Metabolic syndrome in obese adolescents is associated with risk for nephrolithiasis

Effect of age, BMI, and gender on urinary risk factors in pediatric idiopathic stone formers

INTRODUCTION

The incidence of pediatric urolithiasis has been increasing over the years; however, the etiology of this increase is not well understood. Age, body mass index, and gender have been examined as possible risk factors for stone disease, but with inconsistent and variable associations.

OBJECTIVE

We aim to investigate the urine chemistry factors, as assessed by 24-h urinary parameters, in pediatric stone formers at a large volume tertiary referral center in the highest areas in the United States, the Southeast, based on age, body mass index, and gender.

STUDY DESIGN

We retrospectively reviewed all pediatric stone formers who completed a 24-h study between 2005 and 2016. Patients were stratified by age (3-10 versus 11-18 years of age), overweight status (above versus below the 85th percentile for body mass index), and gender (male versus female) (Summary Figure). Statistical analysis included analysis of variance and logistic regression.

RESULTS

243 patients were included in our analysis. Patients in the first decade of life were found to have greater numbers of urinary risk factors than those in the second decade. Non-overweight patients were more likely to have hyperoxaluria and hyperuricosuria, while overweight patients were more likely to have hypocitraturia. Female patients were more likely to have higher hyperoxaluria, while male patients were more likely to have hypercalciuria.

DISCUSSION

In contrast to prior publications, obesity is not linked to increased risk of urolithiasis with non-overweight individuals having a greater number of risk factors than the overweight cohort. Despite stone disease being more prevalent in adolescents, the greatest number of risk factors were present in the first decade of life. Lastly, female children had more urinary risk factors than males. Further understanding of the underlying causes of stone disease in various pediatric populations is warranted.

CONCLUSION

While more urinary risk factors were identified in younger, non-overweight, and female patients, there remains no consensus on the urinary risk factors for pediatric urolithiasis. Further study is needed to elucidate the risk factors and pathophysiology of pediatric stone disease.

The Relationship Between Nephrolithiasis Risk with Body Fat Measured by Body Composition Analyzer in Obese People

BACKGROUND

Nephrolithiasis (kidney stones) continues to be a major cause of morbidity and healthcare spending that visceral and subcutaneous adipose tissue may associate with kidney stone formation. This study aimed to investigate the relationship between nephrolithiasis with visceral fat scale in obese people in Western Iran for the first time.

MATERIALS AND METHODS

In 2017, 103 participants with BMI≥30 kg/m² were selected for the present study. The participants were divided into two groups, 52 as case group (having the kidney stone) and 58 as healthy control group (no kidney stone or history of the kidney stone or any other disease). The levels of body composition were checked by body composition analyzer (BoCA x1) based on Bio Impedance mechanism.

RESULTS

Two groups were matched in terms of sex and BMI. There was a significant difference between two groups for the visceral fat to subcutaneous fat ratio (VSR) that accordingly, the mean VSR in the case group was higher than the control group. The difference for other variables between two groups was not significant.

CONCLUSIONS

The results showed that visceral and subcutaneous fat and VSR were important risk factors for kidney stone formation (nephrolithiasis). Evaluating these fats in stone formers may facilitate a tailored metabolic evaluation and treatment plan.

Dyslipidaemia in overweight children and adolescents is associated with an increased risk of kidney stones

AIM

There is conflicting evidence about the role of obesity in paediatric nephrolithiasis. This Polish study explored the influence of nutritional status and lipid disturbances on urinary lithogenic factors and the risk of kidney stone formation in children and adolescents from three to 18 years of age.

METHODS

We carried out serum lipid profile evaluations and 24-h urine chemistry analyses on 493 overweight/obese paediatric participants (mean age 13 years) without nephrolithiasis and 492 healthy normal weight sex and age-matched controls.

RESULTS

A third (33%) of the study group had blood lipid disturbances, with more acidic urine, lower urinary citrate excretion and a higher fraction of ionised calcium and higher Bonn Risk Index than the controls. The participants' body mass index standard deviation score (BMI Z-score) was positively correlated with urinary oxalate and uric acid and negatively correlated with citrate excretion. Total cholesterol, low-density lipoprotein cholesterol and triglycerides correlated negatively with citraturia, while high-density lipoprotein cholesterol correlated positively.

CONCLUSION

The main factor that predisposed overweight and obese children to kidney stones was hypocitraturia. Urinary citrate excretion was related to both BMI Z-scores and all lipid fraction abnormalities. However, hypercholesterolaemia and particularly low-density lipoprotein hypercholesterolaemia seemed to play a major role.

Factors Associated With the Lower Prevalence of Nephrolithiasis in Children Compared With Adults

OBJECTIVE

To determine the reasons behind the lower prevalence of kidney stones in children by assessing urinary lithogenic parameters in healthy children, healthy adults, and 3 groups of stone-former patients.

METHODS

The study subjects included 75 healthy adults, 105 healthy children, 62 patients with previous calcium oxalate monohydrate papillary stones, 120 patients with previous calcium oxalate monohydrate unattached stones, and 248 patients with previous calcium oxalate dihydrate stones. Twenty-four-hour urine samples were collected, and the urinary lithogenic parameters were measured.

RESULTS

Calcium, magnesium, and phosphorous concentration differed significantly between healthy children and adults. Except citrate, all solute/creatinine ratios differed between healthy children and adults. However, these differences were much more important in the cases of calcium and magnesium. The calcium/creatinine ratio was 2-fold lower, whereas the magnesium/creatinine ratio was 2-fold higher, in healthy children than that in healthy adults (P <.001 each). The calcium/creatinine ratio was higher and the citrate/creatinine ratio lower in calcium oxalate dihydrate stone formers than that in healthy adults.

CONCLUSION

Ratios of calcium and magnesium to creatinine, as well as morphoanatomic factors and lifestyle habits, may explain the lower prevalence of nephrolithiasis in children than those in adults.

Metabolic syndrome and nephrolithiasis: a systematic review and meta-analysis of the scientific evidence

The metabolic syndrome is a cluster of cardiometabolic alterations at least partly dependent on reduced insulin sensitivity and hyperinsulinemia that can have several renal implications. A systematic review and meta-analysis of studies available in the international literature in English language demonstrates that the metabolic syndrome occurrence is associated with a significantly higher prevalence of nephrolithiasis (odds ratio 1.29, 95% confidence intervals: 1.11-1.51). The pathophysiological bases of this association are currently not completely understood, however. Potential pathogenetic links between the two conditions include metabolic factors that promote insulin resistance as well as stone formation in urine, environmental factors such as diet, oxidative stress and inflammation, and molecular changes impacting the transport of some analytes in urine. Metabolic syndrome-related nephrolithiasis shows peculiar clinical and biochemical characteristics and should be considered a multifactorial systemic disorder needing a multidisciplinary approach for adequate prevention and management in pediatric and adult age.

Calcium oxalate supersaturation increases early after Roux-en-Y gastric bypass

BACKGROUND

Calcium oxalate (CaOx) nephrolithiasis is an adverse effect of Roux-en-Y gastric bypass surgery (RYGB). It is unknown when the increased risk for CaOx stone formation occurs after surgery.

METHODS

We studied 13 morbidly obese adults undergoing RYGB with 24-hour urine collections at 4 weeks before and 1, 2, 4, and 6 months after surgery and computed CaOx relative saturation ratio (RSR) by EQUIL2.

RESULTS

Eleven patients were female, mean ± standard deviation age was 41.1 ± 7.2 years, and none had diabetes or chronic kidney disease. Median (interquartile range) urinary oxalate excretion increased linearly from 12.6 (10.9-37.9) mg/24 hr at baseline to 28.4 (14.4-44.0) mg/24 hr at 6 months (slope = .188; P = .005). CaOx RSR increased significantly at 2 months after RYGB (1.4 [1.2-2.4] to 4.9 [1.7-10.0]; P = .017) and rose throughout the study to 5.7 (3.7-12.2) at 6 months (P = .001) with a positive linear slope (.255; P = .001). One patient had critical CaOx supersaturation (RSR = 34.7) and severe hyperoxaluria (101.7 mg/24 hr) at 6 months after RYGB. Significant decreases over time were seen in urine volume and sodium and potassium excretion, but no changes were noted in urinary pH, calcium, magnesium, or citrate.

CONCLUSIONS

Our data suggest that CaOx RSR, and thus risk for nephrolithiasis, rises as early as 2 months after RYGB and increases gradually in the first 6 months, largely because of reduced urine volume and increased urinary oxalate excretion. Interventions to reduce CaOx RSR, such as adequate fluid intake and agents to bind enteric oxalate, need to be evaluated in patients at risk for nephrolithiasis after RYGB.

Changing stone composition profile of children with nephrolithiasis

OBJECTIVE

To determine if this trend toward calcium phosphate stone formation exists in children.

METHODS

This is a retrospective study of medical records of 179 children managed at our medical center from 1992-2010 for whom stone analysis and other pertinent laboratory data were available. A comparison of patients managed from 1992-2000 (P1) and 2001-2010 (P2) was undertaken. Statistical analysis included nonparametric tests.

RESULTS

There were no significant differences in the mean age of the 2 cohorts. During both periods, boys comprised a significantly higher proportion during the first decade of life, whereas girls comprised a significantly higher proportion during the second decade. A higher percentage of patients had calcium oxalate (CaOx) stones in P1 compared to P2 (60% vs 47%, P = .0019). There was a significant increase in the percentage of patients having calcium phosphate stones in P2 compared to P1 (27% vs 18.5%, P = .008). Twenty-seven patients had recurrent stones. A comparison of the compositions of the first and last stones of patients within this group demonstrated an increasing proportion of brushite stones (3.7% vs 11.1%, P = .04). Twenty-four hour urine testing results were similar for those with CaOx and calcium phosphate stones.

CONCLUSION

An increasing proportion of children have calcium phosphate calculi. Brushite stones are more prevalent in children with recurrent stone events. The impetus of these shifts is not readily apparent.

Multidisciplinary therapy reduces risk factors for metabolic syndrome in obese adolescents

This study aims to assess the effects of a 16-week multidisciplinary program of obesity treatment on the control of metabolic syndrome (MS) and dyslipidemia in obese adolescents. Eighty-six adolescents aged 10-18 years were allocated in either the intervention group (IG; n = 44) or control group (CG; n = 42). IG was submitted to a multidisciplinary intervention based on cognitive behavioral therapy that aimed to modify eating habits and exercise behavior. We analyzed, before and after the intervention period, anthropometric parameters, body composition, bone mineral density, cardiorespiratory fitness, blood pressure, glucose, insulin, and lipid profile of the subjects. MS was classified according to International Diabetes Federation (2007) and the presence of dyslipidemia according to Back et al. (Arq Bras Cardiol 85:4-36, 2005). In the beginning of the intervention, the median number (range) of risk factors for MS present was 2.0 (0.0-5.0) in the IG and 2.0 (0.0-4.0) in the CG. After the intervention, this parameter reduced significantly in the IG (1.0 (0.0-5.0); p = 0.004) while no change was observed in the CG (2.0 (0.0-4.0); p = 0.349). In addition, we observed improvements in body mass index, waist circumference, hip circumference, maximal oxygen uptake, absolute and relative body fat, systolic blood pressure, diastolic blood pressure, and total cholesterol in the IG which was not identified in the CG. Conclusio n: We suggest that a 16-week multidisciplinary intervention based on cognitive behavioral therapy was adequate to reduce risk factors for MS in obese adolescents.

Correlation of metabolic syndrome with urinary stone composition

OBJECTIVE

To determine the correlation between metabolic syndrome and the distribution of stone components in patients with urolithiasis.

METHODS

Between January 2007 and December 2010, renal or ureteral stones were collected from 712 patients (432 males, 280 females) who underwent surgical intervention at three hospitals in South Korea. Metabolic syndrome was defined according to the latest definition of the International Diabetes Federation, using ethnicity- and sex-specific cut-off values for central obesity. Patients were assessed by factors used in metabolic syndrome. All urinary stones were analyzed using infrared spectrophotometry and categorized according to their main component.

RESULTS

The patients' mean age was 55.9 years (range 19-93 years). Of the 712 patients, 347 (48.7%; 205 males, 142 females) had a diagnosis of metabolic syndrome. Calcium oxalate (71.5%), uric acid (15.3%), carbonate apatite (8.0%) and struvite (4.1%) calculi were found as the main stone components. Overall, the proportion of uric acid calculi was markedly higher in patients with rather than without metabolic syndrome (19.6 vs 11.2%; P=0.002). However, the proportion of calcium oxalate, carbonate apatite and struvite calculi did not differ between the two groups. The multivariable-adjusted odds ratio for uric acid calculi according to the metabolic syndrome components indicated that the presence of metabolic syndrome was associated with a 93% increased odds ratio of uric acid calculi compared with the absence of metabolic syndrome. Impaired fasting glucose and hypertriglyceridemia were independent risk factors for uric acid calculi.

CONCLUSIONS

Metabolic syndrome is associated with a significantly increased risk of uric acid calculi development, especially those with impaired fasting glucose and hypertriglyceridemia.