Analysis of spontaneously passed urinary tract stones

Most studies on epidemiology, composition, and recurrence of renal calculi include both spontaneously passed calculi and those retrieved after surgical manipulation or shock wave lithotripsy. The present study exclusively focused on epidemiology, composition, and recurrence of spontaneously expelled stones in patients from North and East Mallorca (Spain) which represents a geographically specific non-urban region of a developed country. The study involved 136 patients who spontaneously passed 205 renal calculi. All calculi were classified and sub-classified according to composition after macroscopic and microscopic examination. We also analyzed prevalence, gender, age, and stone recurrence rate over a period of 3 years. The peak incidence of spontaneously stone passage is within the fourth to sixth decade. Overall male to female ratio was 3/1. Calcium oxalate was the most prevalent composition (64.8%) followed by uric acid (25.3%), mixed stones (5.3%) and calcium phosphate calculi (4.3%). Uric acid stones were the most recurrent (50%) followed by calcium oxalate monohydrate papillary calculi (26.4%), calcium oxalate monohydrate un-attached calculi (19.2%), calcium oxalate dihydrate calculi (18.3%), calcium phosphate calculi (14%), and mixed calculi (12.5%). In conclusion, spontaneously passed stones in Mallorcan population have similar epidemiology, composition, and recurrence rate from that found in other developed countries. Calcium oxalate stones are largely the most spontaneously passed type of calculi and uric acid stones are the most frequently recurred. These findings are also found to be similar to those reported in previous studies examining both spontaneously and non-spontaneously passed stones.     

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.     

复杂性肾结石化学成分分析(附84例报告)

目的 :分析复杂性肾结石化学成分特点 ,为预防其复发提供依据。方法 :对 84例在我院行微经皮肾镜取石术的复杂性肾结石患者 (纳入标准为鹿角形结石、单肾或双肾多发性结石且最大结石直径 >2 .5cm)进行结石化学成分分析 ,同时收集相关临床资料。结果 :80例 (95 .2 % )为含钙混合性结石和感染结石 ,其中草酸钙加磷酸钙 30例 (35 .7% ) ;草酸钙加尿酸 14例 (16 .7% ) ;草酸钙加磷酸钙加尿酸 10例 (11.9% ) ,草酸钙加磷酸钙加胱氮酸 1例 ;含钙结石并发感染结石 14例 (16 .7% ) ;感染结石 11例 (13.1% )。 4例 (4 .8% )为单一成分。结论 :体积较大的复杂性肾结石成分复杂 ,生长过程中常多种病因参与 ,应加强其病因诊断和针对多种病因采用积极的预防性治疗     

Analysis of urinary calculi formed by Nigerians

50 stones formed by Nigerians were analysed using a combination of qualitative chemical analysis, and petrographic analysis with the Reichert Model NR 333 254, polarization microscope. The Bausch and Lomb binocular dissecting microscope was used for macroscopic examination of the specimens and for taking samples from the 'nucleus', inner and outer surfaces of the stones, for analysis. The results showed that calcium phosphate and magnesium ammonium phosphate accounted for 64% of the stones, calcium oxalate for 28% while uric acid accounted for 8%. This is in contrast to modern times Caucasian stones which are predominantly calcium oxalate. There appears to be a greater tendency for Nigerians to form large staghorn calculi than small stones that can passed spontaneously. The phosphate stones are known to be related to infection in the urinary tract. The findings on the composition of these calculi correlate with the previous findings of a high incidence of obstruction and infection in Nigerian patients with urinary calculi.     

Kidney stones during pregnancy: an investigation into stone composition

Kidney stones can be a source of considerable morbidity for pregnant women. Although there is a body of literature confirming that different stone compositions predominate for different age and sex cohorts, there have been no similar reports characterizing the nature of stone disease during pregnancy. We performed a multi-institutional study to define the composition of renal calculi diagnosed during pregnancy. We retrospectively reviewed the records from two stone referral centers of all patients diagnosed with a de novo kidney stone during pregnancy who underwent a procedure for the purpose of stone removal from June 2001 through September 2007. A total of 27 patients were identified, with a mean age of 26.8 years (range, 21-34). Twenty patients (74%) had no history of prior stone formation. Seven patients (26%) had previously formed stones, although none of these patients had a known kidney stone at the time they became pregnant. Stones were removed in the first, second, third trimester and immediately post-partum in 4, 52, 22, and 22% respectively. Stone removal was performed without complication in all cases. Analysis found that in 74% of all cases (20 patients) stones were composed predominantly of calcium phosphate (hydroxyapatite). In 26% of cases, (7 patients) the stones were composed predominantly of calcium oxalate. Of the seven patients with prior stone history, three patients had previously formed calcium phosphate stones and four patients had previously formed calcium oxalate stones. Calcium oxalate calculi are the most common stone in non-pregnant women of a comparable age as our subjects. However, our present data suggest that stones detected during pregnancy are most commonly composed of calcium phosphate (hydroxyapatite). Indeed, it is the minority of stones that are composed of calcium oxalate. Although the reason for this unusual preponderance of calcium phosphate calculi is unclear, physiologic alterations that occur during pregnancy may be influential.     

SEQUENTIAL ANALYSIS OF RECURRENT CALCIUM CALCULI BY INFRARED SPECTROSCOPY

Background: While the incidence of calcium urolithiasis increases, the precise mechanism of calcium oxalate stone formation is still controversial. Is the composition of a recurrent calcium oxalate stones always the same as previous ones? There are few reports that specifically address the question by study of sequential changes of the composition of recurrent calcium calculi. Method: From our medical records 70 patients with a history of two or more recurrent episodes of calcium oxalate stone disease were selected and the analyses of 190 stones were reviewed. Infrared spectroscopic analysis was done using a Perkin Elmer 1740 spectrophotometer. Results: Calcium oxalate monohydrate were detected in 63 stones, calcium oxalate dihydrate in 12, calcium oxalate monohydrate mixed with dihydrate in 28, calcium oxalate monohydrate mixed with calcium phosphate in 30, calcium oxalate dihydrate mixed with calcium phosphate in 20, calcium oxalate monohydrate mixed with dihydrate and calcium phosphate in 20, calcium oxalate monohydrate mixed with dihydrate and calcium phosphate in 37. Alterations of stone components during follow-up were found in 43 stones from 40 patients. The shift of a main composition from calcium oxalate monohydrate to calcium oxalate dihydrate was found in 24 stones and vice versa in 19 stones. Conclusions: Sequential changes of the compositions of recurrent calcium calculi are highly likely to occur with time in individual recurrent calcium stone formers. Calcium oxalate monohydrate was a most common component of the studied recurrent calcium stones.     

232例湖北地区泌尿系结石红外光谱成分分析

目的：分析湖北地区泌尿系结石化学成分的构成,为本地区结石的防治提供依据。方法：采用结石红外光谱自动分析系统对2011年11月～2012年8月期间收集到的湖北地区泌尿系结石232例进行成分分析。结果：232例结石中,各成分的检出率为：一水草酸钙（COM）85．34％,二水草酸钙（COD）62．93％,碳酸磷灰石（CA）24．14％,无水尿酸（UA）12．93％,二水磷酸氢钙（PH）4．31％,磷酸铵镁（MAP）6．90％,黄嘌呤1．29％,胱氨酸（CYS）1．29％,方解石0．86％,尿酸铵（AU）0．86％。含草酸钙成分结石86．21％,含磷酸钙成分结石28．45％,含磷酸铵镁成分结石6．90％,含尿酸成分结石13．79％,含胱氨酸成分结石1．29％。混合成分结石181例（78．02％）,尿路结石发病男性多于女性,男女比例为3．14：1。结论：湖北地区泌尿系结石以混合性结石为主,COM检出率最高,其次为COD。结石成分分析对于结石的防治有重要意义。     

The kidney-ureter stone sexual paradox: a possible explanation

The greater frequency of renal stones seen on excretory urograms in women, compared with the greater frequency of ureteral stones in men has been termed a sexual paradox. We assessed stone composition and weight, and sex as possible explanatory factors. A total of 4,014 renal and ureteral calculi was analyzed. For the 3,119 calculi in which only calcium oxalate and/or phosphate was detected by infrared and wet chemical analysis, there was a strong relationship between the oxalate-to-phosphate weight ratio and sex (p less than 0.0001). The mean weight for phosphate stones was 330 mg. but for oxalate stones it was 107 mg. Male-to-female ratios were 2.7, 2.2 and 1.8 for stone weight groups of 20 or less, 21 to 100 and more than 100 mg. The male-to-female ratio was 0.87 for the 171 stones containing magnesium ammonium phosphate; the average weight was 508 mg. for men and 1,560 mg. for women. The tendency for phosphate stones to be heavier and relatively more common in women compared to predominantly oxalate stones may partly account for the sexual paradox.     

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.     

The role of hyperoxaluria in the formation of calcium oxalate urinary calculi, and its association with other biochemical measurements

The part played by hyperoxaluria in the formation of calcium oxalate urinary calculi was studied in 153 patients who had each been diagnosed as having calcium oxalate urinary calculi on one or more occasions. Seventy-seven of the patients excreted normal amounts of calcium (less than 6.2 mmol/d), and 76 had hypercalciuria (excretion greater than or equal to 6.2 mmol/d); each group was divided into a further two groups depending on whether the oxalate concentration was above or below 0.16 mmol/l. Pure calcium oxalate stones were more common in patients whose calcium excretion was normal, and mixed calcium oxalate and phosphate stones were more common among hypercalciuric patients. Urinary concentrations/day of magnesium, citrate, and phosphorus were significantly lower in the two groups in which the oxalate concentrations were below 0.16 mmol/l than in a normal control group, and magnesium and phosphorus were significantly lower in the two groups in which oxalate concentrations were less than 0.16 mmol/l than in the two in which they were above that value. The concentration of citrate was also lower, but not significantly so. In addition, the pH of the urine in patients with mixed stones was significantly higher in all groups than when the stones were composed of pure calcium oxalate.     

Clinical patterns of paediatric urolithiasis

A series of 270 paediatric stone patients was studied retrospectively according to the clinical pattern of urolithiasis (age and sex, stone location, stone analysis, recurrence rate) and aetiology of stone disease (infection, anatomical, metabolic or idiopathic). Infection stones occurred earliest and more commonly in males and were usually upper tract struvite calculi related to Proteus infection. Anatomical stones were most commonly associated with pelviureteric junction (PUJ) obstruction and had a high recurrence rate, despite surgical correction of obstruction. Idiopathic stones most resembled those found in adult urolithiasis by virtue of occurring latest, being sited in the ureter more often and being more frequently composed of calcium oxalate. Metabolic stones were most frequently calcium phosphate or cystine and virtually all were renal. They comprised the smallest group but had the highest recurrence rate.     

Spectrum of stone composition: structural analysis of 1050 upper urinary tract calculi from northern India

BACKGROUND: The purpose of the present paper was to study the spectrum of stone composition of upper urinary tract calculi by X-ray diffraction crystallography technique, in patients managed at All India Institute of Medical Sciences. METHODS: Between 30 April 1998 and 31 March 2003, a total of 1050 urinary calculi (900 renal, 150 ureteric) were analyzed. The stone fragments were collected after extracorporeal shock-wave lithotripsy, or retrieval by endoscopic (percutaneous nephrolithotomy, ureterorenoscopy), laparoscopic and various open surgical procedures. The structural analysis of the stones was done using X-ray diffraction crystallography. RESULTS: Four types of primary and three secondary X-ray diffraction patterns were obtained. The primary patterns were as follows. Pattern A, well organized crystalline structure; pattern B, moderately organized crystalline structure; pattern C, poorly organized crystalline structure; pattern D, very poorly organized crystalline structure. The three secondary patterns mainly highlighted the mixed variety of stones. These patterns were further analyzed and compared with standard X-ray diffraction (powder) photographs. Of the 1050 stones analyzed, 977 (93.04%) were calcium oxalate stones, out of which 80% were calcium oxalate monohydrate (COM) and 20% were calcium oxalate dihydrate (COD). Fifteen were struvite (1.42%) and 19 were apatite (1.80%). Ten were uric acid stones (0.95%) and the remaining 29 (2.76%) were mixed stones (COM + COD and calcium oxalate + uric acid, calcium oxalate + calcium phosphate, and calcium phosphate + magnesium ammonium phosphate). A total of 89.98% of staghorn stones were made of oxalates (COM/+COD) and only 4.02% were struvite. CONCLUSION: Urinary stone disease in the Indian population is different from that in Western countries, with a larger percentage of patients having calcium oxalate stones, predominantly COM. Also, the majority of staghorn stones (89.98%) were made of oxalates.     

The characteristics of urolithiasis in East Thrace: A statistical review

During a 6-year period 390 patients with urinary tract calculus were studied: 293 had upper and 38 had lower urinary tract calculi. Of these, 59 passed their stones spontaneously on conservative therapy, 294 were treated surgically and 37 stones were removed by endoscopic means. Of the patients 10.54% had a history of urolithiasis, 5.34% reported family history. In contrast, to the common belief, the highest admission rate was in winter. The male to female ratio was found to be 2.2: 1, whereas it was equal (1∶1) in childhood. The peak incidence was between the ages 30 and 39. Urinary tract infection and obstruction of varying severity were the common coexisting abnormalities. Calcium was the main component of both the upper and lower tract stones. Calcium oxalate+phosphate and calcium oxalate+struvite were the most common mixed stones. Blood typing did not reveal any specificity for urinary calculous disease. On the other hand, occupational groups leading a sedentary life were more prone to this malady.     

Difference in urinary stone components between obese and non-obese patients

The prevalence and incidence of urinary stone disease have been reported to be associated with body weight and body mass index (BMI). The aim of the study was to determine the difference in stone components among different BMI groups in patients with urolithiasis. Between Dec 2005 and Jan 2008, 907 urinary calculi were collected and analyzed by infrared spectroscopy. Most of the stones had been passed spontaneously, and some were collected during surgical manipulations. The data on patients’ gender, age, BMI at diagnosis, and stone composition were collected. The patients were classified as normal weight (18.5≤ BMI <24), overweight (24≤ BMI <27), or obese (BMI ≥27). Of the 907 patients with urinary stone disease, 27.7% had normal weight, 33.5% were overweight, and 38.8% were obese. The prevalence of calcium oxalate stones in the normal weight, overweight, and obese groups were 23.1, 30.6, and 34.9%, respectively (P = 0.002), and the prevalence of uric acid stones in the different groups was 2.8, 7.2, and 7.7%, respectively (P = 0.002). The prevalence of calcium oxalate and uric acid stones, but not that of calcium phosphate stones, increased with body size. There was a significant correlation between BMI and uric acid stones in the overweight and obesity groups, with odds ratios of 3.28 and 4.35, respectively. The prevalence and incidence of urinary stone disease were found to be associated with BMI. The percentage of uric acid and calcium oxalate stones was higher in obese than in non-obese patients. There was no apparent difference in the prevalence of calcium phosphate stones between obese and non-obese patients.     

Determination of stone composition by noncontrast spiral computed tomography in the clinical setting

OBJECTIVES: Several investigators have evaluated noncontrast computed tomography (NCCT) in predicting stone composition in vitro. We assessed NCCT in predicting stone composition in patients presenting to our emergency room with flank pain and stone disease. METHODS: One hundred twenty-nine patients presenting to our university hospital with flank pain underwent renal colic protocol NCCT scans at the request of the emergency room physicians. A General Electric, high-speed advantage CT scanner was used at 120 kV, 200 mA, and 1.4:1 pitch, with collimation varying between 3 and 5 mm. Ninety-nine patients with predominantly (greater than 50%) calcium oxalate or uric acid composition after either stone passage or stone removal were identified. Each scan was analyzed by one of two radiologists, who determined the predominant attenuation for each stone. Stones once passed or retrieved were analyzed by Urocor Laboratories. The attenuation and attenuation/size ratio (peak attenuation/size in millimeters) were compared with the results of the stone analysis. RESULTS: Eighty-two calculi predominantly composed of calcium oxalate and 17 calculi predominantly composed of uric acid were identified in 99 patients. The calculi ranged in size from 1 to 28 mm. A significant difference (P = 0.017, unpaired t test) was found between the Hounsfield measurement of uric acid calculi (mean 344 +/- 152 HU) and the Hounsfield measurement of calcium oxalate calculi (mean 652 +/- 490 HU). If only the Hounsfield units from stones 4 mm or larger were compared, the data were even more compelling (P = 0.002). However, using an attenuation/size ratio cutoff of greater than 80, the negative predictive value was 99% that a stone would be predominantly calcium oxalate. CONCLUSIONS: Using peak attenuation measurements and the attenuation/size ratio of urinary calculi from NCCT, we were able to differentiate between uric acid and calcium oxalate stones.     

Relationship of frequency, age, sex, stone weight and composition in 15,624 stones: comparison of resutls for 1980 to 1983 and 1995 to 1998

PURPOSE: We studied the relationship of stone frequency and composition to age, sex and stone weight. MATERIALS AND METHODS: A retrospective study was performed of all 15,624 stones submitted for analysis with infrared and wet chemical methods in Newfoundland and Labrador from 1979 to 1998. RESULTS: There were 1,067 bladder stones of which 216 contained magnesium ammonium phosphate. The remaining 14,557 stones were from the kidney and ureter, and 11,707 were composed only of calcium oxalate and/or phosphate. Of the remaining 2,850 kidney and ureter stones magnesium ammonium phosphate was present in 573, uric acid/urate without magnesium ammonium phosphate in 1,109 and other compounds in 1,168. The 11,707 oxalate phosphate group was subdivided by infrared peak analysis based on oxalate-to-phosphate ratio into phosphate-ratio 1 or less, intermediate-1 to 10 and oxalate-10+. Oxalate comprised 65% of the 11,707 stones compared to 16% for phosphate. Women submitted 52% of phosphate stones compared with 28% of oxalate stones. From the first (1980 to 1983) to the last (1995 to 1998) complete 4-year study periods, there was a relative increase in oxalate and decrease in phosphate stones, associated with increasing age from decades 5 to 6 for oxalate and phosphate stones, except that the age peak for phosphate stones in women remained in decade 3. Median weight of 1, 828 phosphate stones was 43 mg. (mean 234) compared with 25 mg. (mean 98) for 7,634 oxalate stones. Male-to-female ratio was 0.91 for phosphate stones compared with 2.62 for oxalate stones. CONCLUSIONS: Phosphate stones were on average heavier and relatively more common in women, had an earlier age peak frequency in women than oxalate stones and became less frequent during our last 4-year study period. In contrast, oxalate stones were much more common, of lighter weight and became more frequent with time.     

Evaluation of chemical composition of urinary calculi by conventional radiography

BACKGROUND AND PURPOSE: The choice of the most efficient treatment modality for renal calculi could be facilitated by determining the precise chemical stone composition before treatment. We investigated the possibility of using conventional X-ray imaging to determine stone composition and to find a simple method of predicting stone fragility for treatment planning. MATERIALS AND METHODS: The X-ray density of 92 stones with known infrared spectroscopy analyses (calcium oxalate monohydrate, calcium oxalate dihydrate, struvite, and calcium phosphate) was retrospectively investigated by scanning the films with a digital camera. The data analysis was done using a commercially available graphics program to compare the total gray-scale levels of the stones. RESULTS: There was a significant difference in the mean gray-scale level of calcium phosphate and calcium oxalate stones (P < 0.01). The mean gray-scale difference between calcium oxalate dihydrate and calcium oxalate monohydrate was also significant (p < 0.02). All calcium oxalate, struvite, and calcium phosphate stones were correctly identified. Of the calcium oxalate monohydrate and calcium oxalate dihydrate stones, 98.4% and 66.6%, respectively, were correctly identified. CONCLUSION: The method allows a reliable diagnosis of stone composition from radiographs, which can be useful in stone treatment planning.     

Bacteriology of upper urinary tract stones

Extensive cultures of stones and urine were performed in 215 patients who underwent an operation for upper urinary tract calculi. Microorganisms could be cultured from the stone in 1 of every 3 patients. Despite the extended culture technique urease-producing microorganisms could be cultured from the stone in only 48% of the patients with calculi that contained magnesium ammonium phosphate. This finding suggests that an infection with urease-producing microorganisms is not obligatory for the formation of this type of stone. Of the patients with calcium oxalate phosphate stones 32% had positive stone cultures, which distinguished them from patients with pure calcium oxalate stones, only 8% of whom had a positive stone culture (p less than 0.001).     

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.     

Composition of urinary tract calculi from some developing countries.

The composition of 142 calculi from Sudan, Thailand, Indonesia and Saudi Arabia has been determined by qualitative and quantitative chemical analysis. Calcium oxalate was the commonest constituent of both kidney and bladder stones, followed by magnesium ammonium phosphate, ammonium acid urate, calcium phosphate, uric acid and cystine in that order. Calcium oxalate was also the main constituent of the nucleus of most kidney and bladder stones, calcium phosphate, magnesium ammonium phosphate, and ammonium acid urate occurring most frequently in the outer layers of the stones. Most endemic bladder stones appear to originate as aggregates of calcium oxalate crystals in the kidney, which subsequently descend to the bladder, where they may acquire secondary deposits of calcium phosphate, magnesium ammonium phosphate or ammonium acid urate.