4.52%), struvite stone (2.26%), and sodium urate stone (0.56%). Twelve young children who consumed melamine-contaminated milk powder were younger than 3 years, and their stones were composed of a mixture of uric acid dihydrate and ammonium acid urate based on Fourier transform infrared spectroscopy. In addition, the stones were radiolucent and could be dissolved by urine alkalinization.

Conclusions

Our study emphasizes the relatively high rate of calcium oxalate stones and cystine stones, and the relatively low rate of struvite stones in Chinese children with urolithiasis. The stones caused by melamine-contaminated milk powder are composed of the mixture of uric acid dihydrate and ammonium acid urate.     

Biochemical relationship between urine composition and urinary stone formation in stone forming patients

The precise relationship between urine composition and stone formation has not yet been completely understood. The object of this work is to study some constituents of the urine in stone formers and normal subjects in a trial to correlate stone formation with urine composition. Urinary levels of oxalic acid, uric acid and phosphate were elevated in oxalate, urate and phosphate stone formers, respectively, while in the urine of mixed stone formers both oxalic and uric acids were increased. Urinary levels of ascorbic acid, citric acid and mucopolysaccharides in all groups of patients were significantly higher than the corresponding control levels. Although oxalic acid, uric acid and phosphate concentrations were high in their respective stones, the concentrations of these constituents were nearly the same in the mixed stones. Also Ca²⁺ concentration was higher in stones of oxalate and mixed stone formers than in stones of urate and phosphate formers. Exceptionally, magnesium was high in stones of phosphate stone formers. It is recommended that urinary contents of oxalate, urate and phosphate have to be minimized to overcome stone recurrence.     

Metabolic investigation of recurrent nephrolithiasis: compliance with recommendations

Objectives. Nephrolithiasis is a recurrent condition with significant associated morbidity and economic impact. Although urologic intervention addresses symptomatic stone episodes, prevention of recurrences with proven medical therapy is indicated.Methods. This retrospective study examined 97 patients who presented in 1997 and 1998 with recurrent nephrolithiasis in a large tertiary care center for the presence of an appropriate metabolic investigation as recommended by the National Institutes of Health Consensus Conference. Complete data were abstracted from the hospital and private clinic charts.Results. The average patient age was 50.5 years; 61.9% of patients were men. The mean number of stones per patient was 5.6 (range 2 to 62), with stone analysis performed for 78 patients. Fifty-eight stones (74.4%) were calcium oxalate and/or phosphate, 14 (17.9%) urate, 8 (10.3%) struvite, and 3 (3.8%) cystine. Five patients had two stone types on different occasions. Either lithotripsy or a urologic procedure was required for at least one stone presentation in 89 patients (91.8%). An investigation for stone disease was pending in 54 patients (55.7%). A complete evaluation, satisfying the preset criteria, was performed in 34 patients (35.1%). Six patients who did not undergo evaluation were lost to follow-up. Univariate analysis revealed that referral to a nephrologist (P = 0.001), treatment with medications used for stone disease (P = 0.008), and urate stones (P = 0.005) were associated with a complete investigation. Similarly, these were independently associated with a complete evaluation in regression analysis of 77 complete data sets, with odds ratios of 24.4 (nephrology referral), 4.9 (medication use), and 5.6 (urate stones).Conclusions. The results of this study demonstrate that a significant proportion of patients with recurrent nephrolithiasis do not undergo appropriate metabolic investigations. Efforts should be made to improve the evaluation of these patients.     

2015~2018年达州市尿路结石患者人口学特征及结石化学成分分析

目的对2015~2018年四川省达州地区尿路结石患者人口学特征及结石化学成分进行分析。方法选择2015年1月至2018年12月四川省达州市中西医结合医院进行治疗的583例尿路结石患者,经体外振动波碎石、手术、自排等方式获得结石标本583份进行研究。所有患者入组后均采集性别、年龄、居住地等一般资料,获取结石标本后以结石红外光谱自动分析系统对其化学成分进行分析。结果583例患者中单纯性结石289例(49.75%),二重混合性结石288例(49.40%),三重混合性结石6例(1.03%)。从结石成分分布上看草酸钙占比最高,为94.00%,其次是磷酸磷灰石37.04%、尿酸及尿酸铵14.92%。女性患者磷酸铵镁占比为4.31%,明显高于男性的1.35%(P<0.05)。其他成分不同性别患者分布情况差异无统计学意义(P>0.05)。60岁以下的患者结石成分为草酸钙占比为96.69%,明显高于60岁及以上者的89.55%(P<0.05)。其他成分不同年龄段患者分布情况差异无统计学意义(P>0.05)。城镇居民患者草酸钙、磷酸磷灰石占比分别为96.69%、40.38%,均明显高于农村居民的89.82%、28.74%(P<0.05)。其他成分不同居住环境患者分布情况差异无统计学意义(P>0.05)。结论四川达州地区尿路结石患者结石化学成分易草酸钙为主,其次为磷酸磷石灰石、尿酸及尿酸铵。不同性别、年龄、居住环境对尿路结石化学成分分布有一定的影响。     

306例膀胱结石成分及相关危险因素分析

目的探讨膀胱结石患者发病年龄、性别及结石成分的特点,为临床防治提供依据。方法采用傅立叶红外光谱压片法分析306例膀胱结石成分,按年龄每10岁一组划分,性别及化学成分列表作相关分析。结果 306例膀胱结石中224例是含钙结石（73.20%）,以草酸钙为主,其中单纯草酸钙72例（23.53%）;含磷酸盐161例（52.61%）;含尿酸盐115例（37.58%）,其中纯尿酸55例（17.98%）;单一成分结石127例（41.50%）,2种成分混合性结石107例（34.97%）,3种成分混合性结石72例（23.53%）,混合结石共179例（58.50%）。男性膀胱结石患者284例,占92.81%,50岁以上发病率占87.32%。结论膀胱结石成分以含钙结石、磷酸盐和尿酸盐为主,男性、高龄是膀胱结石患病的危险因素。     

The severity of infection stones compared to other stones in the upper urinary tract

A retrospective study of the case records of 391 adult patients with spontaneously passed or surgically removed concrements from the upper urinary tract during the period 1982-1983 was performed. According to chemical analysis, 66% of the stones were calcium stones, 30% were infection stones, 4% were uric acid/urate stones and 1% were cystine stones. Of the infection stones 12 (10%) were staghorn calculi. The infection stones placed a greater strain on the patients than the calcium stones. Thus, infection stones were significantly more often recurrent stones and required surgery significantly more often than the calcium stones. Only 6% of the patients with infection stones had proved abnormalities predisposing to upper urinary tract infection. Urinary tract infection with a urease-producing microorganism was detected in only 52% of the patients with infection stones. As infection with a urease-producing microorganism is a prerequisite for the formation of infection stones in the urinary tract a careful microbiological investigation to find and treat the infection responsible for the stone formation is mandatory.     

Treatment of radiolucent renal calculi using ESWL combined with urine alkalinization

During the last 16 months, out of a total of 50 patients with renal urate stones 30 were treated by ESWL alone (Group A) and 20 by ESWL combined with urine alkalinization (Group B) as an adjuvant treatment. The stones were single in 14 cases multiple in 25 and branching in 11 cases. the average long axis of the stones was 3.6 cm. In Group A 76.6% of the patients were stone-free 3 months after ESWL, in comparison with 90% in Group B patients who underwent the combined treatment.     

Percutaneous suprapubic cystolithotripsy for pediatric bladder stones in a developing country

OBJECTIVE: To evaluate our experience with percutaneous suprapubic cystolithotripsy (PCCL) in Yemeni children with endemic urinary bladder stones. PATIENTS AND METHODS: Between January 1993 and December 1998, 117 children underwent percutaneous suprapubic lithotripsy in Arabia Felix Modern Hospital, Sana'a Republic of Yemen. The patients' ages ranged from 8 months to 14 years (average 3.7 years). Ninety patients (77%) were under 5 years old; 20 patients (16%) were between 6 and 10 years old, and 7 patients (6%) were between 11 and 14 years old. There were 116 boys and 1 girl. The stone size ranged from 0.7 to 4 (average 2.3) cm. Five patients had coexisting urinary bilharziasis and another 5 patients had coexisting renal stone. In 10 patients, the stone was in the urethra. The procedure was done under general anesthesia. Dilation of the tract was made under fluoroscopy. The instrument was an adult 26-french nephroscope, the same as that used for percutaneous nephrolithotripsy. Ultrasound disintegration was needed for stones of > 1 cm. A suprapubic catheter was left for 24 h, and a urethral catheter was kept for 48 h. RESULTS: All patients became stone free. The average operating time was 15 (5-50) min. The average hospital stay was 2.7 (2-5) days. No severe intra- or postoperative complication was observed. The nucleus and/or the main component of the stones were ammonium acid urate in 109 patients (93%). CONCLUSION: Based on our experience we can conclude that percutaneous suprapubic lithotripsy is a safe and effective method for the treatment of bladder stones in children. It reduces morbidity and hospital stay and thus the cost of treatment. Our series proves the nutritional etiology of endemic pediatric bladder stones. To our knowledge, this is the largest series reported on percutaneous suprapubic management of endemic bladder stones in children.     

The aetiological and clinical pattern of childhood urolithiasis in Saudi Arabia

The clinical and aetiological pattern in 85 stone-forming children presenting to an integrated nephrourological service in Riyadh is reviewed. All patients were below the age of 15 years, the male to female ratio being 2∶1. Only 2 children presented with bladder calculi. The remaining all had upper tract stone and, in 12 cases, these were bilateral. Of 34 calculi recovered for analysis, one-third was predominantly calcium oxalate and a further third was composed of uric acid or urate. Four patients had cystine stones and the remaining 7 presented mixed calcium stones, 6 (17.6%) being struvite and infection-related. Of the 85 patients 55 were treated successfully with extracorporeal shock wave lithotripsy, 16 underwent surgery and 7 had their stones removed by endourological procedures. In the remaining 7 children, stones dissolved or were passed spontaneously during medical therapy. Nine children (10.6%) showed a primary metabolic defect leading to their stone formation, 10 (11.8%) had a predisposing anatomical anomaly and 15 (17.6%) presented with urinary tract infection. Of the remaining 51 patients (60%) with idiopathic disease, 6 showed hypercalciuria on investigation and 2 children may have formed their stones due to prolonged recumbency.     

Epidemiology and socioeconomic aspects of urolithiasis

Summary This epidemiologic study reveals that the occurrence of urolithiasis in the nineteenth century population in Europe is quite similar to that of the twentieth century in Asia. The analogy is demonstrated for age distribution, stone localization, male/female ratio, and stone composition. The distribution of urolithiasis in a low socioeconomic level population is defined by: highest frequency in childhood, more than 40% bladder stones, less than 20% female patients, less than 40% calcium-oxalate stones, and more than 30% uric acid/urate stones. Typical for a population with a high level these characteristics of urolithiasis are: highest frequency among adults, less than 10% bladder stones, more than 25% female patients, more than 60% calcium oxalate stones, and less than 20% uric acid/urate stones. In partially developed countries those values fall in between.     

A study of the etiology of idiopathic calcium urolithiasis in children: hypocitruria is the most important risk factor

PURPOSE: To determine the association of metabolic risk factors with pediatric calcium urolithiasis we compared metabolic evaluation data on children with idiopathic calcium stones and those on healthy children. MATERIALS AND METHODS: Metabolic evaluation was done in 78 calcium stone formers 1 to 15 years old (mean age 7.2) who were free of urinary tract infection, anatomical abnormalities, and metabolic, endocrinological and intestinal disorders, and in 24 healthy children. Evaluation included serum biochemistry, and measurement of daily excretion of urinary calcium, oxalate, urate, phosphorus, citrate and magnesium. RESULTS: Demographic characteristics, serum parameters, and daily excretion of calcium, urate, phosphorus and magnesium did not differ statistically in the 2 groups. However, urinary oxalate was significantly higher and urinary citrate was significantly lower in stone formers than in controls (p = 0.002 and 0.028, respectively). Hypocitruria and hyperoxaluria were 4.3 and 3-fold more common in stone formers than in controls, respectively. Multivariate analysis using logistic regression showed that hypocitruria was the only significant risk factor for idiopathic calcium stones (p = 0.008). CONCLUSIONS: Hypocitruria was the most important risk factor in our patients. Hyperoxaluria was also common and accompanied hypocitruria in many stone formers. In contrast to many previous reports, we failed to show that hypercalciuria is an important metabolic defect for idiopathic calcium stones, possibly because our study evaluated a different population.