Iron stores, liver transaminase levels and metabolic risk in healthy teenagers

Associations between serum ferritin, iron, and liver transaminases in adolescents: a large cross-sectional study

Introduction

Introduction: few previous studies suggest that serum iron status may be associated with liver function, but the relevant evidence remains limited, especially in adolescents. Objective: we aimed to investigate the association between serum ferritin, iron, and liver transaminases in adolescents. Methods: a cross-sectional study including 3,404 adolescents aged 10-19 was performed based on the National Health and Nutrition Examination Survey. Weighted multivariate regression, subgroup analysis, and sensitivity analysis were used. Results: a total of 3,404 adolescents were eventually included. Serum ferritin and iron were positively correlated to alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The association between serum ferritin and ALT remained positive in all genders and races, but only remained positive in girls and several races between serum ferritin and AST. The positive correlations kept present among girls between serum iron and ALT, and also kept present among girls and non-Hispanic whites between serum iron and AST. Additionally, serum ferritin and iron were also positively correlated to elevated ALT and elevated AST using binary logistic regression analysis. After excluding the subjects with serum ferritin levels above the upper limit of normal, the main results remained the same basically. Conclusion: the present results add novel evidences about the associations between serum ferritin, iron, and liver transaminases, which requires more confirmatory studies.

Serum Ferritin Correlates With Liver Fat in Male Adolescents With Obesity

Non-alcoholic fatty liver disease (NAFLD) contributes essentially to the burden of obesity and can start in childhood. NAFLD can progress to cirrhosis and hepatocellular carcinoma. The early phase of NAFLD is crucial because during this time the disease is fully reversible. Pediatric NAFLD shows unique features of histology and pathophysiology compared to adults. Changes in serum iron parameters are common in adult NAFLD and have been termed dysmetabolic iron overload syndrome characterized by increased serum ferritin levels and normal transferrin saturation; however, the associations of serum ferritin, inflammation, and liver fat content have been incompletely investigated in children. As magnetic resonance imaging (MRI) is an excellent measure for the degree of liver steatosis, we applied this method herein to clarify the interaction between ferritin and fatty liver in male adolescents. For this study, one hundred fifty male pediatric patients with obesity and who are overweight were included. We studied a subgroup of male patients with (n = 44) and without (n = 18) NAFLD in whom we determined liver fat content, visceral adipose tissue, and subcutaneous adipose tissue extent with a 1.5T MRI (Philips NL). All patients underwent a standardized oral glucose tolerance test. We measured uric acid, triglycerides, HDL-, LDL-, total cholesterol, liver transaminases, high sensitive CRP (hsCRP), interleukin-6, HbA1c, and insulin. In univariate analysis, ferritin was associated with MRI liver fat, visceral adipose tissue content, hsCRP, AST, ALT, and GGT, while transferrin and soluble transferrin receptor were not associated with ferritin. Multivariate analysis identified hsCRP and liver fat content as independent predictors of serum ferritin in the pediatric male patients. Our data indicate that serum ferritin in male adolescents with obesity is mainly determined by liver fat content and inflammation but not by body iron status.

Ferritin levels throughout childhood and metabolic syndrome in adolescent stage

BACKGROUND AND AIM

Increased ferritin levels have been widely associated with cardiovascular risk in adults. Whether ferritin levels and their changes during childhood are related to metabolic syndrome (MetS) at adolescence is unknown. We aimed to evaluate these associations using levels of ferritin at 5, 10 and 16 years and their linear increases and patterns of sustained increased levels across childhood.

METHODS AND RESULTS

There were four samples evaluated according to non-missing values for study variables at each stage (5 years: 562; 10 years: 381; and 16 years: 567 children; non-missing values at any stage: 379). MetS risk was evaluated as a continuous Z score. Patterns of sustained increased ferritin (highest tertile) and slope of the change of ferritin per year across the follow-up were calculated. Ferritin levels in the highest versus lowest tertile at five and 16 years were significantly positively associated with MetS risk Z score at adolescence in boys and these associations were unaffected by adjustment for covariates. Having high, compared to low/moderate ferritin level at 2 or more time periods between 5 and 16 years was related to higher Mets Z-score in boys only [e.g. 5-10 years adjusted-beta (95 %CI):0.26 (0.05-0.48),P < 0.05]. In girls, ferritin Z score at 10 and 16 years was positively and independently associated with HOMA-IR Z score. In girls, the slope of ferritin per year in the highest tertile was positively associated with MetS risk Z-score [adjusted-beta (95 %CI):0.21 (0.05-0.38),P < 0.05].

CONCLUSIONS

Ferritin levels throughout childhood are positively related to cardiometabolic risk in adolescence, with associations varying by sex.

Studying hepcidin and related pathways in osteoblasts using a mouse model with insulin receptor substrate 1‑loss of function

Hepcidin is one of the most important proteins in iron metabolism. In the present study, its role in iron metabolism and the associated signaling pathways involved was investigated in a mouse model with insulin receptor substrate 1‑loss of function (IRS‑/‑), and osteoblasts in the iron overload condition. Protein expression levels of hepcidin, interleukin 6 (IL‑6), bone morphogenetic protein receptor 1α and ferritin demonstrated a significant increase in the liver of the IRS‑/‑ mice compared with the IRS+/‑ and IRS+/+ mice. Hepcidin levels in the jaw bone were also increased in the IRS‑/‑ mice (although not significantly). Furthermore, mRNA expression levels of bone morphogenetic protein 6 (BMP6) and ferroportin (FPN) were significantly increased in the liver of the IRS‑/‑ mice compared with the other two models, but no significant differences were observed in the transferrin receptor mRNA expression levels. Additionally, the mRNA expression of hepcidin, FPN and IL‑6 was upregulated in osteoblasts after ferric ammonium citrate exposure, while the mRNA expression of BMP6 was inhibited. Collectively, the results of the present study indicated that hepcidin is involved in iron metabolism in IRS‑1‑/‑ mice via the signaling pathways involving BMP6 and IL‑6. Furthermore, hepcidin is also involved in iron metabolism in osteoblasts under iron overload conditions. Therefore, hepcidin and its associated signaling pathway proteins may represent potential targets for the treatment of conditions associated with iron overload.

Serum ferritin levels and polycystic ovary syndrome in obese and nonobese women

OBJECTIVE

The aim of this study is to evaluate serum ferritin levels and polycystic ovary syndrome (PCOS)-related complications in obese and nonobese women.

MATERIALS AND METHODS

This retrospective study included 539 (286 with PCOS and 253 without PCOS).

RESULTS

Serum ferritin correlated with menstrual cycle length, sex hormone-binding globulin, total testosterone, androstenedione, triglyceride, and total cholesterol in both obese and nonobese women. Obese women with high ferritin levels exhibited higher insulin resistance, impaired glucose tolerance, and liver enzymes (glutamic oxaloacetic transaminase, glutamic pyruvic transaminase) than obese women with low ferritin levels. However, among nonobese women, insulin resistance and risk of diabetes were not significantly different between the high and low ferritin groups. Independent of obesity, hypertriglyceridemia was the major metabolic disturbance observed in women with elevated serum ferritin levels.

CONCLUSION

Elevated serum ferritin levels are associated with increased insulin resistance and risk of diabetes in obese women but not in nonobese women. However, higher serum ferritin levels were correlated with a greater risk of hyperglyceridemia in both obese and nonobese women. Therefore, hypertriglyceridemia in women with PCOS might be associated with iron metabolism.

Mitochondrial Haplogroup T Is Associated with Obesity in Austrian Juveniles and Adults

Background

Recent publications have reported contradictory data regarding mitochondrial DNA (mtDNA) variation and its association with body mass index. The aim of the present study was to compare the frequencies of mtDNA haplogroups as well as control region (CR) polymorphisms of obese juveniles (n = 248) and obese adults (n = 1003) versus normal weight controls (n_juvenile = 266, n_adults = 595) in a well-defined, ethnically homogenous, age-matched comparative cohort of Austrian Caucasians.

Methodology and Principal Findings

Using SNP analysis and DNA sequencing, we identified the nine major European mitochondrial haplogroups and CR polymorphisms. Of these, only the T haplogroup frequency was increased in the juvenile obese cohort versus the control subjects [11.7% in obese vs. 6.4% in controls], although statistical significance was lost after adjustment for sex and age. Similar data were observed in a local adult cohort, in which haplogroup T was found at a significantly higher frequency in the overweight and obese subjects than in the normal weight group [9.7% vs. 6.2%, p = 0.012, adjusted for sex and age]. When all obese subjects were considered together, the difference in the frequency of haplogroup T was even more clearly seen [10.1% vs. 6.3%, p = 0.002, OR (95% CI) 1.71 (1.2–2.4), adjusted for sex and age]. The frequencies of the T haplogroup-linked CR polymorphisms C16294T and the C16296T were found to be elevated in both the juvenile and the adult obese cohort compared to the controls. Nevertheless, no mtDNA haplogroup or CR polymorphism was robustly associated with any of several investigated metabolic and cardiovascular parameters (e.g., blood pressure, blood glucose concentration, triglycerides, cholesterol) in all obese subjects.

Conclusions and Significance

By investigation of this large ethnically and geographically homogenous cohort of Middle European Caucasians, only mtDNA haplogroup T was identified as an obesity risk factor.

The Potential Role of Iron and Copper in Pediatric Obesity and Nonalcoholic Fatty Liver Disease

Obesity is a rapidly growing health problem and is paralleled by a multitude of comorbidities, including nonalcoholic fatty liver disease (NAFLD). NAFLD has become the most common chronic liver disease in both adults and children. The current understanding of NAFLD is still fragmentary. While simple steatosis is characterized by the interplay between excessive free fatty acid accumulation and hepatic insulin resistance, the progression to NASH has been related to oxidative stress and a proinflammatory state with dysbalanced adipokine, cytokine levels, and endotoxin-mediated immune response. In addition, oxidative stress has been suggested to play a central role for the sequelae leading to NASH. Trace elements are critical in regulatory, immunologic, and antioxidant functions resulting in protection against inflammation and peroxidation and consequently against the known comorbidities of obesity. Disruptions of the metal detoxification processes located in the liver are plausibly related to NAFLD development via oxidative stress. Perturbations of iron and copper (Cu) homeostasis have been shown to contribute to the pathogenesis of NAFLD. This review presents current data from pediatric studies. In addition, data from adult studies are summarized where clinical relevance may be extrapolated to pediatric obesity and NAFLD.

Association between serum alanine aminotransferase level and obesity indices in Korean adolescents

Purpose

To analyze the correlation between serum alanine aminotransferase (ALT) and obesity indices including body mass index (BMI), body fat percentage (BFP), total fat mass (FM), truncal fat mass (TFM), waist circumference (WC), and waist-to-height ratio (WHtR) in Korean adolescents.

Methods

This was a cross-sectional study based on data derived from the 2010-2011 Korean National Health and Nutrition Examination Surveys (KNHANES). Subjects were Korean adolescents aged 10-18 years (871 total; 475 boys and 396 girls) who participated in KNHANES.

Results

In both sexes, BMI, FM, TFM, WC, and WHtR were higher when ALT levels were in the 4th quartile. In boys, there was a significant positive correlation between ALT level and BMI, BFP, FM, TFM, WC, and WHtR (r=0.55, P<0.0001 for BMI; r=0.52, P<0.0001 for BFP; r=0.58, P<0.0001 for FM; r=0.61, P<0.0001 for TFM; and r=0.56, P<0.0001 for WC; r=0.62, P<0.0001 for WHtR), and the correlation coefficient was higher than that in girls.

Conclusion

Our results suggest a significant positive association between serum ALT level and obesity indices in male adolescents.

Dysregulation of iron and copper homeostasis in nonalcoholic fatty liver

Elevated iron stores as indicated by hyperferritinemia with normal or mildly elevated transferrin saturation and mostly mild hepatic iron deposition are a characteristic finding in subjects with non-alcoholic fatty liver disease (NAFLD). Excess iron is observed in approximately one third of NAFLD patients and is commonly referred to as the “dysmetabolic iron overload syndrome”. Clinical evidence suggests that elevated body iron stores aggravate the clinical course of NAFLD with regard to liver-related and extrahepatic disease complications which relates to the fact that excess iron catalyses the formation of toxic hydroxyl-radicals subsequently resulting in cellular damage. Iron removal improves insulin sensitivity, delays the onset of type 2 diabetes mellitus, improves pathologic liver function tests and likewise ameliorates NAFLD histology. Several mechanisms contribute to pathologic iron accumulation in NAFLD. These include impaired iron export from hepatocytes and mesenchymal Kupffer cells as a consequence of imbalances in the concentrations of iron regulatory factors, such as hepcidin, cytokines, copper or other dietary factors. This review summarizes the knowledge about iron homeostasis in NAFLD and the rationale for its therapeutic implications.

Liver enzymes, metabolomics and genome-wide association studies: From systems biology to the personalized medicine

For several decades, serum levels of alanine (ALT) and aspartate (AST) aminotransferases have been regarded as markers of liver injury, including a wide range of etiologies from viral hepatitis to fatty liver. The increasing worldwide prevalence of metabolic syndrome and cardiovascular disease revealed that transaminases are strong predictors of type 2 diabetes, coronary heart disease, atherothrombotic risk profile, and overall risk of metabolic disease. Therefore, it is plausible to suggest that aminotransferases are surrogate biomarkers of “liver metabolic functioning” beyond the classical concept of liver cellular damage, as their enzymatic activity might actually reflect key aspects of the physiology and pathophysiology of the liver function. In this study, we summarize the background information and recent findings on the biological role of ALT and AST, and review the knowledge gained from the application of genome-wide approaches and “omics” technologies that uncovered new concepts on the role of aminotransferases in human diseases and systemic regulation of metabolic functions. Prediction of biomolecular interactions between the candidate genes recently discovered to be associated with plasma concentrations of liver enzymes showed interesting interconnectivity nodes, which suggest that regulation of aminotransferase activity is a complex and highly regulated trait. Finally, links between aminotransferase genes and metabolites are explored to understand the genetic contributions to the metabolic diversity.

Alanine aminotransferase and metabolic syndrome in adolescents: the Korean National Health and Nutrition Examination Survey Study

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

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.

WHAT THIS STUDY ADDS

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.

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.

Obesity as an emerging risk factor for iron deficiency

Iron homeostasis is affected by obesity and obesity-related insulin resistance in a many-facetted fashion. On one hand, iron deficiency and anemia are frequent findings in subjects with progressed stages of obesity. This phenomenon has been well studied in obese adolescents, women and subjects undergoing bariatric surgery. On the other hand, hyperferritinemia with normal or mildly elevated transferrin saturation is observed in approximately one-third of patients with metabolic syndrome (MetS) or nonalcoholic fatty liver disease (NAFLD). This constellation has been named the “dysmetabolic iron overload syndrome (DIOS)”. Both elevated body iron stores and iron deficiency are detrimental to health and to the course of obesity-related conditions. Iron deficiency and anemia may impair mitochondrial and cellular energy homeostasis and further increase inactivity and fatigue of obese subjects. Obesity-associated inflammation is tightly linked to iron deficiency and involves impaired duodenal iron absorption associated with low expression of duodenal ferroportin (FPN) along with elevated hepcidin concentrations. This review summarizes the current understanding of the dysregulation of iron homeostasis in obesity.

Relationship between Serum Levels of Body Iron Parameters and Insulin Resistance and Metabolic Syndrome in Korean Children

OBJECTIVES

An increase in serum ferritin and levels of the cleaved soluble form of transferrin receptor (sTfR) are related to several metabolic conditions. We evaluated the relationship between body iron status indicators, including ferritin and sTfR, and insulin resistance and metabolic syndrome (MetS) in Korean children.

METHODS

A cross-sectional study was conducted on 1350 children in Korea. Anthropometrical parameters; lipid profiles; levels of glucose, insulin, and leptin; and iron status indicators, including sTfR, serum ferritin, serum iron, total iron-binding capacity (TIBC), and transferrin saturation (TS), were analyzed.

RESULTS

Although serum sTfR levels were significantly higher in boys than in girls (2.20 vs. 2.06 mg/L, p < 0.0001), serum iron and TS were higher in girls than in boys (101.38 vs. 95.77 mg/L, p = 0.027 and 30.15 vs. 28.91%, p = 0.04, respectively). Waist circumference (WC) and leptin were most significantly associated with body iron indicators when adjusted for age and sex. After adjusting for age, sex, and WC, sTfR levels showed the strongest positive association with leptin levels (p = 0.0001). Children in the highest tertile for homeostasis model assessment-insulin resistance (HOMA-IR) had higher TIBC (p = 0.0005) and lower serum iron (p = 0.0341), and the lowest TS (p < 0.0001) after adjustment for confounders. Children with higher sTfR were most significantly associated with risk of MetS compared with those lower sTfR (p = 0.0077).

CONCLUSION

The associations of serum levels of iron metabolism markers with leptin levels, HOMA-IR, and MetS suggest that iron-related factors may involve insulin resistance and MetS.

Low serum long-acting natriuretic peptide level correlates with metabolic syndrome in hypertensive patients: a cross-sectional study

BACKGROUND AND AIMS

Long-acting natriuretic peptide (LANP) is one of the peptide hormones in atrial natriuretic peptide (ANP) prohormone. Its biological properties are blood pressure regulation, maintenance of plasma volume and anticancer effects. The aim of this study was to evaluate the relationship between metabolic syndrome (MetS) and fasting serum LANP concentration in hypertensive patients.

METHODS

Fasting blood samples were obtained from 224 patients with or without hypertension. MetS and its components were defined using diagnostic criteria from the International Diabetes Federation.

RESULTS

Eighty-eight hypertensive patients (59.5 %) had MetS. Hypertensive patients with MetS had higher body weight (p = 0.003), waist circumference (p = 0.003), body mass index (p = 0.002), triglyceride concentrations (p = 0.029), insulin levels (p = 0.001), HOMA-IR (p <0.003) and HOMA-β (p = 0.049) and lower HDL-C concentrations (p = 0.001), LANP levels (p = 0.012) than those without MetS. The univariable linear regression analysis showed that age (p = 0.038) and the BUN concentration (p = 0.022) were positively correlated with the serum LANP levels, whereas the insulin level (p = 0.001), HOMA-IR (p = 0.004), and HOMA-β (p = 0.001) were negatively correlated with the fasting serum LANP levels among the hypertensive patients. Multivariable forward stepwise linear regression analysis of the significant variables showed that the HOMA-β (β = -0.387, R(2) = 0.141, p <0.001) was an independent predictor of fasting serum LANP levels in hypertensive patients.

CONCLUSIONS

LANP level is significantly reduced in hypertensive patients affected by MetS and is negatively related to pancreatic beta cell function in hypertensive patients.

Iron homeostasis in the metabolic syndrome

The metabolic syndrome (MetS) affects iron homeostasis in a many-faceted fashion. On the one side, hyperferritinaemia with normal or mildly elevated transferrin saturation is observed in approximately one-third of patients with non-alcoholic fatty liver disease (NAFLD) or the MetS. This constellation has been named the 'dysmetabolic iron overload syndrome (DIOS)'. Current evidence suggests that elevated body iron stores exert a detrimental effect on the clinical course of obesity-related conditions and that iron removal improves insulin sensitivity and delays the onset of T2DM. On the other side, iron deficiency is a frequent finding in more progressed stages of obesity. The mechanisms underlying the DIOS and obesity-related iron deficiency appear strikingly similar as elevated hepcidin concentrations, low expression of duodenal ferroportin (FPN) and impaired iron absorption are found in both conditions. This review summarizes the current knowledge about the dysregulation of iron homeostasis in the MetS and particularly in its hepatic manifestation NAFLD.

Hydroxyl radical-modified fibrinogen as a marker of thrombosis: the role of iron

Excessive free iron in blood and in organ tissues (so called iron overload) has been observed in degenerative diseases such as atherosclerosis, cancer, neurological, and certain autoimmune diseases, in which fibrin-like deposits are also found. Although most of the body iron is bound to hemoglobin and myoglobin in a divalent ferrous form, a certain amount of iron exists in blood as a trivalent (ferric) ion. This particular chemical state of iron has been shown to be toxic to the human body when not controlled by endogenous and/or dietary chelating agents. Experiments described in this paper show for the first time that ferric ions (Fe(3+)) can generate hydroxyl radicals without participation of any redox agent, thus making it a special case of the Fenton reaction. Ferric chloride was also demonstrated to induce aggregation of purified fibrinogen at the same molar concentrations that were used for the generation of hydroxyl radicals. Iron-aggregated fibrinogen, by contrast to native molecule, could not be dissociated into polypeptide subunit chains as shown in a polyacrylamide gel electrophoresis. The mechanism of this phenomenon is very likely based on hydroxyl radical-induced modification of fibrinogen tertiary structure with the formation of insoluble aggregates resistant to enzymatic and chemical degradations. Soluble modified fibrinogen species can be determined in blood of thrombotic patients by the reaction with protamine sulfate and/or by scanning electron microscopy. In view of these findings, it is postulated that iron-induced alterations in fibrinogen structure is involved in pathogenesis of certain degenerative diseases associated with iron overload and persistent thrombosis. It is concluded that the detection of hydroxyl radical-modified fibrinogen may be utilized as a marker of a thrombotic condition in human subjects.

Hyperferritinemia and hyperuricemia may be associated with liver function abnormality in obese adolescents

BACKGROUND

The iron status in human body and its association with liver function in adolescents was rarely studied. The objective was to investigate the association among the levels of serum ferritin, uric acid and alanine aminotransferase (ALT) in adolescents.

METHODS AND RESULTS

A total of 2090 adolescents negative for hepatitis B surface antigen from one junior high school (786, 12-13 years), three senior high schools (973, 15-16 years) and one college (331, 18-19 years) participated in this survey. Anthropometric and biochemical measurements, including complete blood count, ALT, serum ferritin and uric acid were performed. An ALT>42 U/L was defined as elevated, a ferritin level >200 µg/L was defined as hyperferritinemia. A uric acid level >460 µmol/L in males and >340 µmol/L in females was defined as hyperuricemia. The chi-squared test, linear regression and multivariate logistic regression were used for the data analysis. Elevated ALT levels were detected in 76 (3.6%) students and were more prevalent in males than females (6.4% vs. 2.0%, p<0.001). The univariate analysis found gender, age group, body mass index, ferritin level, uric acid level and white blood cell count all to be significantly associated with elevated ALT. Linear regression showed a positive correlation among log(ferritin), uric acid level and ALT level. Elevated ALT occurred more frequently at ferritin level >100 µg/L. The logistic regression analysis found that body mass index, hyperferritinemia and hyperuricemia were significant factors associated with the ALT elevation, but gender, age, and white blood cell count were not.

CONCLUSIONS

Hyperferritinemia and hyperuricemia are two independently significant factors associated with ALT elevation among obese adolescents. More studies are needed to corroborate any hypothesis related to these phenomena.

Iron load and liver enzymes in 10- and 13-year-olds

OBJECTIVES

Iron plays a pivotal role in adult steatosis, but its role in child and adolescent steatosis is unclear. We investigated the effect of dietary iron, serum iron, and ferritin on serum transaminases and γ-glutamyltransferase in 10- and 13-year-olds.

PATIENTS AND METHODS

The study included 4894 fifth and eighth graders enrolled between 2006 and 2009 in all schools in Shunan City, Japan. Multiple regression analyses were performed with adjustments for grade, sex, z score of the body mass index, serum lipids, plasma glucose, frequency of sports activities, having a single parent, number of siblings, tobacco smoking behavior, passive smoking at home, resident areas, and schools, using linear mixed models. In addition, we analyzed ferritin and insulin resistance in randomly selected subset of participants.

RESULTS

Dietary iron intake was positively associated with serum alanine aminotransferase levels (standardized coefficient β = 2.35, P = 0.019). Serum iron concentrations were associated with transaminase and γ-glutamyltransferase levels (β = 3.22, and 4.05, respectively, P < 0.01). In the subset of 421 subjects with further serum analysis, serum ferritin levels were significantly associated with serum enzyme levels (β = 2.43-3.35; P < 0.05) and showed significant odds ratio for the elevated alanine aminotransferase levels (1.05 for 1 SD with 95% confidence intervals 1.02-1.08). However, iron load did not show a positive association with insulin resistance.

CONCLUSIONS

Although an effect size for iron is small in regression analyses, iron is implicated in increased transaminase levels in prepubertal and pubertal children.