Analysis of urinary calculi composition by infrared spectroscopy: a prospective study of 625 patients in eastern China

Urolithiasis is a common urologic disease whose prevalence is about 1–20% and increasing throughout the world. The recurrence rate after treatment is more than 50%. Urinary stone analysis is important in determining the possible etiology and the pathophysiology of stone formation. A better understanding of the stone composition may help prevent urinary stone formation. From March 2007 to December 2008, physical analysis of urolithiasis in patients who lived in eastern China for more than 5 years and underwent surgery or shock wave lithotripsy in our hospital or passed their stones spontaneously was carried out using the Fourier transform infrared spectroscopy (FT-IR). Clinical and demographic findings were evaluated and compared with the stone components. Stone analysis was performed in 625 patients. The FT-IR evaluation showed that 234 (37.4%) were pure, and the most frequent was calcium oxalate (33.9%), followed by calcium phosphate (2.7%), and uric acid (0.8%). 391 (62.6%) were mixed stone, calcium oxalate (43.2%) was the most commonly major component, followed by calcium phosphate (16.3%), cystine (1.3%), uric acid (1.1%), and struvite (0.6%). Uric acid (p = 0.029) was the major component found more frequently in men, while struvite (p = 0.037) was more frequent in women. Uric acid (p = 0.031) was more common in lower urinary tract stones, and its formers with the mean age of 55 years were older than those with other components (p = 0.039). In eastern China, the most commonly found pure stone was calcium oxalate, while the most frequent mixed stone was calcium oxalate and calcium phosphate mixture. Stone location, gender, and age may influence stone component.     

Metabolic and demographic characteristics of children with urolithiasis in Western Turkey

Pediatric urolithiasis is an endemic disease in Turkey. We evaluated the clinical, radiological and metabolic features of children with urolithiasis in Western Turkey. We retrospectively reviewed the records of 85 children with urolithiasis who were followed-up between 2004 and 2010 in Pediatric Nephrology Department of Celal Bayar University, Manisa. The male/female ratio was 1.23/1. The mean age at diagnosis was 66.1 months (range 3–210 months). Family history of urolithiasis was found in 58 (68.2%) patients. 23 (27%) patients were born from consanguineous marriages. Stones were located in the upper urinary tract in 79 (92.9%) patients. In 66 (77.6%) patients, stones were single-sided and 41 (48.2%) patients had multiple stones. Calcium oxalate stones were the most common one among patients in whom stone analysis was performed (78.5%). Hypocitraturia was the most commonly detected urinary metabolic risk factor. In patients who were under 12 months of age at diagnosis, hypercalciuria was the most commonly seen urinary metabolic risk factor. At the end of follow-up period, 24 patients became free of stone disease and 4 patients had recurrence. In conclusion, metabolic abnormalities are common in pediatric stone patients and are strongly associated with recurrence. Considering that urolithiasis in children is an important risk factor for renal failure, early diagnosis, detailed metabolic evaluation and implementing appropriate treatment and follow-up protocols may prevent recurrence and renal damage.     

Course of calcium stone disease without treatment. What can we expect?

OBJECTIVES: The knowledge of the natural history (i.e. the course of the disease without metaphylaxis is the base for establishing rational guidelines for metaphylaxis in urolithiasis. METHODS: This review is based on a Medlinetrade mark Search (1966-1999) and the proceedings of the Bonn-Vienna and European symposia on urolithiasis. Only 31 references were sufficient for the purpose of this review. RESULTS: In idiopathic calcium stone disease, stone frequency without metaphylaxis is 0.10-0.15 stones per patient per year. The average recurrence rate is 30-40%. Recurrence rate increases with age and observation time. Risk for recurrence is highest during the first 4 years after the first stone episode. More than 50% of all recurrent stone formers have only one recurrence during their lives. 10% of recurrent stone formers have more than 3 recurrences. Risk factors for recurrence are: male sex, multiple and lower calyx stones, early onset, familial history, complications after stone removal. Metabolic evaluation is a poor predictor of the risk for recurrence. CONCLUSIONS: Renunciation of metaphylaxis is justified in first stone formers with idiopathic calcium oxalate and apatite stones. All patients, however, should be advised to increase their fluid intake.     

Diagnosis and management of non-calcium-containing stones in the pediatric population

Compared to adults, urolithiasis is less common in children, with a definite rise in incidence, especially among young adults (Tasian et al. in Clin J Am Soc Nephrol 11:488, 2016). In the last 25 years, the incidence in children has increased by approximately 6–10% annually, for reasons still unknown, with an associated significant increase in related health care-related expenditures (Hyams and Matlaga in Transl Androl Urol 3(3):278–83, 2014). It has been shown that there is twice as high a risk of chronic kidney disease (CKD) or end stage renal disease (ESRD) in stone formers compared to non-stone formers (Tasian et al. 2016). While calcium-containing stones are by far the most common category of stone encountered in both children and adults, non-calcium stones are more common in children than adults and have been shown in several studies to be associated with greater morbidity and lower renal function than calcium stones (Issler et al. in BMC Nephrol 18(1):136, 2017; Gambaro et al. in J Urol 198:268–273, 2017). This could be related to the challenges in the management of non-calcium-containing stones due to associated infection or metabolic derangements, further leading to recurrence and loss of renal function. There is currently a gap in our understanding of how to appropriately and effectively encounter and manage patients with non-calcium-containing stones, as such cases are encountered less frequently. Identification of stone composition and appropriate management is very important to reduce serious complications and recurrence, especially in non-calcium stones. We present a review of diagnosis and management of non-calcium-containing stones in the pediatric population, in hopes of providing more clarity to providers and promoting a consideration of non-calcium stone composition with all children presenting with urolithiasis.     

Effect of potassium citrate therapy on stone recurrence and residual fragments after shockwave lithotripsy in lower caliceal calcium oxalate urolithiasis: a randomized controlled trial

BACKGROUND AND PURPOSE: To evaluate the efficacy of potassium citrate treatment in preventing stone recurrences and residual fragments after shockwave lithotripsy (SWL) for lower pole calcium oxalate urolithiasis. PATIENTS AND METHODS: One hundred ten patients who underwent SWL because of lower caliceal stones and who were stone free or who had residual stone 4 weeks later were enrolled in the study. The average patient age was 41.7 years. All patients had documented simple calcium oxalate lithiasis without urinary tract infection and with normal renal morphology and function. Four weeks after SWL, patients who were stone free (N = 56) and patients who had residual stones (N = 34) were independently randomized into two subgroups that were matched for sex, age, and urinary values of citrate, calcium, and uric acid. One group was given oral potassium citrate 60 mEq per day, and the other group served as controls. RESULTS: In patients who were stone free after SWL and receiving medical treatment, the stone recurrence rate at 12 months was 0 whereas untreated patients showed a 28.5% stone recurrence rate (P < 0.05). Similarly, in the residual fragment group, the medically treated patients had a significantly greater remission rate than the untreated patients (44.5 v 12.5%; P < 0.05). CONCLUSION: Potassium citrate therapy significantly alleviated calcium oxalate stone activity after SWL for lower pole stones in patients who were stone free. An important observation was the beneficial effect of medical treatment on stone activity after SWL among patients with residual calculi.     

Urolithiasis associated with protease inhibitors.

OBJECTIVE: We evaluated the radiographic characteristics as well as the clinical management of urolithiasis induced by systemic therapy with indinavir sulfate, a protease inhibitor utilized in the treatment of HIV infection. PATIENTS AND METHODS: Fifteen consecutive HIV-positive male patients (average age 41.3 years) who presented with urolithiasis while being treated with indinavir sulfate (average time 11.1 months) were studied. RESULTS: All patients presented with flank pain, and eight had gross hematuria. All but one patient had microscopic hematuria. The location of the stones was the kidney in three, the proximal ureter in four, and the distal ureter in nine. One patient had both a renal and a proximal ureteral stone. The stones were radiolucent on CT imaging in five patients and could not be seen in five. In the five cases in which a stone was not definitely identified, a diagnosis of urolithiasis was established on the basis of ureteral obstruction and periureteral/renal streaking noted on CT. Treatment included observation with hydration in eight patients, ureteral stent placement in two patients, ureteroscopy in three patients, and extracorporeal shockwave lithotripsy in two patients. Stones were analyzed in five patients and proved to be 100% indinavir in three and a mixture of indinavir, calcium oxalate monohydrate, and calcium oxalate dihydrate in two. CONCLUSIONS: Urolithiasis is a recognized complication of treatment with indinavir sulfate. Pure indinavir stones cannot be seen on CT unless intravenous contrast medium is utilized. Mixed calcium and indinavir stones can occur and may be radiopaque. The majority of HIV-positive patients with symptomatic urolithiasis can be treated conservatively with hydration. Metabolic evaluation of these patients with identification and correction of factors predisposing to stone formation may minimize future recurrences. Administration of this effective medication thus can continue uninterrupted.     

Relationship between metabolic acidosis and calcium phosphate urinary stone formation in women

The relationship between the degree of metabolic acidosis and calcium phosphate stone formation was studied. Furthermore, the reasons why renal tubular acidosis (RTA) and primary hyperparathyroidism (PHPT) dominantly occur in women, and female stone formers more often produce calcium phosphate stone are discussed. Blood was slightly more acidotic in women than in men in both the urolithiasis and the control groups. Likewise, blood was significantly more acidotic and urinary pH significantly higher in patients with PHPT. Patients with RTA had severe metabolic acidosis, and urinary pH was highest among all groups. Calcium phosphate concentration was significantly higher in women than in men, and was also higher in patients with PHPT than in those with urolithiasis. All patients with RTA had pure calcium phosphate stones. The reasons why females are more acidotic and have more calcium phosphate in stones are suspected to be related to progesterone and urinary tract infection.     

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.     

Renal geology (quantitative renal stone analysis) by ‘Fourier transform infrared spectroscopy’

AIM: To prospectively determine the precise stone composition (quantitative analysis) by using infrared spectroscopy in patients with urinary stone disease presenting to our clinic. To determine an ideal method for stone analysis suitable for use in a clinical setting. METHODS: After routine and a detailed metabolic workup of all patients of urolithiasis, stone samples of 50 patients of urolithiasis satisfying the entry criteria were subjected to the Fourier transform infrared spectroscopic analysis after adequate sample homogenization at a single testing center. RESULTS: Calcium oxalate monohydrate and dihydrate stone mixture was most commonly encountered in 35 (71%) followed by calcium phosphate, carbonate apatite, magnesium ammonium hexahydrate and xanthine stones. CONCLUSIONS: Fourier transform infrared spectroscopy allows an accurate, reliable quantitative method of stone analysis. It also helps in maintaining a computerized large reference library. Knowledge of precise stone composition may allow the institution of appropriate prophylactic therapy despite the absence of any detectable metabolic abnormalities. This may prevent and or delay stone recurrence.     

Characteristics of patients with staghorn calculi in our experience

PURPOSE: To elucidate the factors contributing to staghorn stone formation in patients. MATERIALS AND METHODS: The records of 82 patients (44 men and 38 women) with complete staghorn calculi were reviewed retrospectively for clinical presentation, metabolic disturbances and anatomical abnormalities. RESULTS: There were 79 unilateral and three bilateral cases. The patient performance of the activities of daily life was assessed with the modified Rankin scale (MRS) and it was found that 69 patients were functionally independent (84.1%, MRS 0-1) and 10 patients had a severe disability (12.2%, MRS 4-5). Seven patients had chronic indwelling catheters (8.5%). A positive urine culture was found in 24.4% of patients. Analysis of stone composition revealed magnesium ammonium phosphate and mixed calcium oxalate-phosphate were the most frequently identified types of stone (32.1% and 22.2%, respectively). Urinary pH was low in patients with uric acid stones (mean 5.4). Hyperuricemia, cystinuria and hypercalciuria were found in 14.6%, 2.4% and 37.8%, respectively. Hypercalciuria was found more frequently in calcium-stone cases. Eleven patients (13.4%) showed structural abnormalities of the kidney. CONCLUSIONS: Our data show that the patients with severe disability, urinary tract infection and hypercalciuria could be recognized more frequently in staghorn calculi compared with common urolithiasis. However, in Western countries, the frequency of both urinary tract infection and struvite stones is much higher than in our data. Other Japanese authors have also reported the low frequency of struvite stones in staghorn calculi, suggesting that various factors other than urinary tract infection possibly contribute to the formation of staghorn calculi in Japan.     

Metabolic risk factors and the effect of metaphylaxis in pediatric stone disease with hypocitraturia

To describe the metabolic risk factors and investigate the effect of prophylaxis based on these factors on long-term recurrence of urolithiasis in pediatric patients with hypocitraturia. One-hundred and twenty-nine pediatric patients who underwent percutaneous nephrolithotomy between January 2008 and June 2011 were evaluated for metabolic risk factors. The patients with hypocitraturia were enrolled in this study and the data were analyzed using statistical methods for a mean period of 2 years for metabolic abnormalities, stone type, and the effect of potassium citrate prophylaxis on stone recurrence. A 24-h urine metabolite analysis revealed one or more metabolic risk factors in 115 (89.2 %) of the patients, whereas 14 (10.8 %) of the patients had no metabolic abnormalities. Eighty-two (63.5 %) of 129 patients had hypocitraturia. Of them, 43 (52 %) were male and 39 (48 %) were female, with a mean age of 9.7 ± 4.9 and 6.7 ± 4.4 (1–16) years, respectively(p = 0.102). Thirty-five (42.7 %) had pure hypocitraturia, and 47 (57.3 %) had two or more metabolic abnormalities. The most common dual metabolic abnormality was hypocitraturia and hypomagnesuria. Seventy-one patients (87 %) with hypocitraturia received medical prophylaxis and continued regularly, whereas 11 (13 %) patients did not receive medical prophylaxis despite being advised to do so. After a mean follow-up of 26.5 ± 9.4 months, the rate of recurrence was 1.4 % in the patients with hypocitraturia who continued prophylaxis and occurred in all of the patients who did not receive prophylaxis (p < 0.001). Calcium oxalate stones (95.2 %) were the most commonly found stones in the stone analysis. Detailed clinical and laboratory evaluations should be performed in children with urolithiasis. Appropriate prophylactic treatment as potassium citrate, should be given to prevent reformation of stones in patient with hypocitraturia.     

A case of urolithiasis associated with short bowel syndrome

We report a case of urolithiasis associated with short bowel syndrome. A 56-year-old woman was admitted to our hospital for asymptomatic bilateral renal stones. She had received extensive resection of small intestine due to strangulating obstructive ileus 7 years ago (residual intestine, only 20 cm). Subsequently, she was in a state of short bowel syndrome. Plain film of kidney, uteter, bladder and computed tomography revealed bilateral renal stones (right 4 mm, left 10 mm). The left renal stone was successfully treated by extracorporeal shock wave lithotripsy. Since the right renal stone was small, no treatment was performed. The stone fragments were composed of calcium oxalate and calcium phosphate, and excessive urinary excretion of oxalate (103.8 mg/day) was observed. In this patient, urolithiasis was diagnosed to be due to enteric hyperoxaluria caused by short bowel syndrome. To prevent the recurrence of stone formation, she was treated with oral administration of calcium lactate, sodium/potassium citrate and magnesium oxide. We review the Japanese literatures on urolithiasis with short bowel syndrome.     

Contemporary Minimally Invasive Surgical Management of Urinary Stones in Children

With increasing incidence of pediatric urolithiasis over the past two decades, surgical management poses specific challenges for urologists because of the high risk of stone recurrence in this population. Keeping this in mind, management aims should be complete stone-free status, preservation of renal function, and prevention of stone recurrence. The incidence of metabolic problems is up to 50%, and ∼30% of cases involve anatomic anomalies. Therefore, in addition to stone removal procedures, treatment of pediatric urolithiasis requires a thorough metabolic and urologic evaluation on an individual basis. Obstructive pathologies and established metabolic abnormalities should be managed. Urine volume should be increased by encouraging adequate fluid intake, and medical therapeutic agents to increase urinary citrate levels may be considered. To select the most appropriate surgical treatment, the location, composition, and size of the stone(s), the anatomy of the collecting system, and the presence of obstruction or any infection in the urinary tract should all be considered. Improvements in instrument technology and increasing experience with adult cases mean that all contemporary endourologic procedures are currently being applied in the management of pediatric urolithiasis in a safe and effective manner. Shockwave lithotripsy is still the first choice for the majority of cases involving upper tract calculi; other minimally invasive methods such as ureterorenoscopy and percutaneous nephrolithotomy require more expertise, but can be successfully applied for excellent stone-free rates with minimal morbidity. In patients with complex and large stones as well as anatomic abnormalities, open surgery will continue to be the preferred treatment option for children.     

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.     

Metaphylaxis of nephrolithiasis

The introduction of extracorporeal shockwave lithotripsy (ESWL), with its noninvasive removal of stones and considerable reduction in the morbidity of stone disease, has revolutionized the therapy of urolithiasis. Unfortunately the propensity for stone recurrence is not altered by removal of stones with ESWL and stone recurrence is still about 50%. Progress in medical treatment has shown how different therapies can prevent the stone recurrence, even though it is often difficult to predict which patient will go on to become a recurrent stone former. With the right evaluation, however, the cause of calculi formation can be treated in 97% of the patients. Primary prevention of urolithiasis includes general prophylaxis in a no-risk population that has never been affected by urinary tract stones, is without familial predisposition, metabolic or genetic alterations, or urinary tract abnormalities or infections and who live in a geographical area that is at risk. Secondary prevention or metaphylaxis of stone disease is aimed at the population at risk, that is patients already affected by the stone disease, with familial predisposition, with urinary tract alterations, with metabolic or genetic alterations (gout, bone or bowel diseases) and urinary infection.     

Recurrence of upper urinary tract calculi

Treatment of upper urinary tract stones has changed greatly. The recurrence of calculi after the discharge was studied in the 634 patients with urolithiasis admitted to our department during the 9 years up to the end of 1984. The recurrence rate in the 325 cases followed for more than 3 months after the disappearance of the original stones, was 15.6% after 2 years, 27.6% after 5 year and 51.4% after 8 years. In recurrent stone formers, the rate of recurrence thereafter was greater than that of primary stone formers. The growth of calculi was rapid in the renal stone former concomitant with urinary tract infection together with a past history of renal surgery. In relation to the composition of the stone, uric acid calculi tended to recur more often than calculi composed of other substances. In view of recurrence, pyelolithotomy is preferred to renal parenchymal incision.     

Experimental and clinical studies on calcium lithiasis. II. Prevention of recurrent calcium stones with thiazides and allopurinol

We evaluated 113 patients with recurrent or multiple calcium urolithiasis at our outpatient stone clinic between 1980 and 1983. Diagnostic categories included hypercalciuria (36 patients), hyperoxaluria (35 patients), and hyperuricosuria (31 patients). Thiazides and/or allopurinol were administered to the hypercalciurics and hyperuricosurics, respectively for prevention of stone recurrence. Patients followed up for more than one year were 23 (male 16, female 7) in the thiazide group, and 15 (male 12, female 3) in the allopurinol group. The mean treatment interval was 2.49 years in the former, and 2.35 years in the latter. The remission rate (percentage of patients without formation of any new stones) was 82.6% in the thiazide group, and 73.3% in the allopurinol group. The group stone formation rate was reduced from 0.85 to 0.35/pt-yr in the thiazide group, and from 0.74 to 0.27/pt-yr in the allopurinol group. Efficacy of these two drugs for the prevention of calcium stone recurrence was observed in this selective therapy, but a careful double blind study should be carried out to draw a definite conclusion.     

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     

Paediatric urolithiasis in Greece

A group of 44 patients, aged from 10 months to 14 years, underwent surgery for urinary calculi over a 7-year period (1982-1989). Eleven patients had bilateral or multiple calculi (total number of stones = 55, 20 of which were staghorn). Metabolic disorders (n = 25) and Proteus urinary infection (n = 15) were the 2 factors most often associated with lithiasis. Of the 55 stones, 51 were removed by open surgery. Complete stone clearance was achieved in 29 of 36 kidneys. Follow-up periods in the remaining 7 renal units (with small residual fragments) ranged from 3.5 to 7.5 years (mean 6.2) and revealed stone recurrence in only 2 patients. Evaluation of childhood urolithiasis should include thorough metabolic investigation and sound surgical judgment; effective management requires prolonged post-operative follow-up.     

Pediatric urolithiasis in sub-saharan Africa: a comparative study in two regions of Cameroon

OBJECTIVE: To determine the composition of caculi and the predisposing factors for stone nucleation and growth in children from two regions of Cameroon. METHODS: This was a cross-sectional study involving 21 children, 17 from the northern and 4 from the southern region, over a 6-year period. Data on age, diet, residence, clinical presentation, location of stone, and results of stone analysis were collated following a preestablished proforma. A computerized analysis of the data was carried out. The constituents of stone sections and nidus were assembled so as to determine the principal causes of stone nucleation and growth. RESULTS: Pediatric urolithiasis was more common in the northern Sahelian belt of Cameroon. Males and rural dwellers were more commonly affected. Endemic (bladder) stone disease was found in the majority of the patients. All stones were mixed. The most frequent constituents of the stones were ammonium urate, struvites, and whewellite in descending order of percentage mean volume per stone. The nidus was available for study in only 10 stones, and its composition revealed heterogeneity of causes of nucleation. The commonest cause for stone formation and growth were infection and hyperuricosuria (malnutrition). CONCLUSIONS: Pediatric bladder stone disease is not uncommon in northern Cameroon. Many factors combined to predispose to stone nucleation and growth, but the level of socioeconomic development was preponderant. Stone composition indicated that urolithiasis in children was a heterogeneous disorder, but hyperuricosuria, insufficient diuresis, and infection associated with malnutrition seemed to be the most common causes.