Relationships among serum iron, inflammation, and body mass index in children

High prevalence of malnutrition and vitamin A deficiency among schoolchildren of rural areas in Malaysia using a multi-school assessment approach

Childhood malnutrition is known as a public health concern globally. The present study aims to assess the anthropometry and blood biochemical status of rural primary schoolchildren in Malaysia. A total of 776 children (7-11 years old) from ten rural primary schools from five states were included in this study. Nutritional outcomes were assessed based on sex, age group and school categories among the children (median age: 9 years (P25:8, P75:10)). The overall prevalence of malnutrition was 53·4 %. Vitamin A deficiency (VAD) was recorded at 20·6 and 39·8 % based on retinol and retinol-binding protein (RBP) levels, respectively. Anaemia, iron deficiency (ID), iron-deficiency anaemia (IDA) and elevated inflammation were found at 14·9, 17·9, 9·1 and 11·5 %, respectively. Malnutrition, VAD, anaemia, ID, IDA and elevated inflammation were more prevalent among Orang Asli (OA) schoolchildren compared with Non-Orang Asli schoolchildren. Higher occurrences of VAD and anaemia were also found among children aged <10 years. Retinol, RBP, α-carotene, ferritin and haemoglobin levels were lower among undernourished children. Besides, overweight/obese children exhibited a higher level of high-sensitivity C-reactive protein. Multivariate analysis demonstrated that OA school children (adjusted OR (AOR): 6·1; 95 % CI 4·1, 9·0) and IDA (AOR: 3·6; 95 % CI 1·9, 6·6) were associated with stunting among this population. The present study revealed that malnutrition, micronutrient deficiencies and anaemia are prevalent among rural primary schoolchildren in Malaysia, especially those from OA schools and younger age children (<10 years). Hence, more appropriate and targeted measures are needed to improve the nutritional status of these children.

Changes in obesity and iron deficiency between 4 and 9 years of age. Longitudinal study of childhood obesity (ELOIN)

BACKGROUND

Recent studies revealed that children who are overweight have a higher risk of iron deficiency, although the etiology of this relationship remains unclear. The aim of the study was to evaluate the association between changes in obesity status between 4 and 9 years of age and iron deficiency.

SUBJECTS

This population-based cohort study included 1347 children from the ELOIN study, conducted in Madrid, Spain. Follow-up with physical examinations and a computer-assisted telephone interview were carried out at 4, 6 and 9 years of age, and a blood test was performed at 9 years.

METHODS

Changes in obesity were estimated based on body mass index and waist circumference, according to the persistence or variation in obesity rates at 4, 6 and 9 years and were classified as follows: (1) Stable without obesity; (2) Remitting obesity at 9 years; (3) Incident obesity or relapse at 9 years; and (4) Stable with obesity. Iron deficiency was defined as transferrin saturation value below 16%. Odds ratios (ORs) for iron deficiency were estimated according to obesity status using logistic regression and adjusted for confounding variables, including C-reactive protein (CRP).

RESULTS

The prevalence of iron deficiency in the stable general obesity (GO) and abdominal obesity (AO) groups was 38.2% and 41.2%, versus 23.6% and 23.4% in the stable without obesity groups, respectively. The ORs for iron deficiency were 1.85 (95% CI: 1.03-3.32) in the stable GO group and 2.34 (95% CI: 1.29-4.24) in the stable AO group. This association disappeared when CRP was included in the analysis.

CONCLUSIONS

An extended state of obesity during the first stages of life is associated with iron deficiency, and this association may be mediated by CRP. Prevention and early detection of obesity in children should be a priority to avoid a double burden of malnutrition.

The Association between Hepcidin and Iron Status in Children and Adolescents with Obesity

Introduction

Iron deficiency (ID) is the most common nutritional deficiency found in pediatric practice. A higher prevalence of ID may be found in children with obesity. Obesity is a chronic low-grade inflammatory condition. It is postulated that inflammation increases hepcidin, a regulator of iron homeostasis. The aim of this study was to investigate the associations between iron status, hepcidin, and BMI-standard deviation score (BMI-SDS) in children with and without obesity.

Methods

A cross-sectional study of Thai children with obesity (5 to 15 years old) versus age- and sex-matched, nonobese controls was conducted. A total of 63 children with obesity and 27 controls were enrolled. Complete blood count, serum iron, ferritin, transferrin saturation, and total iron binding capacity were analyzed. Serum hepcidin-25 was assayed using a hepcidin ELISA Kit (Human Hepc25).

Results

There were 63 children with obesity, the median age (IQR) being 10 (9–13) years, and 27 controls. The median (IQR) BMI-SDS of the obese group was 2.3 (2.0–2.6) vs. −0.5 ((−1.3)−0.4) of the control group. ID was diagnosed in 27 children in the obese group (42.9%); 4 of the children with obesity and ID had anemia. Serum hepcidin-25 levels of the children with ID vs. without ID in the obese group were not significantly different (median (IQR) 25 (12.9–49.2) and 26.4 (12.6–43.6), respectively) but both of them were significantly higher than controls (19.7 (8.3–25.5) ng/ml, p = 0.04). BMI-SDS was positively correlated with hepcidin-25 (r = 0.28, p = 0.001).

Conclusion

Prevalence of iron deficiency in Thai children with obesity and serum hepcidin-25 was higher than controls. Further study in a larger population, preferably with interventions such as weight loss program, is warranted to clarify this association.

Anthropometric Markers and Iron Status of 6-12-Year-Old Thai Children: Associations and Predictors

Introduction

Obesity may be associated with poor iron status. The objective of this study was to investigate the association between different indices of iron status and anthropometric measurements in Thai children.

Materials and Methods

Anthropometry (weight, height, waist circumference (WC), and body composition assessed by bioelectrical impedance analysis) and iron indices were measured in 336 Thai children aged 6-12 years. Iron deficiency (ID) was defined using two or more of the following: (1) %transferrin saturation (%Tsat) < 16%; (2) serum ferritin (SF) < 15 μg/mL; and (3) soluble transferrin receptor (sTfR) > 5 mg/L. Iron deficiency anaemia (IDA) was defined as haemoglobin < WHO age cutoff combined with ID. Overweight and obesity were defined as body mass index (BMI) standard deviation score (SDS) ≥ +1 SDS or +2 SDS, respectively (WHO growth reference).

Results

BMI SDS was significantly positively correlated with sTfR and SF (sTfR, r: 0.209, p < 0.001; SF, r: 0.214, p < 0.001) and negatively correlated with %Tsat (r: -0.132, p = 0.013). Correlations between WC SDS and %fat mass and each iron marker were similar. The percentage with low SF was significantly lower than that using other individual markers. ID prevalence was not significantly different between normal-weight and overweight/obesity groups although a significantly higher proportion of overweight/obese children had sTfR >5 mg/L. Puberty and menarche were significant predictors of ID (puberty adjusted OR: 2.20, 95% CI: 0.43, 11.25; menarche adjusted OR: 6.11, 95% CI: 1.21, 30.94).

Conclusion

Greater adiposity was associated with poorer iron status. However, SF may not be a good indicator of iron status in Thai children, particularly in those who are overweight/obese, whereas sTfR merits further investigation.

Carnosine supplementation reduces plasma soluble transferrin receptor in healthy overweight or obese individuals: a pilot randomised trial

Abnormalities of iron homeostasis have been linked to insulin resistance, type 2 diabetes and cardiovascular disease. Carnosine, an over-the-counter food supplement with chelating properties, has been shown to decrease serum iron and improve glucose metabolism in diabetic rodents. We have previously demonstrated that carnosine supplementation prevented worsening of glucose metabolism in healthy overweight and obese middle-aged adults. Yet, the impact of carnosine on markers of iron metabolism in humans has not been investigated. We aimed to determine whether carnosine supplementation has an effect on iron parameters in overweight and obese, otherwise healthy adults. We included 26 participants, who were randomly allocated to receive 1 g carnosine (n = 14) or identical placebo (n = 12) twice daily for 12 weeks. Iron parameters including iron, ferritin, transferrin, soluble transferrin receptor, total iron binding capacity and iron saturation were measured in serum or plasma by standard commercial assays. Carnosine supplementation decreased plasma soluble transferrin receptor compared to placebo (mean change difference ± standard error: - 0.07 ± 0.03 mg/l, p = 0.04). None of the other iron parameters were different between carnosine and placebo groups. At follow-up, soluble transferrin receptor was associated inversely with urinary carnosine concentrations and positively with serum carnosinase-1 activity (both p < 0.02). Our findings suggest that carnosine may modulate iron metabolism in high-risk groups which could ameliorate insulin resistance and prevent type 2 diabetes. Larger human clinical trials are required to confirm our results.

A review of iron studies in overweight and obese children and adolescents: a double burden in the young?

INTRODUCTION

The connection between iron and excessive adiposity has received much research interest. Although children and adolescents have unique developmental phases and nutritional demands, to date, reviews of iron in the overweight (OW) and obese (OB) have combined studies of children and adults or have focussed on adults.

PURPOSE

The aim of this review was to critically evaluate studies of the relationship between iron and OW and obesity in children and adolescents, with emphasis on iron status, oral iron response, dietary intake and systemic inflammatory markers.

METHODS

A PubMed search was conducted to identify relevant articles published up to December 2015. Combinations of the following keywords were used: iron, OW, OB, children, adolescents, diet, hepcidin, inflammation, fortification, supplementation, weight loss, trace elements, obesity, iron deficiency (ID), minerals.

RESULTS AND CONCLUSION

A higher prevalence of ID, or risk of ID, among OW and OB children and adolescents has been consistently observed. Chronic inflammation caused by excessive adiposity offers a plausible explanation for this finding, rather than dietary factors. However, future studies must employ screening for the presence of both acute and chronic infections and inflammatory conditions and report other factors such as pubertal status. Intervention studies, although few, indicate that OW and OB children and adolescents have reduced response to oral iron. Further trials are needed to explore the connection between body fat mass, inflammatory proteins and iron absorption, together with the effect of weight loss on iron status in iron-deficient OW and OB children and adolescents.

Iron homeostasis and serum hepcidin-25 levels in obese children and adolescents: relation to body mass index

BACKGROUND/AIMS

The etiology of the hypoferremia of obesity is unclear. Hepcidin is the body's main regulator of systemic iron (Fe) and has been reported to be elevated in obese patients. Thus, we aimed to assess Fe status and serum hepcidin-25 levels and their relationship with body mass index (BMI) in obese Egyptian children and adolescents.

METHODS

Fifty obese children were compared to 50 age-, sex- and pubertal stage- matched controls. All subjects were subjected to history and anthropometric assessment and measurement of serum Fe, total iron binding capacity (TIBC), ferritin, transferrin saturation (TS), soluble transferrin receptor (sTfR) and hepcidin.

RESULTS

Fe, TS and TIBC were lower, while ferritin, sTfR and hepcidin-25 were higher in obese patients than controls. BMI standard deviation score (SDS) correlated negatively with Fe (r = -0.82, p < 0.01), TS (r = -0.79, p = 0.02) and TIBC (r = -0.69, p = 0.02), and positively with ferritin (r = +0.73, p < 0.001), sTfR (r = +0.80, p < 0.01) and hepcidin (r = +0.95, p < 0.001). Higher BMI SDS and hepcidin were risk factors for iron deficiency (ID).

CONCLUSIONS

Hypoferremia and elevated hepcidin-25 are prevalent in obese children and correlated with BMI SDS. The connection between hepcidin and inflammation could explain the association of ID with obesity.

Association of body mass index with hemoglobin concentration and iron parameters in Iranian population

Background. Studies have reported that obesity has an adverse effect on iron metabolism. Obesity is characterized by chronic, low-grade, systemic inflammation and anemia of chronic disease with elevated serum ferritin and decreased level of serum iron, transferrin saturation, and hemoglobin. Therefore, we examined the association of body mass index with hemoglobin concentration and iron parameters in this study. Methods. This cross-sectional study was conducted in Yazd to assess the relation of body mass index with hemoglobin and iron parameters among 406 adult patients 18–65 years old. Diabetes and conditions that could influence body iron stores were excluded. Results. There is no difference in hemoglobin concentrations, MCV, serum iron, TIBC, transferrin saturation index, and ferritin between normal weight, overweight, and obese persons. Conclusion. Nutritional status of persons and intake of high iron foods by obese persons should be considered. Also, other inflammatory markers should be evaluated in the future studies.

Association between common iron store markers and hemoglobin in children with chronic kidney disease

BACKGROUND

Serum ferritin and transferrin saturation (TSAT) are used to assess iron status in children with chronic kidney disease (CKD), but their sensitivity in identifying those at risk of lower hemoglobin (HGB) values is unclear.

METHODS

We assessed the association of iron status markers (ferritin, TSAT, and serum iron) with age- and gender-related HGB percentile in mild-to-moderate CKD in 304 children in the Chronic Kidney Disease in Children (CKiD) Study. Standardized HGB percentile values were examined by KDOQI-recommended ferritin (≥ 100 ng/ml) and TSAT (≥ 20 %) thresholds. Regression tree methods were used to identify iron status markers and clinical characteristics most associated with lower HGB percentiles.

RESULTS

The cohort was 62 % male, 23 % African American, and 12 % Hispanic, median age 12 years, and median HGB 12.9 g/dl. 34 % had low TSAT and 93 % low ferritin as defined by KDOQI. Distribution of HGB percentile values was lower in those with ferritin ≥ 100 ng/ml, while TSAT ≥ 20 % was associated with only modest increase in HGB percentile. In regression tree analysis, lower glomerular filtration rate (GFR), serum iron <50 μg/dl and ferritin ≥ 100 ng/ml were most strongly associated with lower HGB percentile.

CONCLUSIONS

The level of GFR was significantly associated with HGB. Higher serum ferritin was associated with lower HGB in this cohort. Low serum iron in the context of normal/increased ferritin and low HGB may be a useful indicator of iron-restricted erythropoiesis.

Anemia in children with chronic kidney disease

Anemia is a common comorbidity in children with chronic kidney disease (CKD). This condition is associated with multiple adverse clinical consequences and its management is a core component of nephrology care. Increased morbidity and mortality, increased risk of cardiovascular disease and decreased quality of life have been associated with anemia of CKD in children. Although numerous complex factors interact in the development of this anemia, erythropoietin deficiency and iron dysregulation (including iron deficiency and iron-restricted erythropoiesis) are the primary causes. In addition to iron supplementation, erythropoietin-stimulating agents (ESAs) can effectively treat this anemia, but there are important differences in ESA dose requirements between children and adults. Also, hyporesponsiveness to ESA therapy is a common problem in children with CKD. Although escalating ESA doses to target increased hemoglobin values in adults has been associated with adverse outcomes, no studies have demonstrated this association in children. The question of appropriate target hemoglobin levels in children, and the approach by which to achieve these levels, remains under debate. Randomized, controlled studies are needed to evaluate whether normalization of hemoglobin concentrations is beneficial to children, and whether this practice is associated with increased risks.

Hemoglobin differences by race in children with CKD

BACKGROUND

There are known racial disparities in the prevalence of anemia in adults with chronic kidney disease (CKD), but these differences have not been well described in children.

STUDY DESIGN

Cohort study, cross-sectional analysis.

SETTING & PARTICIPANTS

The Chronic Kidney Disease in Children (CKiD) Study is a multicenter prospective cohort study of children with mild to moderate CKD. This analysis included 429 children of African American or white race.

PREDICTOR

Race.

OUTCOMES & MEASUREMENTS

This study examined the association of race with hemoglobin level. Both multiple linear regression and generalized gamma modeling techniques were used to characterize the association between race and hemoglobin level.

RESULTS

79% of the cohort was white, 21% was African American. Neither median hemoglobin level nor frequency of erythropoiesis-stimulating agent use differed by race. In multivariate analysis, lower levels of iohexol-measured glomerular filtration rate, African American race, and glomerular disease (vs nonglomerular disease) as the underlying cause of CKD were independently associated with decreased hemoglobin levels; independent of glomerular filtration rate and CKD diagnosis, African American children had average hemoglobin levels that were 0.6 g/dL (95% CI, -0.9 to -0.2 g/dL) lower than those of white children. Generalized gamma modeling showed that differences in hemoglobin levels observed by race become more pronounced when moving from high to low in the overall hemoglobin level distribution.

LIMITATIONS

Cross-sectional analysis cannot establish causality, and data for iron stores were not available for all patients.

CONCLUSIONS

African American compared with white children have lower hemoglobin values in CKD independent of the underlying cause of CKD. These racial differences in hemoglobin levels appear to increase at the lower end of the hemoglobin level distribution in this population.