Uric acid reference values: report on 1750 healthy Brazilian children and adolescents.

BACKGROUND: Our purpose was to determine reference values and determinants of serum uric acid (SUA) in children and adolescents. METHODS: A fasting blood sample was collected from 1750 schoolchildren and adolescents (6-17 years). Puberty was defined according to the Tanner scale. Bodyweight, muscle mass, and body fat percentage were determined by bioimpedance. Data are given as cut-offs and mean ± standard deviation. RESULTS: SUA level was higher in children that had already entered puberty (4.2 ± 1.1 mg/dL) than among prepubescent (3.6 ± 0.8 mg/dL; p < 0.01). Considering the 90 percentile (p90) as the upper reference value, the following values are proposed for boys and girls, respectively: <10 years or prepubescent: ≤4.5 mg/dL and ≤4.8 mg/dL; from 10 to 13 years: ≤5.7 mg/dL and ≤5.2 mg/dL; from 14 to 17 years: ≤6.4 mg/dL and ≤5.3 mg/dL. Muscle mass explained part of the variability in SUA after pubescence, acting as an independent variable for higher levels of SUA. CONCLUSIONS: The sex, age, and phase of puberty influence SUA reference levels, and part of this influence could be explained by the higher muscle mass, mainly after the adolescence onset. IMPACT: The key message of this study is that high levels of uric acid in the blood are associated with metabolic syndrome and cardiovascular risk factors. These diseases should be prevented since the infancy However, it is necessary to establish reference values of uric acid (SUA) for children and adolescents. The Brazilian population is highly admixed and these values were not determined so far. We studied a robust sample of Brazilian schoolchildren and adolescents (6-17 years) and defined the 90th percentile of uric acid as the upper limit of normality for sex, age, and pubertal stage. These values can be used as a reference for other populations with similar characteristics.

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.

Takotsubo Cardiomyopathy in an Alzheimer Disease Patient: The Potential Contribution of Antidepressant Agents.

Takotsubo cardiomyopathy (TC) is an acute cardiac dysfunction, clinically similar to myocardial ischemia. The physiopathology of the syndrome seems to be related to excessive sympathetic activity that is triggered by physical or emotional stress factors. We report the case of an 83-year-old woman with advanced Alzheimer disease who had recently used nortriptyline and sertraline and was admitted with chest pain. An electrocardiogram showed ST-elevation, and markers of myocardial necrosis were slightly increased. However, coronariography did not demonstrate stenotic lesions. Transthoracic echocardiography and ventriculography identified decreased ventricular function, apical akinesia, and compensatory hyperkinesia of other segments that were compatible with TC. The patient evolved with cardiogenic shock and died. Alzheimer patients may be more susceptible to develop TC, both because of the disease itself and because of the multiple medications they are exposed to that increase catecholamine levels. In this case, antidepressant drugs were considered to be a potential factor that enhanced the susceptibility.