Urolithiasis in pregnancy

Urolithiasis is the most common cause of urological-related abdominal pain in pregnant women after urinary tract infection. The disease is not uncommon during pregnancy occurring in 1/200 to 1/2,000 women, which is not different from the incidence reported in the nonpregnant female population of reproductive age. During pregnancy, the frequency of stone localization is twice as higher in the ureter than in the renal pelvis or calyx, but there is no difference between the left and right kidney or ureter. Urinary stones during pregnancy are composed mainly of calcium phosphate (hydroxyapatite) in 74% of cases and calcium oxalate in the remaining 26% (Ross et al., Urol Res 36:99–102, 2008). In conclusion, urolithiasis during pregnancy can be serious, causing preterm labor in up to 40% of affected women. The pathogenesis, diagnosis, and management are analyzed.     

Some data on urinary stones which were passed.

Out of a group of 979 patients with urinary calculi, 175 had passed their stone(s). Comparison of data for stones which had been passed with data for the whole group shows many significant differences. Calculi composed entirely of calcium oxalate are more likely to be expelled than any other composition variety. The chance of this happening is 1 in 3 and it is even higher when the person is under 50 years of age. The probability of calculi composed of calcium oxalate+calcium phosphate being expelled is 1 in 5 and this also increases for younger patients. Infection stones consisting of calcium phosphate+struvite have only 1 in 19 chance of being passed. Many of the stones passed (130) are under 0.10 g in weight. However, there is a similar relationshp between composition and weight among both the stones that were passed and the whole group. In both groups, pure oxalate stones are the lightest, infection stones are the heaviest and stones composed of calcium phosphate and calcium phosphate+calcium oxalate are of intermediate weight.     

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.     

Structural features of three ureterocele calculi

Ureterocele calculi are developed in cavities with urinary retention but far from the upper renal cavities. The structural features of three ureterocele calcium oxalate stones were observed by scanning electron microscope coupled with X ray microanalysis. The urinary parameters of the three patients were also determined. The stone A consisted of loose structure of large calcium oxalate dihydrate crystals and small spheres of hydroxyapatite. The interior contains disorganized plate-like calcium oxalate monohydrate crystals. The stone B was formed by a compact outer layer of calcium oxalate monohydrate columnar crystals. The structure of stone interior was similar to the stone A. The stone C was formed by concentric layers composed of either calcium oxalate monohydrate columnar crystals or hydroxyapatite. The core consisted of agglomerated calcium oxalate monohydrate crystals, hydroxyapatite and organic matter. From the urinary biochemical data it was deduced that two ureterocele patients (who formed A and B stones) were hypercalciuric (calcium > 300 mg/24 h), being 6.5 the urinary pH value of the patient that formed the A stone, and 7.0 the urinary pH of the patient that formed the C stone. The rest of urinary parameters for the three patients were normal. Thus, one of the requisite conditions for unattached stone development is the existence of a place inside the urinary tract where the solid particles that act as calculus initiator of the stone can be retained enough time to exert this action.     

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.     

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).     

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 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.     

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.     

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.     

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.     

非增强螺旋CT平扫对上尿路结石成分预测的体内研究

目的 探讨非增强螺旋CT对体内上尿路结石化学成分的预测价值.方法 回顾性分析156例有结石标本的上尿路结石患者临床资料.所有患者在治疗前采用GE High speed CT/i螺旋CT机行非增强结石扫描,扫描参数为120 kV,320 mA,螺距0.6:1,扫描层厚为5 mm.在CT软组织窗测量结石平均CT值.将获取的结石样本采用红外光谱自动分析系统进行化学成分定性分析.经统计学分析,找出各种成分结石的相应CT值范围.结果 非增强螺旋CT扫描156例结石的软组织窗CT值范围为128～ 1663亨氏单位(hounsfield unit,HU).共发现纯结石57例,其中纯一水草酸钙结石28例,纯尿酸结石19例,纯羟基磷灰石10例,混合结石99例.一水草酸钙、尿酸、羟基磷灰石三种纯结石的软组织窗平均CT值分别为(915.4±142.9) HU、(469.7±55.1) HU、(868.4±168.8)HU.尿酸结石与一水草酸钙结石、尿酸结石与羟基磷灰石之间的CT值差异有统计学意义(P＜0.05).19例纯尿酸结石和137例其他成分结石的软组织窗平均CT值之间差异有统计学意义(P＜0.05).以结石的软组织窗平均CT值＜ 550 HU为标准诊断纯尿酸结石,其灵敏度为92.8％,特异度为98.1％,阳性预测值为88.5％,阴性预测值为99％,诊断符合率为98.1％.结论 非增强螺旋CT平扫用于判断上尿路结石成分效果满意.根据软组织窗CT值不同,可将体内尿酸结石与其他成分结石区分.软组织窗平均CT值＜550 HU可作为纯尿酸结石的诊断标准.     

螺旋CT扫描预测上尿路结石成分的体内研究

目的:研究螺旋CT对体内上尿路结石化学成分的预测价值。方法:2005年12月～2007年9月对157例上尿路结石患者在治疗前行螺旋CT平扫,测结石CT值。定量分析各种治疗方法所获取结石的化学成分。经统计学分析,找出不同成分结石的CT值范围。结果:一水草酸钙、尿酸、羟基磷灰石三种纯结石的软组织窗平均CT值分别为(851.50±188.74)HU、(446.92±47.20)HU和(835.53±110.58)HU。尿酸结石与一水草酸钙结石、尿酸结石与羟基磷灰石之间CT值的差异均有统计学意义。13例纯尿酸结石与144例尿酸含量小于70%的其他结石的CT值差异有统计学意义。以结石的软组织窗平均CT值500 HU为标准鉴别纯尿酸结石,其灵敏度为92.31%,特异度为96.53%,阳性预测值为70.59%,阴性预测值为99.29%。结论:结石的CT值可作为鉴别尿酸结石的一种方法,CT值小于500 HU的结石多考虑为尿酸结石。     

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。     

Comparison of urinary tract infection in calcium oxalate and calcium phosphate stone formers

To compare the frequency of urine infection in calcium oxalate and calcium phosphate stone formers, we reviewed charts from patients whose last renal stone submitted for analysis was predominantly composed of calcium phosphate in 118 and of calcium oxalate in 223. Positive cultures were commoner, but not significantly, in the phosphate than the oxalate stone formers, both in men (17 vs. 7.6%) and women (22 vs. 15%). Bacteria frequently producing urease were found in only 4% of the phosphate group. Urine leucocytes were slightly more frequent in the oxalate group for men and significantly so for women. The results do not support the concept that calcium phosphate stones are mainly due to infection with urease-producing or other bacteria.     

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。     

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.     

Gestational hypercalciuria causes pathological urine calcium oxalate supersaturations

Although normal pregnant women are more hypercalciuric than women with calcium oxalate nephrolithiasis (243 +/- 23 mg/day vs. 194 +/- 5 mg/day), pregnancy is not an established stone-forming state and pregnant women do not exhibit pathological crystalluria. One hypothesis to explain their lack of overt stone formation and pathological crystalluria is that pregnancy does not raise urine supersaturation with respect to stone forming salts such as calcium oxalate or calcium monohydrogen phosphate (brushite) to levels as high as in stone forming women. To test this hypothesis, we studied eleven normal women during each trimester of pregnancy, and between six and eight weeks post-partum. During pregnancy, hypercalciuria occurs with unchanged urine volume, citrate and magnesium excretions do not increase proportionally with calcium excretion, and urine pH increases. Supersaturations with respect to calcium oxalate (CaOx) and brushite (Br) are as high as those of women with calcium nephrolithiasis. The lack of pathological crystalluria and stones during pregnancy is not due to a failure of supersaturations to increase; urinary potential for crystallization is as high as in patients with established stone disease.