Risk factors for developing hyperoxaluria in children with Crohn's disease.

BACKGROUND: For the purpose of a better understanding of enteric hyperoxaluria in Crohn's disease (CD) in children and adolescents, we investigated the occurrence and risk factors for development of hyperoxaluria in those patients. METHODS: Forty-five children with CD and another 45 controls were involved in this cross-sectional study. Urine samples were collected for measurement of spot urine calcium/creatinine (Ur Ca/Cr), oxalate/creatinine (Ur Ox/Cr), and citrate/creatinine (Ur Citr/Cr) ratios. Fecal samples were also collected to detect the oxalyl-CoA decarboxylase of Oxalobacter formigenes by PCR. Patients were classified into 2 groups: group A (with hyperoxaluria) and group B (with normal urine oxalate excretion). The disease extent was assessed, and the activity index was calculated. RESULTS: According to the activity index, 30 patients (66.7%) had mild disease and 13 patients (28.9%) had moderate disease. There was no significant difference in Ur Ox/Cr ratio regarding the disease activity index. O. formigenes was not detected in 91% of patients in group A while it was detected in all patients in group B (p < 0.001). By using logistic regression analysis, the overall model was statistically significant when compared to the null model, (χ2 (7) = 52.19, p < 0.001), steatorrhea (p = 0.004), frequent stools (p = 0.009), and O. formigenes (p < 0.001). CONCLUSION: Lack of intestinal colonization with O. formigenes, steatorrhea, and frequent stools are the main risk factors for development of enteric hyperoxaluria in CD patients. Identifying risk factors facilitates proper disease management in future studies. A higher resolution version of the Graphical abstract is available as Supplementary information.

Posttransplant recurrence of calcium oxalate crystals in patients with primary hyperoxaluria: Incidence, risk factors, and effect on renal allograft function.

Primary hyperoxaluria (PH) is a metabolic defect that results in oxalate overproduction by the liver and leads to kidney failure due to oxalate nephropathy. As oxalate tissue stores are mobilized after transplantation, the transplanted kidney is at risk of recurrent disease. We evaluated surveillance kidney transplant biopsies for recurrent calcium oxalate (CaOx) deposits in 37 kidney transplants (29 simultaneous kidney and liver [K/L] transplants and eight kidney alone [K]) in 36 PH patients and 62 comparison transplants. Median follow-up posttransplant was 9.2 years (IQR: [5.3, 15.1]). The recurrence of CaOx crystals in surveillance biopsies in PH at any time posttransplant was 46% overall (41% in K/L, 62% in K). Higher CaOx crystal index (which accounted for biopsy sample size) was associated with higher plasma and urine oxalate following transplant (p < .01 and p < .02, respectively). There was a trend toward higher graft failure among PH patients with CaOx crystals on surveillance biopsies compared with those without (HR 4.43 [0.88, 22.35], p = .07). CaOx crystal deposition is frequent in kidney transplants in PH patients. The avoidance of high plasma oxalate and reduction of CaOx crystallization may decrease the risk of recurrent oxalate nephropathy following kidney transplantation in patients with PH. This study was approved by the IRB at Mayo Clinic.

What Factors Drive Staghorn vs Nonstaghorn Pattern Growth in Patients with Metabolic Stones?

Purpose: There has been an increase in the number of staghorn calculi that form in the absence of infection (metabolic staghorns). It is unknown why some large metabolic calculi form as solitary or multiple separate, nonbranching caliceal stones, whereas others develop as staghorn stones forming a cast of the collecting system. We sought to compare these two groups of metabolic stone formers (SFs) in an attempt to shed light on these disparate stone-forming phenomena. Materials and Methods: From January 2017 to September 2018, 190 patients underwent percutaneous nephrolithotomy for stones >2 cm. We identified 86 (45%) patients with a metabolic stone, defined as ≥80% calcium oxalate monohydrate or dihydrate and/or calcium phosphate. Exclusion criteria included stones composed of cystine, >20% uric acid, or any infectious element (struvite or carbonate apatite). Metabolic staghorn and nonstaghorn SFs were compared with respect to medical comorbidity, 24-hour urine parameters, stone and urine microbiology, stone compositions, and intraoperative findings. Statistical differences were assessed using chi-square analysis, Fisher's exact test, and Student's t-test. Results: In total, 25 (29%) staghorn and 61 (71%) nonstaghorn SFs were included for analysis. The groups were statistically similar in age, sex, body mass index, and medical comorbidity. Staghorn SFs had larger stone burdens (p < 0.0001), but did not require more punctures (p = 0.783). Staghorn SFs were more likely to have hyperoxaluria (p = 0.041) and higher mean 24-urine oxalate levels (p = 0.040). There were no other significant differences in 24-hour urine profiles, rates of metabolic abnormalities, stone compositions, stone or urine cultures, presence of collecting system obstruction, or pelvicaliceal anatomy. Conclusions: Although potentially driven by urinary oxalate, whether a metabolic stone will form into a staghorn configuration or not does not appear significantly influenced by standard determinants of stone development, including metabolic profile, cultures, hydronephrosis, and pelvicaliceal anatomy, among others. Further work is needed to elucidate the physicochemical factors that govern the pathogenesis of this increasingly prevalent entity.

Urine kidney injury markers do not increase following gastric bypass: a multi-center cross-sectional study.

INTRODUCTION: To determine if markers of kidney injury correlate with urinary oxalate excretion. If so, such biomarkers might be early predictors of oxalate nephropathy. Gastric bypass surgery for obesity is known to be associated with postoperative hyperoxaluria, which can lead to urolithiasis and kidney damage. MATERIALS AND METHODS: Patients were recruited from four large academic centers > 6 months following completion of gastric bypass surgery. Patients provided a spot urine sample for analysis of three markers of kidney injury: 8-iso-Prostaglandin F2 α, N-acetyl- ß -D-Glucosaminidase, and Neutrophil gelatinase-associated lipocalin. Patients also provided 24 hour urine samples for stone risk analysis. RESULTS: A total of 46 study patients provided samples, the average age was 48.4 +/- 11.3. There were 40 women and 6 men. There was no difference in the level of any of the three inflammatory markers between the study group and the reference range generated from healthy non-hyperoxaluric subjects. Neither oxalate excretion nor supersaturation of calcium oxalate correlated with any of the injury markers. There was no difference noted between those with hyperoxaluria (n = 17) and those with normoxaluria (n = 29) with respect to any of the injury markers. CONCLUSIONS: Though hyperoxaluria was common after bypass surgery, markers of kidney injury were not elevated after surgery. No correlation was found between urine oxalate excretion and any of the injury markers.

Steatorrhea and Hyperoxaluria in Severely Obese Patients Before and After Roux-en-Y Gastric Bypass.

BACKGROUND AND AIMS: Hyperoxaluria after Roux-en-Y gastric bypass (RYGB) is generally attributed to fat malabsorption. If hyperoxaluria is indeed caused by fat malabsorption, magnitudes of hyperoxaluria and steatorrhea should correlate. Severely obese patients, prior to bypass, ingest excess dietary fat that can produce hyperphagic steatorrhea. The primary objective of the study was to determine whether urine oxalate excretion correlates with elements of fat balance in severely obese patients before and after RYGB. METHODS: Fat balance and urine oxalate excretion were measured simultaneously in 26 severely obese patients before and 1 year after RYGB, while patients consumed their usual diet. At these time points, stool and urine samples were collected. Steatorrhea and hyperoxaluria were defined as fecal fat >7 g/day and urine oxalate >40 mg/day. Differences were evaluated using paired 2-tailed t tests. RESULTS: Prior to RYGB, 12 of 26 patients had mild to moderate steatorrhea. Average urine oxalate excretion was 61 mg/day; there was no correlation between fecal fat and urine oxalate excretion. After RYGB, 24 of 26 patients had steatorrhea and urine oxalate excretion averaged 69 mg/day, with a positive correlation between fecal fat and urine oxalate excretions (r = 0.71, P < .001). For each 10 g/day increase in fecal fat output, fecal water excretion increased only 46 mL/day. CONCLUSIONS: Steatorrhea and hyperoxaluria were common in obese patients before bypass, but hyperoxaluria was not caused by excess unabsorbed fatty acids. Hyperphagia, obesity, or metabolic syndrome could have produced this previously unrecognized hyperoxaluric state by stimulating absorption or endogenous synthesis of oxalate. Hyperoxaluria after RYGB correlated with steatorrhea and was presumably caused by excess fatty acids in the intestinal lumen. Because post-bypass steatorrhea caused little increase in fecal water excretion, most patients with steatorrhea did not consider themselves to have diarrhea. Before and after RYGB, high oxalate intake contributed to the severity of hyperoxaluria.

Metabolic disturbances in Chinese children with urolithiasis: a single center report.

Urinary stones and urine composition are the first steps in the process of recurrence prevention, but data concerning the association between the two compositions are scarce in Chinese children with urolithiasis. We retrospectively analyzed the records of children (age range 0-18 years) with urolithiasis in our center between March 2004 and December 2013. Stone analysis was carried out in 382 children and 24-hour urine analysis in 80 children. Analysis of both stone and 24-hour urine composition was completed in 56 children. Stone samples were analyzed by Fourier transform-infrared spectrometry. The major stone constituents were calcium oxalate (78.8 %). Of 80 children with 24 h urine analysis, only 2.5 % were without urinary metabolic abnormalities. Hypocitraturia was recorded in 97.5 %, high sodium excretion in 50.0 %, cystinuria in 48.7 %, hypercalciuria in 18.8 %, small urine volumes in 12.5 %, hyperoxaluria in 5.0 % and hyperuricosuria in 1.3 %. Interestingly, higher urine volumes were recorded in girls than in boys (73.2 ± 58.5 vs 51.3 ± 45.3 mL/kg, p = 0.036). Urine sodium (p = 0.002) and oxalate (p = 0.004) were significantly higher in children >9 year old. Moreover, compared with calcium oxalate stone formers, the urine volume (p = 0.040), citrate (p = 0.007) and cystine (p = 0.004) were higher in patients with cystine stones. Hypocitraturia was the common abnormality among Chinese children with urolithiasis. The surprisingly high incidence of cystinuria is of note.

Metabolic features and renal outcomes of urolithiasis in children.

AIM: The incidence of pediatric urolithiasis has increased over the last century because of dietary changes, metabolic abnormalities, climate change, and genitourinary abnormalities. Data on pediatric urolithiasis in non-endemic countries are limited. The aim of this study was to evaluate the clinical findings and metabolic etiology of urolithiasis in Korean children. MATERIAL AND METHODS: The medical records of 73 Korean children who were newly diagnosed with urolithiasis from January 2010 to December 2013 were retrospectively analyzed. Evaluation of metabolic risk factors, including hypercalciuria, hyperuricosuria, hypomagnesuria, hyperoxaluria, and hypocitraturia, required analysis of 24-h urine specimens or, alternatively, for infants and toddlers, the solute-creatinine ratio in spot urine. RESULTS: The male-to-female ratio of the included patients was 1.3:1. The median age at diagnosis was 10.1 years, and the patients were divided into two age groups with pre-school-age children (n = 27, 37.0%) and school-age children (n = 46, 63.0%). While flank pain was more common in school-age children, incidentally detected or urinary tract infection (UTI)-associated urolithiasis was more common in pre-school-age children. Eight patients (11.0%) had renal function deterioration associated with urolithiasis, and three patients (4.1%) progressed to chronic kidney disease. Metabolic abnormalities according to urine chemistry were found in 30 patients (41.1%), including hypercalciuria in 21.9%, hyperuricosuria in 11.0%, hypomagnesuria in 4.1%, hyperoxaluria in 1.4%, hypocitraturia in 1.4%, and cystinuria in 1.4%. CONCLUSION: We suggest that school-age children with renal colic and pre-school-age children with UTI should be evaluated for urolithiasis. Additionally, the evaluation for metabolic risk factors is important in order to prevent recurrence and renal insufficiency.

Metabolic disorders in Turkish children with urolithiasis.

OBJECTIVE: To review metabolic disorders in Turkish children with urinary tract stone disease. MATERIALS AND METHODS: The medical records of 308 pediatric patients with the diagnosis of urolithiasis between 1996 and 2008, whose disease progression was followed in a single tertiary-care center, were reviewed retrospectively. Two hundred forty-eight patients whose metabolic analyses were performed were included in the study. RESULTS: Of the 248 patients participating in the study, 142 (57%) were men and 106 (43%) were women. The median age of the patients was 48 months (minimum-maximum, 2-180 months). Seventy-six percent of the patients had metabolic disorders. Of all patients, 44% had 1, 23% had 2, and 7% had 3 metabolic disorders. Hypercalciuria, hypocitraturia, hyperoxaluria, hyperuricosuria, and cystinuria were detected in 41%, 39%, 22%, 9%, and 4% of the patients, respectively. The rate of multiple stone formation, infection, and recurrence was significantly higher in the 0-2 years age group (P = .030, P = .001, P = .019, respectively). The median age of patients was greater (P = .001) in patients with hyperoxaluria in comparison with other metabolic disorders. Compared with other metabolic disorders, multiple stones and recurrence were more frequent in patients with cystinuria (P = .022 and P = .008, respectively). The size of the stones was greater in patients with hyperuricosuria in comparison with other metabolic disorders (P = .009). CONCLUSION: The majority of children with urinary tract stone disease exhibited ≥1 metabolic risk factors. Metabolic risk factors should be evaluated in all children with urinary stone disease to provide appropriate treatment.

Kidney stone risk following modern bariatric surgery.

Over the past 10 years, a variety of reports have linked bariatric surgery to metabolic changes that alter kidney stone risk. Most of these studies were retrospective, lacked appropriate controls, or involved bariatric patients with a variety of inclusion criteria. Despite these limitations, recent clinical and experimental research has contributed to our understanding of the pathophysiology of stone disease in this high-risk population. This review summarizes the urinary chemistry profiles that may be responsible for the increased kidney stone incidence seen in contemporary epidemiological bariatric studies, outlines the mechanisms of hyperoxaluria and potential therapies through a newly described experimental bariatric animal model, and provides a focused appraisal of recommendations for reducing stone risk in bariatric stone formers.

Comparison of renal function and metabolic abnormalities of cystine stone patients and calcium oxalate stone patients in China.

PURPOSE: To compare renal function and metabolic abnormalities of cystine stone patients and calcium oxalate stone patients in China. METHODS: Between 2008 and 2011, thirty cystine stone patients were involved in our study, and an equal number of age- and gender pair-matched patients with calcium oxalate stones. Non-stone forming individuals were elected as controls. The evaluation included blood chemistry studies and 24-h urine collection in both groups of patients. RESULTS: The cystine stone patients had higher mean values of serum blood urea nitrogen, urate and creatinine levels than patients in other two groups. With respect to urine risk factors, cystine stone patients had higher urinary citrate and lower urinary oxalate and creatinine than calcium oxalate stone patients. When compared to non-stone forming individuals, cystine stone patients had higher urinary urate excretion and lower urinary creatinine excretion. Metabolic abnormalities could be demonstrated in 80 % of the cystine stone patients and in 100 % of the calcium oxalate stone patients. We also compared urine risk factors among cystine stone patients with different urine cystine excretion (<1 mmol/24 h, 1-2 mmol/24 h and >2 mmol/24 h). No significant difference was found in urine risk factors among three groups. CONCLUSIONS: This study suggested that cystine stone patients were at greater risk for the loss of renal function than calcium oxalate stone patients, but the risk of the formation of calcium oxalate stones was lower. Our results also indicated that urinary cystine had little or no impact on the excretion of urine chemistries in cystine stone patients.

Prevalence and metabolic abnormalities of vitamin D-inadequate patients presenting with urolithiasis to a tertiary stone clinic.

OBJECTIVE: To assess the prevalence and metabolic abnormalities of patients with inadequate vitamin D (VD) presenting with urolithiasis to a tertiary stone clinic in North America. MATERIAL AND METHODS: A retrospective review of consecutive patients presenting from August 2009 to January 2010 was performed. Demographic and clinical data were collected together with metabolic stone workup, including 2 24-hour urine collections and serum 25-hydroxy VD [25(OH)D]. VD inadequacy (VDI) included VD deficiency and VD insufficiency defined as 25-(OH) VD levels <20 ng/mL and 21-29 ng/mL, respectively. RESULTS: Of 101 patients, 81 (80.2%) were found to have VDI: 34 (33.7%) were deficient and 47 (46.5%) had insufficient VD. Mean age was 50.4 ± 15.8 years and the mean body mass index was 28.7 ± 5.8 kg/m(2). Forty-two percent were smokers, 51% were recurrent stone formers, and 54% had positive family history of urolithiasis. Hyperparathyroidism was detected in 25.9% of patients, of which 91% of them were secondary to VDI. Hypocalcemia and hyperuricemia were found in 36% and 11% of patients, respectively. Of 81 VDI patients, 69 (85.2%) had complete 24-hour urine collections, of which 92.7% had at least one abnormality. However, only 40% of patients with normal VD had metabolic abnormalities (P <.0001). The most prevalent pattern of urinary abnormalities in VDI patients were suboptimal volume (45%), hypocitaturia (24%), hypocalciuria (33%), hypercalciuria (20%), hyperuricosuria (16%), cystinuria (5%), and hyperoxaluria (7.2%). CONCLUSION: In this preliminary study, patients presenting with urolithiasis were found to have a high prevalence of inadequate VD associated with abnormalities on metabolic stone work-up.

Renal impairment in children with cystic fibrosis.

BACKGROUND: Due to the improvement in life expectancy in cystic fibrosis (CF), co-morbidities such as renal function impairment may be more frequent. AIM: To determine the prevalence of renal disease in children with CF and to identify associated risk factors. METHODS: A single-center retrospective study analyzing the genetic, clinical and therapeutic characteristics of 112 children. The estimated glomerular filtration rate (GFR), microalbuminuria and lithiasic risk factors were assessed. RESULTS: The median calculated GFR (Schwartz) was 123, 161 and 155ml/min/1.73m(2) in children aged 1, 6 and 15years, respectively. The cumulative dose of aminoglycosides was not correlated to GFR. Microalbuminuria was present in 22/38 patients. Hyperoxaluria was observed in 58/83 patients and was associated with a severe genotype, pancreas insufficiency and liver disease. Hypercalciuria, hyperuricuria and hypocitraturia were identified in 16/87, 15/83 and 57/76 patients, respectively. CONCLUSION: Renal impairment in CF has various presentations. There appears to be low levels of renal impairment in children with CF. However, the risk of oxalocalcic urolithiasis is enhanced, and GFR may be underestimated by the Schwartz formula. Further studies using measured GFR techniques are thus warranted.

Hypocitraturia and hyperoxaluria after Roux-en-Y gastric bypass surgery.

PURPOSE: Roux-en-Y gastric bypass surgery is associated with an increased risk of nephrolithiasis but obesity itself is a known risk factor for kidney stones. To assess the mechanism(s) predisposing to nephrolithiasis after Roux-en-Y gastric bypass we compared urinary tract stone risk profiles in patients who underwent the procedure and normal obese individuals. MATERIALS AND METHODS: In this cross-sectional study urine and serum biochemistry was evaluated in 19 nonstone forming patients after Roux-en-Y gastric bypass and in 19 gender, age and body mass index matched obese controls without a history of nephrolithiasis. RESULTS: Compared with obese controls surgical patients had significantly higher mean +/- SD urine oxalate (45 +/- 21 vs 30 +/- 11 mg daily, p = 0.01) and lower urine citrate (358 +/- 357 vs 767 +/- 307 mg daily, p <0.01). The prevalence of hyperoxaluria (47% vs 10.5%, p = 0.02) and hypocitraturia (63% vs 5%, p <0.01) was significantly higher in surgical patients, who also had significantly lower urine calcium than obese controls (115 +/- 93 vs 196 +/- 123 mg daily, p = 0.03). The calcium oxalate urine relative supersaturation ratio was not significantly different between the 2 groups. CONCLUSIONS: Almost half of patients with Roux-en-Y gastric bypass without a history of nephrolithiasis showed hyperoxaluria or hypocitraturia. This prevalence was significantly higher than in body mass index matched controls. These risk factors were negated by lower urine calcium excretion in patients with Roux-en-Y gastric bypass.

Metabolic factors associated with urinary calculi in children.

INTRODUCTION: We aimed to identify metabolic and anatomical abnormalities present in children with urinary calculi. MATERIALS AND METHODS: Metabolic evaluation was done in 142 pediatric calculus formers. Evaluation included serum biochemistry; measurement of daily excretion of urinary calcium, uric acid, oxalate, citrate, and magnesium (in older children); and measurement of calcium, uric acid, oxalate, and creatinine in random urine samples in nontoilet-trained patients. Urinary tests for cystinuria were also performed. All of the patients underwent renal ultrasonography. RESULTS: Sixty-one patients (42.7%) had metabolic abnormalities. Anatomical abnormalities were found in 12 patients (8.4%). Three children (2.1%) had infectious calculi, and 3(2.1%) had a combination of metabolic and anatomic abnormalities. In 66 children (46.2 %) we did not find any reasons for calculus formation (idiopathic). Urinalysis revealed hypercalciuria in 25 (17.6%), hyperuricosuria in 23 (16.1%), hyperoxaluria in 17 (11.9%), cystinuria in 9 (6.3%), hypocitraturia in 3 (2.1%), and low urinary magnesium level in 1 (0.7%) patients. Sixteen patients (11.2%) had mixed metabolic abnormalities. CONCLUSIONS: Metabolic abnormalities are common in pediatric patients with urinary calculi. In our study, calcium and uric acid abnormalities were the most common, and vesicoureteral reflux seemed to be the most common urological abnormality which led to urinary stasis and calculus formation.

Urolithiasis in the first year of life.

Data on urolithiasis (UL) in infancy are limited. The objective of this study was to increase awareness of infant UL and to investigate the influence of possible risk factors in this very specific age group. Nonfasting, second-voiding urine samples were obtained to test for urinary excretions of calcium, oxalate, citrate, magnesium, uric acid, and creatinine. Blood analysis included calcium, phosphate, magnesium, uric acid, creatinine, sodium, potassium, chloride, and alkaline phosphatase. Patients received follow-up testing every 1-2 months; serial ultrasonography was used to track UL status. Fifty infants with a median age of 5 months were enrolled in the study. Hypercalciuria was detected in 9/47, hyperoxaluria in 5/39, hypocitraturia in 4/31, and cystinuria in 2/50 infants. We identified at least one metabolic abnormality in 46% of our patients; no metabolic abnormality was identified in 27 infants. Within a mean follow-up period of 14 months, 17 infants became stone free, stones increased in number in ten patients and decreased in number in 16, and recurrence was detected in seven. This study showed that UL could be detected in very early life, even in the newborn period, and could be the source of late childhood/adulthood UL. Infants with nonspecific symptoms such as restlessness may have UL and should undergo ultrasonographic examination. Metabolic evaluation of UL in this specific age group carries some diagnostic challenges, e.g. unsatisfactory data regarding normal ranges of urinary mineral excretion, and collection of 24-h urine samples.

Pediatric stone disease.

Urinary stone disease is less common in children than adults. Although many aspects of pediatric stone disease are similar to that of adults, there are unique concerns regarding the presentation, diagnosis, and management of stone disease in children. We present a review of the increasing prevalence of pediatric stone disease, the diagnostic concerns specific to children, recent results from pediatric series regarding the expectant management and surgical treatment of stones, metabolic evaluation, and current research on the genetics of nephrolithiasis.

Prevalence of hyperoxaluria after bariatric surgery.

PURPOSE: Recent investigations have shown increased oxalate excretion in patients in whom kidney stones formed after contemporary bariatric surgery. We determined whether there is an increased prevalence of hyperoxaluria after such procedures performed in nonstone formers. MATERIALS AND METHODS: A total of 58 nonstone forming adults who underwent laparoscopic Roux-en-Y (52) or a biliopancreatic diversion-duodenal switch procedure (6) collected 24-hour urine specimens 6 months or greater after bariatric surgery. Standard stone risk parameters were assessed. Comparisons were made with a group of healthy nonstone forming adults and stone formers in a commercial database. RESULTS: The bariatric group had a significantly higher mean urinary oxalate excretion compared to that in controls and stone formers (67.2 vs 34.1 and 37.0 mg per day, respectively, p <0.001). Mean oxalate excretion of patients who underwent a biliopancreatic diversion-duodenal switch procedure was higher than in the Roux-en-Y group (90 vs 62 mg per day, p <0.05). There was a significant correlation between urine oxalate excretion on the 2 collection days but some patients showed significant variability. Of the patients 74% showed hyperoxaluria in at least 1, 24-hour urine collection and 26% demonstrated profound hyperoxaluria, defined as oxalate excretion more than 100 mg per day, in at least 1 collection. This occurred in 3 of the 6 patients in the biliopancreatic diversion-duodenal switch group and in 12 of the 52 in the Roux-en-Y cohort. Hyperoxaluria was not uniformly expressed. CONCLUSIONS: There is a high prevalence of hyperoxaluria in patients without a history of kidney stones who undergo bariatric surgery. A significant proportion of these patients have profound hyperoxaluria, which is not uniformly expressed.

Estudio metabólico en pacientes con urolitiasis de alto riesgo de recurrencia / Metabolic study in patients with urinary lithiasis at high risk of recurrence

Introducción: La urolitiasis es considerada actualmente una enfermedad metabólica con tendencia ala recurrencia. El objetivo de este trabajo es evaluar la prevalencia de alteraciones metabólicas en pacientes de alto riesgo y su impacto según sexo y edad. Materiales y métodos: Es un estudio descriptivo de 36 pacientes (25 hombres y 11 mujeres), portadores de patología litiásica con alto riesgo de recurrencia. El estudio metabólico consistió en: calcemia, uricemia, fosfemia, PTH sérica, calciuria/24 hrs, uricosuria/24 hrs, fosfaturia/24 hrs, oxalaturia/24 hrs,citraturia/24 hrs y creatininuria/24 hrs. Los valores obtenidos fueron ajustados de acuerdo a la creatininuria y peso. Para el análisis estadístico se utilizó t-student (STATA 7.0). Se consideró significativo p<0,05.Resultados: En el 69 por ciento (25/36) se observó alguna alteración metabólica; el 36 por ciento (13/36) presentó 2 omás alteraciones metabólicas. Las alteraciones más frecuentes fueron la hipercalciuria (30,6 por ciento; 11/36), la hipocitraturia (30,6 por ciento; 11/36), la hiperuricemia (19,4 por ciento; 7/36) y la hiperoxalaturia (13, por ciento; 5/36).No se observó diferencias significativas de edad o sexo entre los grupos con y sin alteración metabólica. Conclusiones: La mayoría de los pacientes con patología litiásica recurrente o de alto riesgo presentan una o más alteraciones metabólicas, predominando la hipercalciuria y la hipocitraturia. En este estudio no hubo diferencias entre ambos sexos en la mayoría de las alteraciones metabólicas, ni tampoco en su distribución etaria. Estos resultados demuestran la necesidad de realizar estudios metabólicos en pacientes de alto riesgo, dado que existen herramientas terapéuticas que permiten un manejo médico de las alteraciones metabólicas y de esta forma reducir la recurrencia de litiasis.

Introduction: Urolithiasis is a metabolic disorder with a tendency to relapse. The aim of this study was to assess the prevalence of metabolic abnormalities in patients at high risk and the impact of sex and age. Materials and methods: Descriptive study of 36 patients (25 men and 11 women),with lithiasic pathology at high risk of recurrence. The metabolic study included the measurement of calcemia, uricemia, fosfemia, parathormone, calciuria/24hrs, uricosuria/24hrs, fosfaturia/24hrs, oxalaturia/24hrs, citraturia/ 24hrs and creatinine/24hrs. The values obtained were corrected according to weight and creatinine. The test used for statistical analysis was t-student (STATA 7.0). It was considered significant p <0.05.Results: In 69 percent (25/36) of the cases a metabolic abnormality was observed and in 36 percent (13/36) there was 2 or more alterations present. The metabolic disorders most frequently observed were hypercalciuria (30.6 percent; 11/36), hypocitraturia (30.6 percent; 11/36), hyperuricemia (19.4 percent; 7/36) and hyperoxaluria (13.9 percent; 5/36). There was no significant difference in age or sex between the groups with and without metabolic abnormality. Conclusions: Most patients with recurrent lithiasic pathology or at high-risk display one or more metabolic disorders, being hypercalciuria and hypocitraturia the most frecuently encountered. In this study, there was no difference between sexes in most of the metabolic disorders, nor in its age distribution. These results demonstrate the need for metabolic studies in high-risk patients, since there are tools that allow therapeutic medical management of metabolic disorders and thus reduce the recurrence of lithiasis.