An association between kidney stone composition and urinary metabolic disturbances in children

ObjectiveTo determine kidney stone composition in children and to correlate stone fractions with urinary pH and metabolic urinary risk factors.Patients and methodsWe studied 135 pediatric patients with upper urinary tract lithiasis in whom excreted or extracted stones were available for analyses. Composition of stones was analyzed. A 24-hour urine assessment included volume, pH and daily excretions of calcium, oxalate, uric acid, cystine, creatinine, phosphate, magnesium and citrate.ResultsCalcium oxalate was the major component of 73% stones, followed by struvite (13%) and calcium phosphate (9%). Uric acid was present in almost half of stones, but in rudimentary amounts. The calcium oxalate content in calculi showed a strong relationship with calciuria, and moderate association with oxaluria, magnesuria and acidification of urine. The percent content of struvite presented reverse and lower correlations with regard to the above parameters. Calcium phosphate stone proportion had low associations with urinary risk factors.ConclusionsCalciuria, oxaluria, magnesuria and low urine pH exerted the biggest influence on calcium oxalate content in pediatric renal stones. Relationships of urinary risk factors with calculi calcium phosphate content were of unclear significance. Urinary citrate excretion did not significantly correlate with kidney stone composition in children.     

Uric acid excretion in children with urolithiasis

Urinary uric acid excretion was assessed in 38 children to determine whether hyperuricuria was a risk factor in children with urolithiasis. Uric acid excretion (measured per deciliter glomerular filtration rate), and fractional excretion of uric acid were similar in 27 children with hypercalciuria and calcium oxalate urinary stones, in six children with idiopathic calcium oxalate urolithiasis, and in five with uric acid urolithiasis, of whom four were white boys and one was an Asian girl. One boy with a urate stone had cystinosis. Serum uric acid concentrations exceeded 6.0 mg/dl (360 mumol/L) in two children with hypercalciuria and in two patients with idiopathic calcium oxalate urolithiasis. None of the children with calcium urolithiasis had excessive urinary excretion of uric acid. In children with hypercalciuria, uric acid excretion did not change significantly when dietary sodium was increased from 1.0 to 5.0 gm/1.73 m2. We conclude that excessive urinary uric acid excretion is seldom an additional risk factor in children with calcium urolithiasis and that dietary sodium chloride does not have a strong influence on urinary excretion of uric acid in children with hypercalciuria.     

Urinary supersaturation of calcium oxalate and phosphate in patients with X-linked hypophosphatemic rickets and in healthy schoolchildren.

Nephrocalcinosis (NC) is a complication of the treatment of X-linked hypophosphatemic rickets (XLHR). Some studies have found that treated patients have enteric hyperoxaluria caused by phosphate therapy and have implicated calcium oxalate, whereas others have found only calcium phosphate in renal biopsy tissue.Aim and methods: We aimed to study the urinary supersaturation of calcium oxalate and calcium phosphate and to determine whether these measures are risk factors for NC. We collected 24-hour urine samples from 20 patients (12 girls) with XLHR, mean +/- SD age 8.2 +/- 4.7 years, and from 79 age-matched members of a healthy control group prospectively. RESULTS: The median 24-hour urine excretions of oxalate, phosphate, and citrate (mmol/1.73 m(2) per day) were significantly increased in patients compared with the control group (oxalate 0.38 vs 0.28, P =. 0012; phosphate 63.1 vs 25.8, P <.0001; citrate 4.18 vs 2.7, P =. 0002). However, no significant differences were seen in the calcium oxalate or calcium phosphate between patients and the control group. No significant differences were seen in 24-hour urine calcium or magnesium excretion between patients and the control group; however, 8 patients had hypercalciuria. A significant higher urine volume in patients compared with the normal group (826 mL/m(2) 24-hour vs 597 mL/m(2) 24-hour; P <.005) was found. Twelve patients had NC at the time of investigation, and although the oxalate excretion was significantly higher in these patients, no significant difference was seen in the relative supersaturation of calcium oxalate monohydrate (CaC(2)O(4).H(2)O) compared with the 8 without NC. CONCLUSIONS: Although 24-hour urine oxalate and phosphate excretion are increased in treated patients with XLHR, there is no increase in the supersaturation of either calcium oxalate or phosphate. Determination of the supersaturation of calcium oxalate or calcium phosphate does not predict the development of NC in XLHR.     

Decreased urinary citrate excretion in type 1a glycogen storage disease

OBJECTIVES: To quantify urinary citrate and calcium excretion and systemic acid-base status in patients with type 1a glycogen storage disease (GSD1a) and to investigate their relationship to renal complications. STUDY DESIGN: Fifteen patients (7 male and 8 female; age range, 3--28 years) were studied during annual evaluations of metabolic control. All were treated with intermittent doses of uncooked cornstarch. Hourly blood sampling and a 24-hour urine collection were obtained while subjects followed their usual home dietary regimen. RESULTS: All but the youngest subject had low levels of citrate excretion (mean 2.4 +/- 1.8 mg/kg/d; 129 +/- 21 mg citrate/g creatinine). Normally, urinary citrate excretion increases with age; however, in patients with GSD1a, a strong inverse exponential relationship was found between age and citrate excretion (r = -0.84, P <.0001). Urinary citrate excretion was unrelated to markers of metabolic control. Hypercalciuria occurred in 9 of 15 patients (mean urinary calcium/creatinine ratio, 0.27 +/- 0.15) and was also inversely correlated with age (r = -0.62, P =.001). CONCLUSIONS: Hypocitraturia that worsens with age occurs in metabolically compensated patients with GSD1a. The combination of low citrate excretion and hypercalciuria appears to be important in the pathogenesis of nephrocalcinosis and nephrolithiasis. Citrate supplementation may be beneficial in preventing or ameliorating nephrocalcinosis and the development of urinary calculi in GSD1a.     

Nephrolithiasis in childhood inflammatory bowel disease

Six children with inflammatory bowel disease and nephrolithiasis are reported. Their mean age at the passage of the first stone was 12.5 years and the mean duration of active inflammatory bowel disease was 34.5 months. Four had ulcerative colitis and two had Crohn's disease. In three patients, the onset of stone disease was associated with a flare in the bowel disease. Stone passage in four patients was accompanied by an increase in abdominal pain; three experienced gross hematuria. Stones from four of the patients were composed primarily of calcium phosphate; stones from the remaining patients contained uric acid and/or calcium oxalate. The pathogenesis of nephrolithiasis as it relates to inflammatory bowel disease is considered and an approach to therapy offered.     

Antibiotic treatment-induced tubular dysfunction as a risk factor for renal stone formation in cystic fibrosis

OBJECTIVES: Our purpose was to characterize the decisive pathophysiologic factors that lead to renal stone formation (nephrolithiasis) in patients with cystic fibrosis (CF). METHODS: Patients with CF (n = 96) were investigated with respect to lithogenic and inhibitory factors of urolithiasis and compared with 30 healthy control patients. They were subdivided into 2 groups, 86 without renal stones and 10 with renal stones. RESULTS: All stones were exclusively composed of calcium oxalate. As a major pathogenic factor, a urinary disequilibrium between promoting and inhibitory components of stone formation, characterized mainly by hypercalciuria, hyperoxaluria, and hypocitraturia, was found in the patients with nephrolithiasis. They tended to have lower plasma phosphate concentrations and an increased urinary phosphate excretion. The citrate/calcium ratio proved to be a valuable means to discriminate patients with renal stones from control patients. Patients with stones had ingested more cotrimoxazole and ceftazidim, cumulatively, than patients without stones. There was an inverse correlation between the amounts of antibiotics ingested and the percentage of tubular phosphate reabsorption (r = -0.91, P <.0046). CONCLUSION: Renal stone formation in patients with CF is caused by a disequilibrium between promoting and inhibitory components of stone formation, which is dominated by hypercalciuria, hyperoxaluria, and hypocitraturia. Treatment with cotrimoxazole and ceftazidim, primarily, may lead to renal proximal tubular damage with an ensuing sequence of phosphate loss, increase of parathyroid hormone secretion, increased 1,25-dihydroxyvitamin D3 formation, and absorptive hypercalciuria.     

Concentrations of antimony in infants dying from SIDS and infants dying from other causes

BACKGROUND—A patient with cystic fibrosis (CF) and repeated calcium oxalate renal stones prompted us to investigate other children for risk factors for this recognised complication of CF.
METHODS—Twenty four hour urinary excretion of calcium, oxalate, and glycolate was measured in children with CF and no symptoms of renal tract stones. Normal diet and treatments were continued.
RESULTS—In 26 children (aged 5-15.9 years) oxalate excretion was correlated with age; 14 of 26 children had oxalate excretion above an age appropriate normal range. There was a positive correlation between oxalate excretion and glycolate excretion. Mean calcium excretion was 0.06 mmol/kg/24 h with 21 of 24 children having calcium excretion below the normal range.
CONCLUSIONS—Hyperoxaluria may reflect malabsorption although correlation between excretion of oxalate and glycolate suggests a portion of the excess oxalate is derived from metabolic processes. The hypocalciuria observed here may protect children with CF from renal stones.

     

草酸钙结石儿童与非结石儿童代谢差异的病例对照研究

目的比较草酸钙结石儿童(病例组)与非结石儿童(对照组)的血液及24小时尿液相关代谢指标差异。方法选取2016年8月至2018年10月在湖南省儿童医院泌尿外科住院治疗并经结石成分分析主要成分为草酸钙的患者75例作为病例组,选取在本院住院治疗的75例非结石儿童(与病例组同年龄,同性别)作为对照组。测定血液及24小时尿液生化结果,比较病例组与对照组的血液及24小时尿液相关代谢指标差异。结果两组单位体重尿量、单位体表面积草酸、单位体重总钙差异无统计学意义(P>0.05);病例组单位体表面积枸橼酸[310.5(228.4,445.6)mg/1.73 m 2]及尿枸橼酸浓度[135.9(103.9,178.6)mg/L]均低于对照组[446.9(251.5,600.4)mg/1.73 m 2,153.3(114.7,257.7)mg/L],差异有统计学意义(P<0.05)。病例组24小时尿液中草酸浓度高于对照组,差异有统计学意义(Z=-3.024,P<0.05)。两组血钾、钙、氯、尿素氮、肌酐、尿酸浓度差异无统计学意义(P>0.05)。病例组[(139.3±2.6)mmol/L]血钠高于对照组[(138.2±1.9)mmol/L],差异有统计学意义(t=2.851,P<0.05)。结论24小时尿液中草酸浓度、枸橼酸浓度及血钠浓度可能与儿童草酸钙结石形成有关,但儿童血钠及24小时尿液中相关代谢产物浓度是否可作为儿童草酸钙结石形成的危险因素,仍有待进一步探讨。     

Calcium, sodium and potassium urinary excretion during the first five days of life in very preterm infants

BACKGROUND: Hypercalciuria has been associated with the risk of nephrocalcinosis and renal stones in both adults and children. Renal calcifications are frequently encountered in preterm infants because this particular population presents most of the risk factors of increased urinary calcium excretion. Urinary calcium excretion has been shown to correlate with sodium and potassium excretions in adult patients, but these correlations have not been demonstrated in the early neonatal period yet. OBJECTIVE: To define the relationship between calcium urinary excretion and sodium or potassium excretions in the first 5 days of life in preterm babies. METHODS: A prospective study was conducted in 16 preterm infants born before 32 weeks of gestation (body weight 1,373 +/- 310 g; gestational age 29.1 +/- 1.6 weeks). Fifteen consecutive 8-hour urine collections were performed for each infant from the 8th hour of life. A plasma sample was obtained at the end of each urine collection. Sodium, potassium, calcium and creatinine were measured in urine and blood samples as often as possible. RESULTS: (1) Urine sodium excretion was 6.56 +/- 4.35 mmol/kg per day. (2) Urinary calcium excretion was 5.9 +/- 5.4 mg/kg per day and the urinary calcium/creatinine ratio was 0.48 +/- 0.39 mg/mg. (3) Urinary calcium and sodium excretion were positively correlated (r = 0.65, p = 0.0001), while an inverse correlation was found between calcium and potassium excretion (r = 0.31, p = 0.004). CONCLUSION: The mean values of urinary calcium excretion and calcium/creatinine ratio observed in our population were higher than 4 mg/kg per day and 0.4 mg/mg, respectively, i.e. boundary values previously associated with an increased risk of nephrocalcinosis. We hypothesize that an increase in urinary sodium excretion in this population may facilitate calcium excretion.     

Urolithiasis in childhood

A retrospective review was performed of the records of 85 children with urinary-tract calculi evaluated and treated during a 12-year period. The study evaluated the patients' age, sex, initial complaints, etiology, relevant pathological factors, stone location, mode of treatment, and stone analysis. There were 68 boys and 17 girls, a ratio of 4:1. Patient age ranged from 10 months to 16 years (average 8.2 years). Flank pain was the most common manifestation. Seventy patients had calculi in the upper urinary tract and 31 in the lower urinary tract; 16 had stones in more than one site and 15 had bilateral stones. Hypercalciuria was the most common metabolic disorder. Most patients underwent open surgical procedures for removal of their calculi; 5 stones were successfully removed endoscopically. In 3 cases, the stones passed spontaneously. Calcium oxalate and calcium phosphate stones were present in 32 cases, struvite in 5, cystine in 2, and uric acid in 1 Urolithiasis is still one of the most common pediatric urologic problems in Turkey, but as living standards improve, the incidence of the disease has tended to decline in recent years. Anatomic anomalies and metabolic disorders are of great importance in the etiology of stone disease. Accepted: 12 July 1999     

Nephrolitiasis in a patient with cystic fibrosis

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Defects in the CFTR gene cause abnormal chloride conductance across the apical membrane of epithelial cells, which results in progressive lung disease and also affects other organs. Because life expectancy has increased, other complications of CF have become more apparent. We present a patient with CF and symptomatic nephrolithiasis. Several stones were evident in both kidneys. A 24-hour urine sample showed hyperoxaluria (141 mg/24 h/ 1.73 m(2)) and hypocitraturia and (206 mg/24 h/1.73 m(2), 177 mg citrate/g creatinine). Nephrolithiasis should be included in the differential diagnosis of patients with CF and abdominal pain; urinary excretion of oxalate and citrate should be investigated.     

儿童特发性高钙尿症的临床代谢特征研究

目的　了解上海地区儿童特发性高钙尿症（ＩＨ）流行病学、临床分型、代谢特点及肾功能状况。方法　对上海地区６４０ 例６ ～１３ 岁正常儿童行尿钙／ 肌酐（Ｃａ／Ｃｒ） 比值、２４ 小时尿钙定量、钙负荷试验筛查ＩＨ;对筛查出的１６ 例ＩＨ儿童行血、尿生化及肾小球和肾小管功能检查。结果　尿Ｃａ／Ｃｒ 值呈偏态分布,与性别无关,但与年龄相关;９ 岁前和９ 岁后其第９５ 百分位值分别为０－２６ 和０－１７;ＩＨ 儿童检出率为２－５０ ％ ,以吸收型ＩＨ 为主;ＩＨ 与家族泌尿系结石的发生密切相关;１６ 例ＩＨ 儿童尿Ｎ－ 乙酰－ β－ Ｄ－ 氨基葡萄糖苷酶增高６ 例,尿转铁蛋白增高２例,尿微量白蛋白及ＩｇＧ 增高各１ 例,而尿常规均正常。结论　本地区儿童ＩＨ 并不少见,无症状性ＩＨ 可引起肾小管功能的损害。     

Urolithiasis in children

Twelve stones from 11 children with urolithiasis treated in the pediatric surgical department from 1976–1981 were quantitatively analyzed by X-ray diffraction. According to clinical picture and stone analysis, the cases fell into two groups: (1) children less than 3 years of age with Proteus sp. infection and staghorn phosphate stones, and (2) children of 5 years or more with uninfected calcium oxalate stones of the renal pelvis or ureter. The quantitative analyses showed that urinary stones in children have the same main types of composition as in adults but may be less complex. The 4.5 : 1 sex distribution of male: female patients, the 33% incidence of malformations of the upper urinary tract, and the 9% frequency of recurrence correspond to figures from other reports.     

Changes in stone composition according to age and gender in Tunisian children

ObjectiveStudies evaluating the influence of age and gender on the distribution of the various types of pediatric urinary calculi are scarce. The aim of this study was to highlight the modification of epidemiological characteristics of this pathology according to patients' sex and age.Patients and methodsA total of 205 calculi (from 122 boys and 83 girls) were analyzed by infrared spectroscopy between 1993 and 2007; 54.6% of the patients were under 5 years.ResultsCalcium oxalate was the predominant constituent in 54.7% of stones, followed by calcium phosphate and purines (14.6% each). We found a predominance of calcium oxalate in females (59.1% vs 50.8%), and a male preponderance for struvite stones (12.3% vs 1.2%). There was an increasing prevalence of calcium oxalate stones with age in both genders (42.9% in infants vs 59.3% in older children). Purine stones were predominant in 20% of cases, but prevalence decreased with age (28.6% in infants vs 18.5% in older children).ConclusionThe increase in calcium oxalate stones in school-age children and the decrease in stones containing purines confirm a change in the etiology of urolithiasis according to age.     

Spectrum of pediatric urolithiasis in western India

Of 1,211 patients with urolithiasis treated at this institution over a nine years period, there were 77 (6.4%) pediatric cases. The commonest age group was 6–10 years (55.8%). Male: female ratio was 7.6∶1. Hindus consituted 72.7% of the patients There was no significant seasonal variation. The commonest site was urinary bladder (67.5%). The upper: lower urinary tract stone ratio was, 1∶2.85. Majority belonged to the lower-middle or poor income groups having a cereal based diet with minimal or poor protein intake. The common constituents of stones were calcium (98.7%), oxalate (87%), phosphate (84.4%) and uric acid (76.6%). Of all these, uric acid had the richest concentration (grade of ++ or more) in 93.2%. Only 4 stones (5.2%) were “pure”: calcium oxalate-3 and calcium phosphate-1; whereas 73 (94.8%) were mixed stones. Of these, 9 (11.7%) were “predominent” mixed stones, with only one constituent having rich concentration (grade of ++ or more) and all others being either trace or +. The rest 64 (83.1%) were “heterogenous” mixed stones having rich concentration of more than one constitutent.     

Metabolic stone composition in Egyptian children

ObjectiveThe composition of urinary stones in children depends on socioeconomic conditions, geography and dietary habits. Pediatric urolithiasis remains endemic in developing countries. The aim of this study was to analyze stone composition in an Egyptian patient population.Patients and methodsWe analyzed prospectively urinary stones from 100 consecutive children (73 males, 27 females), aged 14 months to 12 years. The stones were located in the upper urinary tract in 78%, lower urinary tract in 19% and both in 3%. Male patients had more lower urinary tract stones. On presentation 67% had flank pain and 37% had hematuria. Stones were treated by open surgery in 69% of patients, shockwave lithotripsy in 20% and endoscopic extraction in 13%.ResultsThe components of the upper urinary tract calculi were calcium oxalate (47%), ammonium acid urate (26%) and calcium carbonate (21%), whereas the main components of the lower urinary tract calculi were ammonium acid urate (27.2%), struvite (27.2%) and calcium carbonate (22.7%). Urinary tract infection was involved in the development of one third of the stones. Endemic stones were present in 17% of patients, and stones of metabolic origin in 15%. The etiology of stone formation remained unknown in one third of patients.ConclusionThe epidemiological profile of urinary stones in Egyptian children can now be considered intermediate between developing countries where dietary deficiencies are the main causes and developed countries where infectious and metabolic calculi are observed.     

Hypocitraturia in patients with urolithiasis

The urinary citrate/creatinine ratio was evaluated in 25 children with idiopathic calcium urolithiasis and 24 controls. The mean (SD) urinary citrate/creatinine ratio in controls and patients was 0.510 (0.205) and 0.181 (0.076), respectively, a statistically significant difference. In neither group was there a relation between age and urinary citrate excretion.     

Hypocitraturia in patients with urolithiasis.

The urinary citrate/creatinine ratio was evaluated in 25 children with idiopathic calcium urolithiasis and 24 controls. The mean (SD) urinary citrate/creatinine ratio in controls and patients was 0.510 (0.205) and 0.181 (0.076), respectively, a statistically significant difference. In neither group was there a relation between age and urinary citrate excretion.     

A correlation study between macro- and micro-analysis of pediatric urinary calculi

ObjectiveThe aim was investigate the relationship between macro- and micro-compositions of pediatric urinary stones by using two combined analytical techniques: Fourier transform infrared spectroscopy (FT-IR) and inductively coupled plasma-optical emission spectrometry (ICP-OES).Materials and methodsA total of 74 consecutive urinary calculi were collected from children. Each stone was divided into two equal portions. One part was analyzed by FT-IR to determine mineralogical composition. The second part underwent analysis by ICP-OES to determine the heavy metals and trace elements contents. The association between mineralogical components and elemental contents was evaluated.ResultsThe percentages of mineralogical components of the stones were 78.3% calcium oxalate monohydrate, 63.5% calcium oxalate dihydrate, 24.3% ammonium urate, 13.5% uric acid, 10.9% dahllite, 12.1% brushite, 8.1% ammonium calcium phosphate, 8.1% struvite, 4.5% cysteine, and 2.7% were xanthine. There were seven elements with significant different high concentrations; magnesium, sulfur, strontium, lead, chromium, calcium, and phosphorous. High calcium-containing stones had significant higher contents of magnesium, lead, strontium, and zinc (p < 0.05) than low calcium-containing stones. Phosphate stones had significant contents of magnesium, strontium, zinc and chromium when compared to other stones (p < 0.05).ConclusionsPediatric urinary stones have variable biochemical structures. The stones contained many significant heavy metals and trace elements in different concentrations, and phosphate stones enclosed most of the heavy and trace elements.     

Urinary uric acid : creatinine ratios in healthy Turkish children

Background:  Determining uric acid : creatinine ratios in random urine samples may be useful to assess the excretion of uric acid in children. Because it was shown that urinary uric acid excretion varies with age and geographic area, it is important to have accurate reference values of uric acid excretion. The aim of the present study was therefore to obtain regional reference values for urinary uric acid : creatinine ratios in healthy Turkish children.
Methods:  A total of 1306 children aged 1 month–15 years were analyzed for uric acid and creatinine, and urinary uric acid : creatinine ratios were determined from each sample. The second non-fasting morning urine samples were taken from all the children. Urine samples were analyzed for uric acid using the uricase method, and for creatinine with the Jaffe reaction.
Results:  The mean ± SD and 5th–95th percentiles of urinary uric acid : creatinine ratios (mg/mg) were 1.09 ± 0.48 and 0.27–1.87 at 1–6 months, 0.86 ± 0.41 and 0.19–1.64 at 7–12 months, 0.76 ± 0.32 and 0.32–1.43 at 1–3 years, 0.63 ± 0.29 and 0.20–1.23 at 4–6 years, 0.44 ± 0.24 and 0.14–0.93 at 7–11 years, and 0.30 ± 0.14 and 0.12–0.62 at 12–15 years. Uric acid : creatinine ratios were not significantly different between boys and the girls except at 12–15 years. Girls aged 12–15 years had higher urinary uric acid : creatinine ratio when compared with boys ( P  < 0.05). There was no correlation between urinary uric acid : creatinine ratio and protein intake.
Conclusions:  Urinary uric acid : creatinine ratio changes with age. When assessing urinary uric acid : creatinine ratio, the clinician should consider the age of the child.