Influence of indwelling urinary tract stones on twenty-four-hour urine chemistries

Twenty-two patients with ureteral stones underwent twenty-four-hour urinary excretion studies of calcium, phosphorus, and uric acid before and after stone elimination from the urinary tract. Comparison of pre- and post-stone elimination studies showed no significant differences suggesting that the presence of stones in the urinary tract has little influence on the twenty-our-hour urinary excretion of calcium, phosphorus, and uric acid.     

Physicochemical metabolic characteristics for calcium oxalate stone formation in patients with gouty diathesis

PURPOSE: We determined why calcium oxalate stones instead of uric acid stones form in some patients with gouty diathesis. MATERIALS AND METHODS: Gouty diathesis was diagnosed from absence of secondary causes of uric acid stones or low urinary pH, and reduced fractional excretion of urate with discriminant score of the relationship between urinary pH and fractional excretion of urate less than 80. From the stone registry 163 patients with gouty diathesis were identified, including 62 with uric acid stones (GD + UA) and 101 patients with calcium oxalate stones (GD + Ca). Metabolic data and 24-hour urinary chemistry study were compared between the 2 groups. RESULTS: Compared with GD + UA, GD + Ca had significantly greater urinary calcium (196 +/- 96 mg per day vs 162 +/- 82 mg per day, p <0.05) and significantly lower urinary citrate (430 +/- 228 vs 519 +/- 288 mg per day, p <0.05), resulting in higher urinary saturation of calcium oxalate. Both groups had low urinary pH (less than 5.5) and high urinary undissociated uric acid (greater than 100 mg/dl). Urinary calcium post-oral calcium load was significantly higher in GD + Ca than in GD + UA (0.227 vs 0.168 mg/dl glomerular filtrate, p <0.001). CONCLUSIONS: Calcium oxalate stones may form in some patients with gouty diathesis due to increased urinary excretion of calcium and reduced excretion of citrate. Relative hypercalciuria in GD + Ca may be due to intestinal hyperabsorption of calcium.     

上尿路结石复发原因分析及其治疗(附42例报告)

目的:探讨泌尿系结石复发的原因及其处理措施。方法:回顾性分析2005年1月～2010年5月在我院接受治疗的42例上尿路复发结石患者临床资料,并对其尿石成分进行分析,对血、尿理化指标及代谢指标进行检测。结果:术后复发结石成分中,与原发结石成分相同者34例;与原发结石成分不同者8例,其中1例为尿流改道术后(草酸钙结石变为尿酸结石),1例为ESWL术后(草酸钙结石变为尿酸结石),3例为开放取石术后(草酸钙结石变为感染结石及尿酸结石),2例为输尿管碎石取石术后(尿酸结石变为感染结石)。在血、尿理化检测中,糖尿病8例,尿路感染7例,肥胖6例,甲状旁腺机能亢进3例。结论:根据复发性尿路结石的临床特点及诱发因素,采取针对性措施,选择合理的治疗方式,可以提高治疗效果。     

Can the manipulation of urinary pH by beverages assist with the prevention of stone recurrence?

The formation of various types of stones in the urinary tract is strongly influenced by urinary pH. An acidic urinary pH promotes the crystallization of uric acid and cystine, respectively. Moreover, changes in systemic acid–base homeostasis alter urinary excretion of citrate, an important inhibitor of calcium oxalate stone formation. The effect of beverages on urinary pH and citrate excretion is mainly determined by the presence of bicarbonate and citrate. The bicarbonate content of mineral water can replace alkalization therapy with potassium citrate and contribute to urine inhibitory power by increasing urinary pH and citrate excretion. Citrus juices are rich sources of citrate. Oral citrate is absorbed in the intestine and nearly completely metabolized to bicarbonate, providing an alkali load, which in turn increases urinary pH and citrate excretion. However, data from observational and interventional studies on the effect of different types of citrus juices on the risk of urinary stone formation are conflicting. In conclusion, favourable changes in urinary pH and citrate excretion can be attained by various beverages. However, the long-term efficacy of certain beverages for the recurrence prevention of different types of stones has yet to be determined.     

The composition of urinary stones in the Sudan

Seventy-eight urinary stones from the Sudan were analysed quantitatively; 75.6% of upper urinary tract (UUT) stones and 37.8% of lower tract (LUT) stones were composed of pure calcium oxalate monohydrate. The composition of adult UUT stones in the Sudan is almost identical to that of similar stones from Leeds except that the former contain much more calcium oxalate and much less calcium phosphate. A smaller proportion of adult LUT stones from the Sudan contain magnesium ammonium phosphate and a larger proportion contain uric acid/urate than similar stones from Leeds. Juvenile LUT stones from the Sudan probably contain more calcium oxalate and less uric acid/urate than juvenile bladder stones in some other developing countries.     

Pathophysiologic basis for normouricosuric uric acid nephrolithiasis

BACKGROUND: Low urinary pH is the commonest and by far the most important factor in uric acid nephrolithiasis but the reason(s) for this defect is (are) unknown. Patients with uric acid nephrolithaisis have normal acid-base parameters according conventional clinical tests. METHODS: We studied steady-state plasma and urinary parameters of acid-base balance in subjects with normouricosuric pure uric acid stones. We also tested the ability of these subjects to excrete ammonium in response to an acute acid load. We compared these parameters in patients with pure uric acid stones to patients with mixed uric acid/calcium oxalate stones, pure calcium stones, and normal volunteers. RESULTS: Pure uric acid stone formers have a much higher incidence of either diabetes or glucose intolerance. After equilibration to a control diet, patients with uric acid stones have lower urinary pH and they excrete less of their acid as ammonium. This is compensated by higher titratable acidity and hypocitraturia. Despite their low baseline urinary pH, uric acid stone formers further acidify their urine after an acid load because of a severely impaired ammonia excretory response. Their characteristics are significantly different from normal volunteers and pure calcium stone formers. Patients with mixed uric acid/calcium stones exhibit intermediate characteristics. CONCLUSION: We propose that certain patients with normouricosuric uric acid nephrolithiasis have a renal acidification disease. The primary defect lies in renal ammonium excretion, which may be linked to the insulin-resistant state. Although net acid excretion is maintained at the expense of increased titratable acidity and to some degree hypocitraturia, the compromise is acid urine pH and may result in uric acid nephrolithiasis.     

Role of the urinary calcium in the growth of calcium stone

We analyzed the relationship between the rate and clinical factors. The growth rate per year of the stone was measured by Nabeshima's method in 29 male patients with renal calcium stones including 7 pure calcium oxalate (CaOx) stones and 22 mixed calcium oxalate and calcium phosphate (CaOx-CaP) stones. The 24-hour urinary excretion of calcium, phosphate, uric acid and magnesium were assayed under an ambulatory free diet in 5 patients with CaOx stones and 15 with CaOx-CaP stones. The relationship between the growth rate and the urinary excretion of stone-forming parameters was examined. We found a significant positive correlation between the growth rate of calcium stones and the urinary excretion of calcium (p<0.02). In addition, the growth rate of CaOx-CaP stone was significantly higher than that of pure CaOx stone (p<0.05). In conclusion, urinary calcium is important for the growth of renal calcium 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.     

Metabolic syndrome and nephrolithiasis

Recent epidemiological studies revealed an association of obesity, diabetes mellitus, hypertension and metabolic syndrome (MetS) with kidney stone disease. We examined how these disorders cause kidney stones. A clinical study on 467 patients with nephrolithiasis at our institution revealed that clustering of MetS traits increased the risk of uric acid stone formation by decreasing urinary pH. A subsequent study analyzing detailed data from 30,448 patients enrolled in the 6th Nationwide Survey on Urolithiasis in Japan showed that clustering of MetS traits were associated with an increased severity of the kidney stone disease and elevated urinary excretion of calcium, uric acid and oxalate. Finally, the OLETF rats, an animal model of MetS, showed lower urinary pH, decreased citrate excretion, and increased uric acid and calcium excretion. In addition, the administration of pioglitazone, an agent that improves insulin resistance, significantly increased the urinary pH. These results indicate that MetS causes changes in urinary constituents, leading to an increased risk of both uric acid and calcium oxalate stone formation. We suggest that kidney stone disease should be considered as a component of MetS and that the improvement in insulin resistance by means of diet and lifestyle changes and medical therapy might help to prevent this disorder.     

Effect of ethyl icosapentate on urinary calcium and oxalate excretion

BACKGROUND: The effect of ethyl icosapentate (EPA-E) on urinary calcium and oxalic acid excretion was examined to evaluate whether EPA-E is useful in the prevention of calcium-containing urinary stones. METHODS: For 6 months, urine was measured daily from 40 calcium-containing urinary stone producers at an outpatient clinic, before and after the administration of 1800 mg/day EPA-E. The urine was measured for volume, urea nitrogen, creatinine, calcium, magnesium, phosphorus, uric acid, oxalic acid and citric acid. Serum total cholesterol and triglyceride were also measured. RESULTS: Urinary calcium excretion was not reduced in any of the patients or particular hypercalciuric groups, nor did the level of calcium change. However, nine of the 25 hypercalciuric patients experienced a significant urinary calcium reduction to the normal calciuric level (a reduction of approximately 44%). It is not known why these particular patients experienced a reduction. Urinary oxalic acid did not change, whether hypercalciuria was present or not. CONCLUSIONS: These findings suggest that EPA-E is not particularly effective in reducing urinary calcium excretion in the hypercalciuric patients, but it needs future investigation because some patients experienced significant urinary calcium reduction.     

Risk factors for urolithiasis in children on the ketogenic diet

Kidney stones have been associated with use of the ketogenic diet in children with refractory seizure disorders. We performed a case-control study examining risk factors for the development of stones on the ketogenic diet, and prospectively followed children initiating the ketogenic diet to evaluate the incidence of urolithiasis. Clinical characteristics of 18 children presenting with stones (8 uric acid stones, 6 mixed calcium/uric acid stones, 1 calcium oxalate/phosphate stone, 3 stones not evaluated) were compared with characteristics of non-stone-forming children initiating the ketogenic diet at Johns Hopkins since July 1996. Since July 1996, 112 children initiating the ketogenic diet have been followed for development of stones. Follow-up times on the diet range from 2 months to 2.5 years. Of 112 children, 6 have developed stones (3 uric acid, 3 mixed calcium/uric acid stones) (0.8 children developing stones/ 100 patient-months at risk). Comparisons of children presenting with stones on the ketogenic diet with characteristics of the entire cohort initiating the ketogenic diet suggest younger age at diet initiation and hypercalciuria are risk factors for the development of stones. Prospective evaluation of children initiating the ketogenic diet revealed that almost 40% of patients had elevated fasting urine calcium: creatinine ratios at baseline; this increased to 75% after 6 months on the diet. Median urine pH was 5.5 at diet initiation, and remained at 6.0 thereafter. In a subset of patients tested, urinary citrate excretion fell from a mean of 252 mg/24 h pre diet initiation to 52 mg/24 h while on the diet. Uric acid excretion remained normal. Patients maintained on the ketogenic diet often have evidence of hypercalciuria, acid urine, and low urinary citrate excretion. In conjunction with low fluid intake, these patients are at high risk for both uric acid and calcium stone formation. Received: 28 May 1999 / Revised: 7 June 2000 / Accepted: 9 June 2000     

Recurrent urolithiasis: a general-practice study of risk factors and clinical consequences

In 93 consecutive outpatients with verified recurrent urolithiasis a clinical and biochemical investigation was performed. In 25 patients with uric acid disorder, the median values for number of stones formed and frequencies of hospital admission and surgical treatment were about twice those in the remainder of the series. No correlation was found between the number of stones or the number of renal colic episodes and the urinary calcium level or Ca/Mg ratio. Stone formation showed numerical increase with increasing 24-hour output of urine, possibly as a result of the observed positive correlation between excretion of uric acid and 24-hour urine volume. Sixty per cent of all the stones were spontaneously excreted. The urolithiasis was associated with increased frequency of urinary tract infection, particularly in men. In about one-third of the patients more than one etiologic factor was present.     

广东南海地区泌尿系结石患者结石成分分析(附986例报告)

【摘要】 目的 应用红外光谱法分析广东南海地区泌尿系结石患者的结石,为临床个性化防治泌尿系结石及复发提供理论依据。方法 通过自然排出、碎石后排出或手术取出获得结石样本986例,并应用红外光谱法对其行结石成分分析。结果 泌尿系结石患者男女比例为1.34∶1,51岁~60岁年龄阶段患者所占比例最高,上尿路结石发病人数明显多于下尿路结石,比例达9.49∶1。定性分析共检测出一水草酸钙、二水草酸钙、碳酸磷灰石、无水尿酸、六水磷酸镁铵和胱氨酸6种化学成分。混合成分结石647例,占总人数的65.6%;含钙结石853例,占86.51%。草酸钙检出率最高,占77.38%,其次是碳酸磷灰石(5.27%)和尿酸(13.29%)成分。结论 采用红外光谱法分析泌尿系结石成分,对于了解结石成因、预防结石形成和复发具有重要的意义。     

Role of the diurnal variation of urinary pH and urinary calcium in urolithiasis: A study in outpatients

BACKGROUND: We previously reported that the urinary excretion of calcium and the diurnal variation of urinary pH were important for stone formation in hospitalized inpatients with hospital standard diet. Because almost all urinary stones are formed in outpatients with ambulatory free diet, it is essential to investigate these factors in outpatients. METHODS: We examined the urinary excretion of calcium, oxalate, uric acid, phosphate and magnesium in 96 male outpatients and 142 male inpatients. We also studied the relationship between the stone composition and the diurnal variation of urinary pH in 32 male outpatients (five uric acid stones (UA), 13 pure calcium oxalate stones (CaOX) and 14 mixed calcium oxalate and calcium phosphate stones (CaOX-CaP)) and 53 male inpatients (nine UA, 15 CaOX and 29 CaOX-CaP). RESULTS: There was a significant difference in the urinary excretion of calcium among outpatients with UA, CaOX and CaOX-CaP (133 +/- 96 vs 219 +/- 97 vs 268 +/- 102 mg per day, P < 0.05). In outpatients with UA, urinary pH was constantly low throughout the entire day. In contrast, outpatients with CaOX and those with CaOX-CaP had diurnal variation of urinary pH that was low in the early morning, followed by elevation in the daytime and was lowered in the night. The pHs in the early morning, afternoon and night were significantly higher in outpatients with CaOX-CaP than in those with CaOX. CONCLUSION: The diurnal variation of urinary pH and the urinary calcium are important for stone formation.     

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.     

Epidemiological characteristics of urolithiasis in Okhotsk coast area in Hokkaido

An epidemiological study of 422 stone-formers who visited our hospital from 1997 to 2001 was conducted. The mean annual prevalence and incidence of both upper and lower urinary tract stones were higher than what was found in a nationwide urolithiasis survey carried out in Japan in 1995. The incidence of upper and lower urinary tract stones was 90.8% and 9.2%, respectively. The frequency of lower urinary tract stones was higher than that found in the previously mentioned nationwide study. The male-to-female ratio of upper and lower urinary tract stones was 1.68:1 and 2.25:1, respectively. The frequency in females was higher in this study than that found in the nationwide survey. The peak age for incidence of upper urinary tract stones is 50s in males and females. In the treatment of upper urinary tract stones, ureteroscopic lithotripsy was carried out more often than shock wave lithotripsy (SWL), because our hospital had no SWL device. Many endoscopic lithotripsy procedures were performed to treat stones located in the lower urinary tract. Of the upper urinary tract stones 83.7% were composed of calcium, the incidence of uric acid stones was high (6.6%), whereas the incidence of infectious stones was low (1.9%). For lower urinary tract stones, the frequency of infectious stones was high (52.6%). In the present study, the epidemiological features were as follows: high annual prevalence and incidence, high frequency of lower urinary tract stones, high frequency in females, many endoscopic treatment procedures and high frequency of uric acid stones in the upper urinary tract.     

Urinary stone composition in North-East Thailand

Stones removed from 120 adults and 22 children were analysed for chemical composition. Calcium oxalate was the main component of both adult (49%) and childhood (44%) stones. Calcium stones formed the major type in adults and were slightly more common in males, whereas urate/uric acid stones were predominant in children and were more common in girls. In adults, the stones were usually found in the upper urinary tract (UUT) and were mainly of calcium type (72%), while all three types were found in almost equal amounts in the lower urinary tract (LUT). Magnesium ammonium phosphate and urate/uric acid were the stones found mainly in the upper and lower urinary tracts respectively of children.     

广东东莞地区416例泌尿系结石成分分析

目的 应用红外光谱法测定东莞地区泌尿系结石化学成分,探讨本地区泌尿系结石患者的尿路结石成分特点,为本地区泌尿系结石的深化治疗、防止结石复发及预防提供科学依据.方法 收集经自行排出、碎石后排出或手术中取出的泌尿系结石标本416例,应用溴化钾压片技术的红外光谱法对其化学成分进行定性分析.结果 416例泌尿系结石患者中男性居多,占66.8%(278/416),女性占33.2%(138/416);上尿路结石占88.2%,下尿路结石(膀胱结石居多)占11.8%;结石成分定性分析共检测出一水草酸钙、二水草酸钙、碳酸磷灰石、无水尿酸、六水磷酸铵镁和尿酸铵6种化学成分.单一成分结石163例(一水草酸钙/无水尿酸/碳酸磷灰石/六水磷酸铵镁:98/56/6/3),占39.2%;混合成分结石253例,占60.8%,其中以草酸钙和碳酸磷灰石的混合结石为主(188/253).所有结石标本中草酸钙检出率最高,占80.5%(335/416),其次为碳酸磷灰石(49.3%)及无水尿酸(17.3%);膀胱结石成分以一水草酸钙或无水尿酸为主.结论 东莞为全国泌尿系结石最高发地区,其结石成分以草酸钙和碳酸磷灰石为主,单一成分结石亦占相当比例.尿路结石成分分析对了解结石成因可提供重要的线索,对临床制定个性化治疗方案、预防结石形成及复发具有重要意义.     

Pattern of urolithiasis in Brooklyn, New York

Crystallographic analysis of 261 upper urinary tract calculi from patients in Brooklyn is presented. Calcium oxalate, uric acid, and struvite stones predominate. We could not confirm the hypothesis that uric acid forms a nidus in calcium oxalate urolithiasis in spite of a percentage of uric acid calculi more than twice the national average.     

Should recurrent calcium oxalate stone formers become vegetarians?

The hypothesis that the incidence of calcium stone disease is related to the consumption of animal protein has been examined. Within the male population, recurrent idiopathic stone formers consumed more animal protein than did normal subjects. Single stone formers had animal protein intakes intermediate between those of normal men and those of recurrent stone formers. A high animal protein intake caused a significant increase in the urinary excretion of calcium, oxalate and uric acid, 3 of the 6 main urinary risk factors for calcium stone formation. The overall relative probability of forming stones, calculated from the combination of the 6 main urinary risk factors, was markedly increased by a high animal protein diet. Conversely, a low animal protein intake, such as taken by vegetarians, was associated with a low excretion of calcium, oxalate and uric acid and a low relative probability of forming stones.