New pediatric percentiles of liver enzyme serum levels (alanine aminotransferase, aspartate aminotransferase, γ-glutamyltransferase): Effects of age, sex, body mass index, and pubertal stage.

The present study aims to clarify the effects of sex, age, body mass index (BMI), and puberty on transaminase serum levels in children and adolescents and to provide new age- and sex-related percentiles for alanine aminotransferase (ALT), aspartate aminotransferase (AST), and γ-glutamyltransferase (GGT). Venous blood and anthropometric data were collected from 4,126 cases. Excluded were cases of participants with potential hepatotoxic medication, with evidence of potential illness at the time of blood sampling and non-normal BMI (BMI <10th or >90th). The resulting data (N = 3,131 cases) were used for the calculations of ALT, AST, and GGT percentiles. Age- and sex-related reference intervals were established by using an LMS method of Cole-type method. Serum levels of transaminases follow age-specific patterns and relate to the onset of puberty. This observation is more pronounced in girls than in boys. ALT percentiles showed similar-shaped patterns in both sexes. Multivariate regression confirmed significant effects of puberty and BMI-SDS (ß = 2.21) on ALT. Surprisingly, AST serum levels were negatively influenced by age (ß = -1.42) and BMI-SDS (ß = -0.15). GGT percentiles revealed significant sex-specific differences, correlated positively with age (ß = 0.37) and showed significant association with BMI-SDS (ß = 1.16). CONCLUSION: Current reference values of ALT, AST, and GGT serum levels were calculated for children between 11 months and 16.0 years, using modern analytical and statistical methods. This study extends the current knowledge about transaminases by revealing influences of age, sex, BMI, and puberty on serum concentrations of all three parameters and has for these parameters one of the largest sample sizes published so far. (Hepatology 2017).

Reciprocal Longitudinal Associations Between Adolescents' Media Consumption and Sleep.

Background/Objective: Associations between adolescents' sleep and their media consumption have been shown in several cross-sectional studies. However, longitudinal investigations are still sparse and have mainly investigated associations between sleep duration and the usage of TV or computer games. The present study explored reciprocal longitudinal relationships between the consumption of different screen-based media and sleep-related problems in German adolescents. Participants: Four hundred sixty-seven 10- to 17-year-old adolescents participated in the LIFE Child Study in Leipzig, Germany. Methods: The consumption of screen-based media (TV or video, computer and Internet, mobile phones) as well as sleep-related problems (problems at bedtime, sleep behavior problems, daytime sleepiness) were assessed at two time points, 12 months apart. Reciprocal longitudinal relations were assessed by multiple regression analyses. All associations were controlled for age, gender, socioeconomic status, and dependent variables at baseline. Results: The consumption times of the different screen-based media were significantly related. Similarly, the different sleep-related problems showed significant interrelations. Most importantly, the analyses revealed significant associations between a high baseline consumption of computer and Internet with more problems at bedtime, as well as more daytime sleepiness at follow-up. Furthermore, baseline daytime sleepiness was associated with a higher consumption of TV or video at follow-up. Conclusions: These results indicate a mutual dependency of media consumption and sleep over time.

Relations between sleep duration with overweight and academic stress-just a matter of the socioeconomic status?

OBJECTIVES: Shorter sleep duration in childhood has already been associated with health-related and psychological factors, such as overweight/obesity or stress. This study investigates associations of sleep duration with overweight/obesity and stress related to academic success in school ("academic stress") in dependence on children's socioeconomic status. DESIGN: Cross-sectional. SETTING: LIFE Child Study, a study investigating child development from pregnancy to adulthood. PARTICIPANTS: A total of 1537 (2325 observations) 1- to 14-year-old children were considered. Analyses on academic stress were performed in a subgroup of 450 school-aged children (631 observations). MEASUREMENTS: Associations between sleep duration and overweight/obesity as well as academic stress were analyzed using linear mixed-effect regression models controlling for multiple visits. Importantly, all associations were checked for interactions with families' socioeconomic status. RESULTS: The analyses revealed negative associations between sleep duration and overweight/obesity as well as academic stress, which, however, were only observable in children from families with a low socioeconomic status. The associations were consistent across all ages. CONCLUSIONS: The findings suggest that children from families with a low socioeconomic status have a higher susceptibility for risk factors promoting sleep deficiency, overweight, or academic stress, for example, unhealthy food intake, high media consumption, or the loss of coping strategies for academic stress at school.