Serum uric acid in U.S. adolescents: distribution and relationship to demographic characteristics and cardiovascular risk factors

[Comparison of serum uric acid and liver enzyme levels in adolescents with obesity and with metabolic syndrome]

INTRODUCTION

a relationship has been observed between elevated levels of liver enzymes and uric acid with the presence of metabolic syndrome (MS) in the pediatric population.

OBJECTIVE

to compare serum liver enzyme and uric acid levels between adolescents with and without MS.

METHODS

a cross-sectional study was carried out in adolescents with obesity between 10 and 18 years old. Somatometric data, serum insulin, lipid profile, uric acid levels and liver enzymes (aspartate aminotransferase [AST], alanine aminotransferase [ALT] and gamma-glutamyl transferase [GGT]) were analyzed.

STATISTICAL ANALYSIS

Student's t test or the Chi-square test was used to evaluate differences between groups.

RESULTS

a total of 1095 adolescents with obesity were included (444 with MS and 651 without MS). The group with MS had a higher BMI (with MS 2.28 vs without MS 2.11 p < 0.001), with no difference in body fat (42.9 % vs 42.9 %, p = 0.978). The MS group had significantly higher levels of AST (34.4 vs. 29.5, p = 0.013), ALT (42.2 vs. 34.6, p = 0.003), and uric acid (6.17 vs. 5.74, p = 0.002). comparison to the group without MS. The proportion of ALT (40.5 % vs 29.5 %, p = 0.029) and altered uric acid (58.1 % vs. 45.6 %, p = 0.019) was higher in the MS group.

CONCLUSIONS

serum levels of ALT, AST and uric acid in adolescents with obesity and MS were higher compared to those without MS. Altered ALT was a risk factor for SM.

Association of serum uric acid Levels with metabolic syndromes in Korean adolescents

Introduction

The study findings investigated uric acid reference values and their association with a cluster of cardiometabolic risk factors among adolescents using the Korea National Health and Nutrition Examination Survey (KNHANES).

Methods

A retrospective cross-sectional study was conducted using the KNHANES database from 2016 to 2018, involving a total of 2,462 participants aged between 10 and 18 years. Based on age- and sex-specific percentile curves for serum uric acid (SUA) levels from the KNHANES, we examined the correlation between cardiometabolic risk factors and serum uric acid levels.

Results

The percentile values of SUA varied with sex and age. In male subjects, SUA levels tended to increase from 10 to 14 years of age and plateaued after 14 years of age. Moreover, the overall uric acid level in females was found to be lower than that in males; the levels tended to increase at approximately 10 to 12 years old but were relatively consistent according to age. Mean uric acid levels increased according to obesity status in both males and females. However, correlation analysis revealed that SUA levels were associated with several metabolic risks even after adjusting for obesity. The detailed metabolic syndrome (MetS) components that were observed to be associated with an increase in uric acid levels were different between males and females, but overall, high uric acid levels increased MetS risk. Additionally, a significant increase in MetS-related odds ratio (OR) for components, including waist circumference (WC), triglyceride (TG) levels, and low high-density lipoprotein cholesterol (HDL-c), was observed. However, differences between sexes were apparent, with a more pronounced increase in OR based on SUA levels in girls.

Discussion

SUA levels were closely associated with MetS and its components, even in nonobese subjects. Therefore, high SUA levels in children and young adolescents should be closely monitored to prevent MetS.

Association Between Dietary Fiber Intake and Cardiometabolic Risk Factors in Adolescents in the United States

OBJECTIVE

To determine the association between dietary fiber intake and markers of cardiometabolic risk in adolescents, with blood pressure (BP) as the primary outcome of interest and secondary outcome measures including other established markers of childhood cardiometabolic risk, such as obesity, lipids, albuminuria, estimated glomerular filtration rate (eGFR), and uric acid.

STUDY DESIGN

Dietary fiber intake was assessed by two 24-hour dietary recall interviews, which were averaged and corrected for body weight. Logistic and linear regression models were used to analyze the cross-sectional association between dietary fiber and cardiometabolic markers. Participants aged 13-17 years in the National Health and Nutritional Examination Survey 2009-2018 who completed a 24-hour dietary recall survey were included. Exclusion criteria included pregnancy, small for gestational age status, and history of major health comorbidities.

RESULTS

In fully adjusted regression models, low dietary fiber intake was significantly associated with greater diastolic blood pressure (β = -13.29; 95% CI, -20.66 to -5.93), body mass index z-score (β = -0.91; 95% CI, -1.47 to -0.34), and uric acid (β = -0.80; 95% CI, -1.44 to -0.16).

CONCLUSIONS

The association found between low dietary fiber intake and poor childhood cardiometabolic risk markers indicate a need for prospective studies using fiber intake as a dietary intervention in childhood and as a tool for prevention of many chronic conditions.

Trends in serum uric acid levels among Korean children and adolescents between 2016 and 2020: a nationwide study

The aim of this study was to examine trends in serum uric acid (SUA) levels over a recent 5-year period according to age, sex, obesity, and abdominal obesity among Korean children and adolescents. We conducted a serial cross-sectional analysis using nationally representative data from the Korea National Health and Nutritional Examination Survey from 2016 to 2020. The study outcome was trends in SUA levels. SUA trends were analyzed by survey-weighted linear regression analysis considering the survey year as a continuous variable. SUA trends were also analyzed for subgroups based on age, sex, abdominal obesity, or obesity. This study included 3,554 children and adolescents aged 10-18 years. SUA increased significantly over the study period in boys (p for trend = 0.043), but not in girls (p for trend = 0.300). In age-specific analyses, SUA increased significantly in the 10-12 years group (p for trend = 0.029). After adjusting for age, SUA increased significantly in the obese group of both boys (p for trend = 0.026) and girls (p for trend = 0.023), but not in the overweight, normal, or under-weight groups of either sex. After adjusting for age, SUA increased significantly in the abdominal obesity group of boys (p for trend = 0.017) and girls (p for trend = 0.014), but not in the non-abdominal obesity group of either sex.   Conclusion: In the current study, SUA levels significantly increased in both boys and girls with obesity or abdominal obesity. Further studies of the effect of SUA on health outcomes in boys and girls with obesity or abdominal obesity are needed. What is Known: • High serum uric acid (SUA) is a risk factor for various metabolic diseases, including gout, hypertension, and type 2 diabetes. What is New: • SUA levels increased in boys and the 10-12 years group of Korean children and adolescents. • SUA levels increased significantly in Korean children and adolescents with obesity or central obesity.

Association between Dietary Fiber Intake and Hyperuricemia among Chinese Adults: Analysis of the China Adult Chronic Disease and Nutrition Surveillance (2015)

This study aimed to assess the association of dietary fiber intake with serum uric acid (SUA) levels and risk of hyperuricemia (HUA) among Chinese adults using the latest nationally representative data. A total of 66,427 Chinese adults aged 18 years and over from the China Adult Chronic Disease and Nutrition Surveillance in 2015 were included in this study. Dietary intakes were measured with a 3-day 24 h dietary recall and the household condiment weighing method. Mixed-effect linear and logistic regression models were used to evaluate the associations of dietary fiber intake with SUA levels and risk of HUA, respectively. Compared to the lowest intake group, the coefficient and 95% confidence in the highest intake group of total fiber were −0.06 (−0.08, −0.04) (p-trend < 0.001), −0.18 (−0.2, −0.16) (p-trend < 0.001) for cereal fiber, 0.03 (0.01, 0.04) (p-trend = 0.051) for legume fiber, 0 (−0.01, 0.02) (p-trend = 0.869) for vegetable fiber and 0.01 (−0.001, 0.04) (p-trend = 0.296) for fruit fiber. The odds ratio (OR) and 95% confidence interval (CI) of HUA for the highest vs. lowest intake group of total fiber were 0.88 (0.84, 0.91) (p-trend = 0.001), 0.67 (0.63, 0.71) (p-trend < 0.001) for cereal fiber, 1.05 (1, 1.09) (p-trend = 0.248) for legume fiber, 1.01 (0.97, 1.05) (p-trend = 0.982) for vegetable fiber and 1.06 (1, 1.12) (p-trend = 0.264) for fruit fiber. Our findings suggest that consumption of total fiber and cereal fiber were significantly inversely associated with SUA levels and HUA risk among the Chinese adult population. Developing and implementing effective public education programs are urgently needed to increase the intake of dietary fiber, especially cereal fiber among Chinese adults.

Hyperuricemia, Elevated Body Mass Index, Female Sex, and Albuminuria Increase the Probability of Elevated High-Sensitivity C-Reactive Protein: Results From the National Health and Nutrition Examination Survey 2015-2018

Importance: High uric acid (UA) is hypothesized to worsen kidney and cardiovascular disease morbidity via activation of systemic inflammation. Clinical trials of UA modification report reduction of the inflammatory marker high sensitivity C-reactive protein (hs-CRP) as an outcome measure, but studies have not demonstrated that hyperuricemia independently increases hs-CRP when adjusted for important confounders such as body mass index (BMI), sex, and age. Objective: To identify clinical risk factors for elevated hs-CRP, including but not limited to hyperuricemia, through a cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) 2015-2018. Results: In the final multivariate logistic regression model, the exposure with the strongest effect on the odds of elevated hs-CRP was BMI in the fourth quartile, OR = 13.1 (95% CI 6.25-27.42), followed by female sex (OR = 4.9, 95% CI 2.92-8.34), hyperuricemia (OR = 2.2, 95% CI 1.36-3.45), urine albumin creatinine ratio (ACR; OR = 1.5, 95% CI 1.09-2.18), poor overall health (OR = 1.4, 95% CI 1.18-1.58), and interactions between hyperuricemia and sex (OR = 1.4, 95% CI 1.05-1.83), and between BMI and sex (OR = 1.2, 95% CI 1.03-1.47). Notably, chronic kidney disease (CKD) and CKD surrogates were not associated with hs-CRP despite urine ACR maintaining a significant independent effect. Conclusions: In this national population-based study, we demonstrated that hyperuricemia significantly increases the odds of elevated hs-CRP, independent from BMI, female sex, urine ACR, and overall health status. Further study is recommended to better understand the sex difference in this association and the role of albuminuria, but not CKD, in systemic inflammation.

The relationship between anthropometric factors and hyperuricemia in adolescent athletes

PURPOSE

Hyperuricemia has been increasingly prevalent and linked to future cardio-metabolic risks in adolescent population. The study aims to explore the relationship between anthropometric indices and hyperuricemia among adolescent athletes.

METHODS

This was a cross-sectional study of 387 student athletes (218 males and 169 females; mean age, 17.4 ± 1.3 years) in Northern Taiwan in 2013-2015. We exhibited the prevalence of hyperuricemia among this population, and tested the association of serum uric acid levels with different anthropometric parameters in males and females respectively.

RESULTS

A total of 59 (27.1%) male and 37 (21.8%) female adolescent athletes had hyperuricemia. Both in male and female adolescents, several obesity-related anthropometric parameters were significantly higher in hyperuricemia groups than in non-hyperuricemia groups. The odds of having hyperuricemia significantly increased with increasing BMI, BMI z-score, waist circumference and waist-to-height ratio in logistic regression analysis. There was a U-shaped association between uric acid level and body fat percentage (BF%) in both genders. Subjects whose BF% in lowest-body-fat-percentage quintile (quintile 1) and highest-body-fat-percentage quintile (quintile 5) had higher mean serum uric acid level than subjects whose BF% in the middle three quintiles. In both genders, the odds ratio (OR) of having hyperuricemia in subjects whose BF% in quintile 1 remained significantly higher than the OR in the middle three quintiles (the reference) after adjusting for age and BMI z-score.

CONCLUSIONS

In addition to the positive association between obesity and hyperuricemia, there is a U shape association between BF% and prevalence of hyperuricemia among adolescent athletes of both genders.

Association of uric acid with cardiovascular risk in Brazilian children and adolescents

BACKGROUND AND AIM

Hyperuricemia in adults is associated with cardiovascular risk factors. However, there is less data regarding this association in children and adolescents. Our purpose was to determine association between serum uric acid (SUA) and cardiovascular risk.

METHODS AND RESULTS

A fasting blood sample was collected from 1750 participants aged 6-17 years enrolled in a social project and public schools in Espírito Santo, Brazil. Internal cut-offs were generated to define high SUA (≥90th percentile of SUA concentration for sex and age group). Body mass index percentile (pBMI), body fat percentage (BFP) and muscle mass were determined by bioimpedance. Data are given as mean ± standard deviation. High SUA was associated with overweight/obesity (OR 3.7 CI 95% 2.7-5.0), high waist circumference (WC) (OR 3.9 CI 95% 2.9-5.4), low HDL (OR 2.0 CI 95% 1.5-2.8), high blood pressure (BP) (OR 1.8 CI 95% 1.1-3.2), high BFP (OR 4.1 CI 95% 2.7-6.4), metabolic syndrome (MetS) (OR 3.6 CI 95% 1.8-7.1) and insulin resistance (OR 1.7 CI 95% 1.1-2.7). Individuals in the fourth quartile of SUA, compared to those in the first quartile, showed higher age, pBMI, WC, BFP and muscle mass. Using a reference value of 5.5 mg/dL, the prevalence of hyperuricemia in the sample was 10.3% (CI 95% 8.9-11.7%).

CONCLUSION

Higher SUA values are associated with higher cardiovascular risk in childhood and adolescence. The main cardiovascular risk factors associated with hyperuricemia were overweight/obesity, high WC, dyslipidemia, high BFP, high BP, insulin resistance and MetS.

Serum uric acid and blood pressure among adolescents: data from the Nutrition and Health Survey in Taiwan (NAHSIT) 2010-2011

PURPOSE

Elevated serum uric acid (UA) is frequently observed in adults with high blood pressure (BP); however, data from adolescents are limited. We examined the association between serum UA and BP in a nationally representative sample of Taiwan adolescents.

MATERIAL AND METHODS

Some 1384 participants, aged 14-19 years, from the Nutrition and Health Survey in Taiwan 2010-2011 were included for the study. Elevated BP was defined as systolic or diastolic BP ≥120/80 mmHg. The analyses examined the relationship between serum UA and BP using linear regression and odds ratios of having an elevated BP using logistic regression.

RESULTS

In this study population, the mean age was 16.0 years, mean serum UA was 5.8 mg/dL, 22.5% were obese (body mass index ≥24 kg/m²) and 9.8% had an elevated BP. Compared to girls, boys are more likely to be obese and to have higher serum UA and BP. After full adjustments, systolic BP, diastolic BP and mean arterial pressure increased 0.45, 0.48 and 0.47 mmHg, respectively, for each 1-mg/dL increase in UA (p = 0.07, 0.03 and 0.02, respectively). The odds of having an elevated BP were 3.4 times higher in subjects of the upper tertile of serum UA than those of the lower tertile (p = 0.02).

CONCLUSION

Adolescents with factors as male, obesity, and UA ≥5.5 mg/dL were prone to have an elevated BP, regardless of age and family history of hypertension. The present study found that serum UA levels are significantly correlated to BP in Taiwanese adolescents.

Serum uric acid in Korean children and adolescents: reference percentiles and association with metabolic syndrome

PURPOSE

To establish age/sex-specific reference intervals for serum uric acid and to examine the associations between serum uric acid level and metabolic syndrome (MetS) and its components in Korean children and adolescents.

METHODS

We analyzed data for 1,349 subjects aged 10 to 19 years from the Korea National Health and Nutrition Examination Survey 2016-2017.

RESULTS

The mean uric acid levels were 5.9±1.3 mg/dL (interquartile range, 5.0-6.8 mg/dL) in males and 4.6±0.9 mg/dL (interquartile range, 3.9-5.2 mg/dL) in females. The mean uric acid level increased significantly from 10-13 years of age in males, but not in females. The overall prevalence of MetS was 5.9% (7.3% in males and 4.3% in females; P=0.022). The prevalences of MetS in the lowest, second, third, and highest quartiles of uric acid level were 4.4%, 3.3%, 6.1%, and 15.2%, respectively, in males (P for trend &lt;0.001) and 1.9%, 0.0%, 4.1%, and 10.9%, respectively, in females (P for trend &lt;0.001). Compared with the lowest quartile of uric acid level, the odds ratio (with 95% confidence interval) for MetS in the highest quartile was 2.897 (1.140-7.361) in males and 5.173 (1.459-18.342) in females. Subjects in the highest quartile exhibited increased risk for abdominal obesity and low high-density lipoprotein cholesterol in both sexes.

CONCLUSION

Serum uric acid level is positively associated with MetS and its components abdominal obesity and low high-density lipoprotein cholesterol.

Hyperuricemia is associated with a lower glomerular filtration rate in pediatric sickle cell disease patients

BACKGROUND

Sickle cell nephropathy (SCN) is a progressive disease that contributes significant morbidity and mortality in sickle cell disease (SCD), yet it remains poorly understood. Hyperuricemia negatively impacts renal function in the non-sickle cell population but is understudied in SCD.

METHODS

We performed a cross-sectional analysis of the first 78 pediatric SCD patients enrolled in a cohort study. The mechanism of development of hyperuricemia (defined, serum uric acid (UA) ≥ 5.5 mg/dL) was characterized as a result of either UA overproduction or inefficient renal excretion by the Simkin index and fractional clearance of urate (FCU) equations. Associations between hyperuricemia and albuminuria or estimated glomerular filtration rate (eGFR) were determined by linear regression.

RESULTS

The prevalence of hyperuricemia in this young population (mean age 11.6 ± 3.77 years) was 34.2%. Only 1 hyperuricemic participant overproduced UA by Simkin index, while 62.5% were inefficient renal excretors of UA (FCU < 4%). Hyperuricemia was associated with a significant decrease in average eGFR, -27 ml/min/1.73m² below normouricemia (mean eGFR 151.6 ± 40.32), p = 0.0122. Notably, the previously accepted association between decline of eGFR with age is significantly modified by hyperuricemia stratification, where hyperuricemia explains 44% of the variance in eGFR by age (R² = 0.44, p = 0.0004) and is nonsignificant in normouricemia (R² = 0.07, p = 0.0775).

CONCLUSION

These findings indicate that hyperuricemia may be associated with early eGFR decline in SCN. This association must be further characterized in prospective cohort studies in SCN, and hyperuricemia must be investigated as a potential therapeutic target for SCN.

Prevalence of hyperuricemia and its association with metabolic syndrome and cardiometabolic risk factors in Korean children and adolescents: analysis based on the 2016-2017 Korea National Health and Nutrition Examination Survey

Purpose

Investigating the prevalence of hyperuricemia and its association with metabolic syndrome (MetS) and cardiometabolic risk factors (CMRFs) in Korean children and adolescents.

Methods

This cross-sectional survey used data from the 7th Korea National Health and Nutrition Examination Survey (2016–2017); 1,256 males and females aged 10–18 years were included. Hyperuricemia was defined as serum uric acid levels were >6.6 mg/dL at 10–11 years of age (both sexes), >7.7 mg/dL for males at 12–18 years of age and >5.7 mg/dL for females at 12–18 years of age. MetS was defined by the International Diabetes Federation criteria. Logistic regression analysis was used to analyze hyperuricemia-associated risk factors.

Results

The prevalence of hyperuricemia was 9.4% (male, 8.4%; female, 10.5%) (P<0.281). After adjusting for sociodemographic factors and health behaviors in multivariate analysis (model 1), the odds ratio (OR) for hyperuricemia of MetS was 3.05 (95% confidence interval [CI], 1.17–7.92; P=0.022). After adjusting for the same variables in model 1 plus obesity and all MetS components (model 2), only abdominal obesity was significant, and the OR for hyperuricemia was 3.38 (95% CI, 1.72–6.63; P<0.001) After adjusting for the same variables in model 1 plus body mass index (BMI) z scores and all MetS components except abdominal obesity (model 3), only BMI z scores was significant, and the OR for hyperuricemia was 1.59 (95% CI, 1.34–1.89; P<0.001).

Conclusion

MetS, abdominal obesity, and BMI z scores were CMRFs significantly associated with hyperuricemia in Korean children and adolescents. Therefore, attention should be paid to hyperuricemia in patients with obesity or MetS.

Hyperuricemia in Children and Adolescents: Present Knowledge and Future Directions

Recent evidence suggests that hyperuricemia is an important condition in children and adolescents, particularly in association with noncommunicable diseases. This review aims to summarize our current understanding of this condition in pediatric patients. An analysis of serum uric acid reference values in a healthy population indicates that they increase gradually with age until adolescence, with differences between the sexes arising at about 12 years of age. This information should be taken into consideration when defining hyperuricemia in studies. Gout is extremely rare in children and adolescents, and most patients with gout have an underlying disease. The major causes of hyperuricemia are chronic conditions, including Down syndrome, metabolic or genetic disease, and congenital heart disease, and acute conditions, including gastroenteritis, bronchial asthma (hypoxia), malignant disorders, and drug side effects. The mechanisms underlying the associations between these diseases and hyperuricemia are discussed, together with recent genetic information. Obesity is a major cause of hyperuricemia in otherwise healthy children and adolescents. Obesity is often accompanied by metabolic syndrome; hyperuricemia in obese children and adolescents is associated with the components of metabolic syndrome and noncommunicable diseases, including hypertension, insulin resistance, dyslipidemia, and chronic kidney disease. Finally, strategies for the treatment of hyperuricemia, including lifestyle intervention and drug administration, are presented.

Beneficial Effect of Dietary Fiber on Hyperuricemia in Rats and Humans: A Review

Hyperuricemia is recognized as a lifestyle-related disease and the prevalence is increasing in many parts of the world. Excessive intake of purines increases serum uric acid concentration and is thought to be one factor causative of hyperuricemia. Therefore, it is thought that prevention of hyperuricemia by dietary control may be very important. This is an article of our basic research regarding the role of dietary fiber in the suppression of hyperuricemia induced by dietary purines in rats; in addition, clinical research suggesting the possibility that dietary fiber intake has a beneficial effect on the prevention or suppression of hyperuricemia in humans is discussed. Our own studies reveal that the test dietary fiber significantly suppresses the elevation of serum uric acid concentration induced by dietary RNA (12.3-46.2%), adenosine-5'-monophosphate (9.5-23.2%), adenosine (10.7-20.4%), or adenine (16.3-38.9%) and suppresses experimental hyperuricemia in rats. The mechanism is presumed to be mediated by suppression of the digestion and/or absorption of dietary purines by dietary fiber. In clinical studies, intake of dietary fiber decreases serum uric acid concentrations. Reports of recent epidemiological studies indicate that higher levels of hyperuricemia increase the prevalence of its comorbidities (e.g., chronic kidney disease, obesity, hypertension, diabetes, and cardiovascular disease) and dietary fiber intake is associated with significantly lower risk for hyperuricemia and its comorbidities. We wish to emphasize the importance of recognizing the validity of increased dietary fiber intake as a preventive or suppressive method for hyperuricemia and its comorbidities.

Association between the antioxidant uric acid and depression and antidepressant medication use in 96 989 individuals

OBJECTIVE

In the last decade, several studies have suggested that depression is accompanied by increased oxidative stress and decreased antioxidant defenses. We tested the hypothesis that high levels of the antioxidant uric acid are associated with lower risk of hospitalization with depression and use of prescription antidepressant medication.

METHOD

We examined plasma levels of the antioxidant uric acid in 96 989 individuals from two independent cohort studies. Logistic regression and Cox proportional hazards regression models were multivariable adjusted for age, gender, alcohol, smoking, income, body mass index, C-reactive protein, hemoglobin, triglycerides, cardiovascular disease, diabetes, and intake of meat and vegetables. Results were performed separately in each study and combined in a meta-analysis.

RESULTS

In both studies, high uric acid was associated with lower risk of hospitalization as in-patient or out-patient with depression and antidepressant medication use. A doubling in uric acid was associated with an effect estimate of 0.57 (95% CI 0.49-0.65) and 0.77 (0.73-0.81) for hospitalization with depression and antidepressant medication use. The association was consistent across strata of all covariates. Results were attenuated in Cox regression analyses with less statistical power.

CONCLUSION

High plasma levels of uric acid were associated with low risk of depression hospitalization and antidepressant medication use.

Clinical Practice Guideline for Screening and Management of High Blood Pressure in Children and Adolescents

These pediatric hypertension guidelines are an update to the 2004 "Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents." Significant changes in these guidelines include (1) the replacement of the term "prehypertension" with the term "elevated blood pressure," (2) new normative pediatric blood pressure (BP) tables based on normal-weight children, (3) a simplified screening table for identifying BPs needing further evaluation, (4) a simplified BP classification in adolescents ≥13 years of age that aligns with the forthcoming American Heart Association and American College of Cardiology adult BP guidelines, (5) a more limited recommendation to perform screening BP measurements only at preventive care visits, (6) streamlined recommendations on the initial evaluation and management of abnormal BPs, (7) an expanded role for ambulatory BP monitoring in the diagnosis and management of pediatric hypertension, and (8) revised recommendations on when to perform echocardiography in the evaluation of newly diagnosed hypertensive pediatric patients (generally only before medication initiation), along with a revised definition of left ventricular hypertrophy. These guidelines include 30 Key Action Statements and 27 additional recommendations derived from a comprehensive review of almost 15 000 published articles between January 2004 and July 2016. Each Key Action Statement includes level of evidence, benefit-harm relationship, and strength of recommendation. This clinical practice guideline, endorsed by the American Heart Association, is intended to foster a patient- and family-centered approach to care, reduce unnecessary and costly medical interventions, improve patient diagnoses and outcomes, support implementation, and provide direction for future research.

Iron Supplementation Effects on Redox Status following Aseptic Skeletal Muscle Trauma in Adults and Children

Exercise-induced skeletal muscle microtrauma is characterized by loss of muscle cell integrity, marked aseptic inflammatory response, and oxidative stress. We examined if iron supplementation would alter redox status after eccentric exercise. In a randomized, double blind crossover study, that was conducted in two cycles, healthy adults (n = 14) and children (n = 11) received daily either 37 mg of elemental iron or placebo for 3 weeks prior to and up to 72 h after an acute eccentric exercise bout. Blood was drawn at baseline, before exercise, and 72 h after exercise for the assessment of iron status, creatine kinase activity (CK), and redox status. Iron supplementation at rest increased iron concentration and transferrin saturation (p < 0.01). In adults, CK activity increased at 72 h after exercise, while no changes occurred in children. Iron supplementation increased TBARS at 72 h after exercise in both adults and children; no changes occurred under placebo condition. Eccentric exercise decreased bilirubin concentration at 72 h in all groups. Iron supplementation can alter redox responses after muscle-damaging exercise in both adults and children. This could be of great importance not only for healthy exercising individuals, but also in clinical conditions which are characterized by skeletal muscle injury and inflammation, yet iron supplementation is crucial for maintaining iron homeostasis. This study was registered at Clinicaltrials.gov Identifier: NCT02374619.

Uric Acid-Induced Inflammation Is Mediated by the Parathyroid Hormone:25-Hydroxyvitamin D Ratio in Obese Adolescents

BACKGROUND

Elevated serum uric acid (SUA) level is strongly associated with prevalence of metabolic syndrome (MS), elevated parathyroid hormone (PTH) levels, and 25-hydroxyvitamin D [25(OH)D] insufficiency in adults. We examined the relationship among SUA, [25(OH)D], PTH, and inflammation in obese adolescents, in obese adolescents with and without MS.

METHODS

Body mass index, body composition, 25(OH)D, PTH, fasting lipids, glucose, high-sensitivity C-reactive protein (hs-CRP), SUA, hemoglobin A1c (HbA1c), insulin, and the homeostatic model assessment of insulin resistance (HOMA-IR) were evaluated in 152 obese adolescents.

RESULTS

Hyperuricemia [SUA ≥ 6.0 mg/dL (357 μM)] was present in 54.6% of entire cohort without significant ethnic/racial differences. While SUA was negatively correlated with high-density lipoprotein cholesterol (HDL-C) and 25(OH)D (P < 0.01), it was positively correlated with fat mass (FM), PTH, PTH:25(OH)D, and hs-CRP (P < 0.01). Vitamin D deficiency [25(OH)D <50 nM] was present in 47.4% of subjects, and PTH and 25(OH)D were inversely correlated (P < 0.0001). FM was negatively correlated with 25(OH)D (r = -0.29; P < 0.001), but was positively correlated with PTH (P < 0.0001). MS was identified in 53.3% of cohort with higher FM, SUA, hs-CRP, HOMA-IR, PTH, and PTH:25(OH)D ratio than the non-MS subgroup (P < 0.001) with similar 25(OH)D status. Multiple regression analysis showed that the PTH:25(OH)D ratio mediated the relationship between SUA and hs-CRP (β = 0.19, P < 0.05 to β = 0.15, P = 0.19).

CONCLUSIONS

Hyperuricemia is strongly associated with PTH and hs-CRP levels independent of vitamin D status. The relationship between SUA and low-grade inflammation is mediated by the PTH:25(OH)D ratio in obese adolescents.

Elevated uric acid and obesity-related cardiovascular disease risk factors among hypertensive youth

BACKGROUND

Uric acid (UA) is associated with high blood pressure in adolescents and with left ventricular hypertrophy (LVH) and cardiovascular disease (CVD) in adults. We sought to determine if UA is independently associated with CVD risk factors and left ventricular mass (LVM) over time in hypertensive youth.

METHODS

This was a 1-year prospective observational study of hypertensive children aged 3-19 years. Cross-sectional and longitudinal associations of serum UA with CVD risk factors and LVM were explored.

RESULTS

Of the 49 children who completed both the baseline and 12-month assessments, at baseline the mean age was 13.8 years and mean UA was 5.5 mg/dL; 24% had elevated UA, 51% were overweight/obese and 39% had LVH. Measures of adiposity, low high-density lipoprotein cholesterol, high-sensitivity C-reactive protein, LVM and LVH were all significantly associated with elevated UA at baseline, but not with change over time. Each 1 mg/dL increase in baseline UA was associated with a 2.5 g/m(2.7) increase in the LVM index at follow-up (95% confidence interval 0.64, 4.39; p = 0.01); after adjustment for age, sex, race, body mass index z-score, change in UA, time, blood pressure and medication use, this association was no longer significant.

CONCLUSIONS

Hypertensive children with elevated UA have a higher prevalence of obesity-related CVD risk factors. Among hypertensive children, UA may be a marker of adiposity and not an independent CVD risk factor.

Primary hypertension in childhood

There is growing concern about elevated blood pressure in children and adolescents, because of its association with the obesity epidemic. Moreover, cardiovascular function and blood pressure level are determined in childhood and track into adulthood. Primary hypertension in childhood is defined by persistent blood pressure values ≥ the 95th percentile and without a secondary cause. Preventable risk factors for elevated blood pressure in childhood are overweight, dietary habits, salt intake, sedentary lifestyle, poor sleep quality and passive smoking, whereas non-preventable risk factors include race, gender, genetic background, low birth weight, prematurity, and socioeconomic inequalities. Several different pathways are implicated in the development of primary hypertension, including obesity, insulin resistance, activation of the sympathetic nervous system, alterations in sodium homeostasis, renin-angiotensin system and altered vascular function. Prevention of adult cardiovascular disease should begin in childhood by regularly screening for high blood pressure, counseling for healthy lifestyle and avoiding preventable risk factors.