PEDIATRICOBESITY doi:10.1111/j.2047-6310.2013.00199.x
Alanine aminotransferase and metabolic syndrome in adolescents: the Korean National Health and Nutrition Examination Survey Study J-H. Park1, S-H. Kim2, S. Park3 and M. J. Park2 1
Songtan Public Health Center, Seongnam-Si, Korea; 2Department of Pediatrics, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea; 3Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA Received 26 October 2012; revised 7 June 2013; accepted 19 August 2013
What is already known about this subject
What this study adds
• Adolescent NAFLD has increased in parallel with obesity. • Elevated serum ALT level is a surrogate marker for NALFD. • Increased ALT levels are closely related to NAFLD and metabolic syndrome.
• Increased ALT within normal range are associated with an increased risk of metabolic syndrome. • All of the five components of metabolic syndrome were associated with high ALT within normal range. • By elevation of ALT, the prevalence of metabolic syndrome increased in obese adolescents and normal-weight adolescents as well.
Summary Background/Aims: The potential interactions between alanine aminotransferase (ALT) and components of metabolic syndrome (MetS) have not been fully investigated in healthy adolescents. This study investigated the impact of a mild ALT elevation on the risks of MetS in healthy Korean adolescents. Methods: From the Korean National Health and Nutrition Examination Surveys 1998–2009, the data of 5026 adolescents aged 10–18 years (2604 boys and 2422 girls) were analysed. Individuals who had ALT levels equal or more than 40 IU L−1 were excluded.
Results: Subjects in the upper ALT tertile had higher mean values of body mass index (BMI), homeostasis model assessment-insulin resistance and prevalence of MetS than subjects in the lower tertile. The risk of each five components of MetS was significantly higher than subjects in the lower tertile. Compared with the subjects in the lower ALT tertile, the prevalence of MetS was higher in the upper tertile among obese adolescents (44.6–50.7% vs. 31.2–40.0%) as well as normal-weight adolescents (5.2–7.7% vs. 2.7–3.2%). Subjects in the upper ALT tertile were at a higher risk of MetS than those in the lower tertile (odds ratio [OR] = 1.95 for boys, OR = 2.00 for girls) after controlling for age and BMI. Conclusions: A high serum ALT within normal range increased the risk of all the components of MetS. The prevalence of MetS increased with the elevation of obesity level, and it increased further with the elevation of ALT tertile. Thus, serum ALT levels in addition to BMI might be useful as a marker for early detection of MetS. Keywords: Adolescents, alanine aminotransferase, metabolic syndrome, obesity.
Address for correspondence: Professor M J Park, Department of Pediatrics, Sanggye Paik Hospital, Inje University College of Medicine, 761-1, Sanggye 7-dong, Nowon-gu, Seoul 139-707, Korea. E-mail: [email protected] © 2013 The Authors Pediatric Obesity © 2013 International Association for the Study of Obesity. Pediatric Obesity 9, 411–418
ORIGINALRESEARCH
ORIGINALRESEARCH
ORIGINALRESEARCH
412 |
J-H. Park et al.
Introduction Non-alcoholic fatty liver disease (NAFLD) in children and adolescents has increased in parallel with the increased prevalence of obesity (1). Although NAFLD can be diagnosed invasively with liver biopsy, several studies demonstrated an association with elevated serum alanine aminotransferase (ALT) levels and the usefulness of ALT as a surrogate marker for NAFLD (2,3). Strong evidence exists for the linkage between elevated serum ALT/NAFLD and metabolic syndrome (MetS). A number of epidemiological and clinical studies of adults have shown that ALT is closely related to the components of MetS in the general population (4,5) and in NAFLD patients as well (6). Many studies of ALT in adults have shown that ALT is closely related to NAFLD (7,8), and MetS (9–11) are increased even in the upper normal range of ALT. Meanwhile, in children and adolescents, the relationship between components of ALT and MetS has not been fully investigated. Although a few studies with small sample sizes demonstrated a positive correlation between components of MetS and elevated ALT levels in obese children (12,13), large-scale studies with nationally representative samples are limited (14–16). The objective of this study was to determine whether a mild elevation of ALT is associated with MetS components and to assess the possible impact of elevated ALT levels on the prevalence of MetS according to the obesity status.
Method Study subjects The data for this study were obtained from the Korean National Health and Nutrition Examination Survey (KNHANES) conducted from 1998 to 2009. This survey is a community-based cross-sectional study that has been conducted by the Division of Chronic Disease Surveillance of Korea Centers for Disease Control and Prevention to assess health and nutrition of a large representative sample of noninstitutionalized civilians in Korea. A stratified, multistage probability sampling design was used for the selection of household units. There were 7071 adolescents aged 10–18 years among those who participated in the survey during the study period. Individuals who had ALT levels equal or greater than 40 IU L−1 or failed to keep fasting for 10 h (n = 1971) were excluded. In addition, those with epilepsy (n = 11) or thyroid dysfunction (n = 0) or HBsAgpositive individuals (n = 63) were excluded. The final
sample for the cross-sectional analyses comprised a total of 5026 individuals (2604 boys and 2422 girls). All participants in this survey provided signed informed consent and all procedures involving human subjects were ethically approved by the Korea Centers for Disease Control and Prevention.
Anthropometric measurements Height and body weight were measured without shoes and clothes using standard equipment and procedures. Waist circumference was taken at the highest point of the iliac crest, with subjects standing in an upright position and recorded at the end of a normal expiration. Blood pressure was measured three times by nurses after a 5-min rest in a sitting position and the average of the second and third measurements was recorded. Body mass index (BMI) was calculated as body weight/body height2 (kg m−2). Obesity was categorized according to the age- and sex-specific BMI percentiles of the national reference charts (17). Overweight was defined as BMI ≥ 85th percentile and
Alanine aminotransferase and metabolic syndrome in adolescents: the Korean National Health and Nutrition Examination Survey Study J-H. Park1, S-H. Kim2, S. Park3 and M. J. Park2 1
Songtan Public Health Center, Seongnam-Si, Korea; 2Department of Pediatrics, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea; 3Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA Received 26 October 2012; revised 7 June 2013; accepted 19 August 2013
What is already known about this subject
What this study adds
• Adolescent NAFLD has increased in parallel with obesity. • Elevated serum ALT level is a surrogate marker for NALFD. • Increased ALT levels are closely related to NAFLD and metabolic syndrome.
• Increased ALT within normal range are associated with an increased risk of metabolic syndrome. • All of the five components of metabolic syndrome were associated with high ALT within normal range. • By elevation of ALT, the prevalence of metabolic syndrome increased in obese adolescents and normal-weight adolescents as well.
Summary Background/Aims: The potential interactions between alanine aminotransferase (ALT) and components of metabolic syndrome (MetS) have not been fully investigated in healthy adolescents. This study investigated the impact of a mild ALT elevation on the risks of MetS in healthy Korean adolescents. Methods: From the Korean National Health and Nutrition Examination Surveys 1998–2009, the data of 5026 adolescents aged 10–18 years (2604 boys and 2422 girls) were analysed. Individuals who had ALT levels equal or more than 40 IU L−1 were excluded.
Results: Subjects in the upper ALT tertile had higher mean values of body mass index (BMI), homeostasis model assessment-insulin resistance and prevalence of MetS than subjects in the lower tertile. The risk of each five components of MetS was significantly higher than subjects in the lower tertile. Compared with the subjects in the lower ALT tertile, the prevalence of MetS was higher in the upper tertile among obese adolescents (44.6–50.7% vs. 31.2–40.0%) as well as normal-weight adolescents (5.2–7.7% vs. 2.7–3.2%). Subjects in the upper ALT tertile were at a higher risk of MetS than those in the lower tertile (odds ratio [OR] = 1.95 for boys, OR = 2.00 for girls) after controlling for age and BMI. Conclusions: A high serum ALT within normal range increased the risk of all the components of MetS. The prevalence of MetS increased with the elevation of obesity level, and it increased further with the elevation of ALT tertile. Thus, serum ALT levels in addition to BMI might be useful as a marker for early detection of MetS. Keywords: Adolescents, alanine aminotransferase, metabolic syndrome, obesity.
Address for correspondence: Professor M J Park, Department of Pediatrics, Sanggye Paik Hospital, Inje University College of Medicine, 761-1, Sanggye 7-dong, Nowon-gu, Seoul 139-707, Korea. E-mail: [email protected] © 2013 The Authors Pediatric Obesity © 2013 International Association for the Study of Obesity. Pediatric Obesity 9, 411–418
ORIGINALRESEARCH
ORIGINALRESEARCH
ORIGINALRESEARCH
412 |
J-H. Park et al.
Introduction Non-alcoholic fatty liver disease (NAFLD) in children and adolescents has increased in parallel with the increased prevalence of obesity (1). Although NAFLD can be diagnosed invasively with liver biopsy, several studies demonstrated an association with elevated serum alanine aminotransferase (ALT) levels and the usefulness of ALT as a surrogate marker for NAFLD (2,3). Strong evidence exists for the linkage between elevated serum ALT/NAFLD and metabolic syndrome (MetS). A number of epidemiological and clinical studies of adults have shown that ALT is closely related to the components of MetS in the general population (4,5) and in NAFLD patients as well (6). Many studies of ALT in adults have shown that ALT is closely related to NAFLD (7,8), and MetS (9–11) are increased even in the upper normal range of ALT. Meanwhile, in children and adolescents, the relationship between components of ALT and MetS has not been fully investigated. Although a few studies with small sample sizes demonstrated a positive correlation between components of MetS and elevated ALT levels in obese children (12,13), large-scale studies with nationally representative samples are limited (14–16). The objective of this study was to determine whether a mild elevation of ALT is associated with MetS components and to assess the possible impact of elevated ALT levels on the prevalence of MetS according to the obesity status.
Method Study subjects The data for this study were obtained from the Korean National Health and Nutrition Examination Survey (KNHANES) conducted from 1998 to 2009. This survey is a community-based cross-sectional study that has been conducted by the Division of Chronic Disease Surveillance of Korea Centers for Disease Control and Prevention to assess health and nutrition of a large representative sample of noninstitutionalized civilians in Korea. A stratified, multistage probability sampling design was used for the selection of household units. There were 7071 adolescents aged 10–18 years among those who participated in the survey during the study period. Individuals who had ALT levels equal or greater than 40 IU L−1 or failed to keep fasting for 10 h (n = 1971) were excluded. In addition, those with epilepsy (n = 11) or thyroid dysfunction (n = 0) or HBsAgpositive individuals (n = 63) were excluded. The final
sample for the cross-sectional analyses comprised a total of 5026 individuals (2604 boys and 2422 girls). All participants in this survey provided signed informed consent and all procedures involving human subjects were ethically approved by the Korea Centers for Disease Control and Prevention.
Anthropometric measurements Height and body weight were measured without shoes and clothes using standard equipment and procedures. Waist circumference was taken at the highest point of the iliac crest, with subjects standing in an upright position and recorded at the end of a normal expiration. Blood pressure was measured three times by nurses after a 5-min rest in a sitting position and the average of the second and third measurements was recorded. Body mass index (BMI) was calculated as body weight/body height2 (kg m−2). Obesity was categorized according to the age- and sex-specific BMI percentiles of the national reference charts (17). Overweight was defined as BMI ≥ 85th percentile and
