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Sex differences in iron stores of adolescents: what is normal?
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Paediatrics.
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Paediatrics.
1995 (English)In: Journal of Pediatric Gastroenterology and Nutrition - JPGN, ISSN 0277-2116, E-ISSN 1536-4801, Vol. 20, no 2, 215-24 p.Article in journal (Refereed) Published
Abstract [en]

We evaluated iron status and its determinants in healthy adolescents. Fasting morning blood samples from a school-based cross-sectional study were analyzed for serum ferritin (SF), serum iron, total iron-binding capacity, and circulating transferrin receptors. Physical development, chronic disease, medication, dietary intake, and physical activity were assessed using clinical examination, questionnaires, and 7-day records. The risk of having low serum ferritin values was estimated using bivariate and multivariate regression. Subjects were 867 healthy Swedish adolescents, 14- and 17-year-olds (472 boys and 395 girls). SF values increased with pubertal stage in boys but not in girls. Five percent of the boys and 15% of the girls had SF values < 12 micrograms/L. Of the 17-year-old boys, 7% compared to 1% of the 17-year-old girls had SF values > 100 micrograms/L. Forty-one percent of cases with SF values > 12 micrograms/L had serum iron values < 15 microM, and 22% had transferrin saturation values < 16%. Mean total iron intakes of the boys were high [1.6 times recommended daily allowance (RDA)] and mean intakes of the girls were adequate (0.9 times RDA). Low heme iron intakes increased the risk of low iron stores (< 12 micrograms/L) in girls but not in boys. Total iron intake or other dietary factors, physical development, or level of physical activity did not influence the risk of low SF. The findings of this study suggest that the differences in iron status between boys and girls in adolescence results primarily from biological differences other than menstrual bleeding or insufficient iron intake. Furthermore, the results question the role of SF as an indicator of iron deficiency in adolescence, in particular if age and sex are not taken into consideration. We suggest that different reference values for SF, including the cut-off limit for low SF, adjusted for age and sex, should be considered. The high iron intakes and corresponding high SF values found in the older boys are noticeable in light of the possible negative health consequences of iron overload.

Place, publisher, year, edition, pages
1995. Vol. 20, no 2, 215-24 p.
URN: urn:nbn:se:umu:diva-45434PubMedID: 7714689OAI: diva2:429445
Available from: 2011-07-04 Created: 2011-07-04 Last updated: 2015-03-16
In thesis
1. Cardiovascular risk indicators in adolescents: the Umeå youth study
Open this publication in new window or tab >>Cardiovascular risk indicators in adolescents: the Umeå youth study
1995 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Atherosclerotic cardiovascular diseases (CVD), particularly coronary heart disease (CHD) and cerebrovascular disease, are today major causes of death in the industrialised parts of the world. There are evidence to suggest that the atherosclerotic process starts in childhood, implying that preventive measures should be implemented already in children and adolescents.

The aim of this study was to examine CVD risk indicators and their determinants in healthy Swedish adolescents. The study population comprised 14- and 17-year-old boys and girls (n=1032), in the dty and surroundings of Umeå in northern Sweden.

Biochemical, anthropometric, and physiological parameters associated to CVD (s- lipoproteins and s-apolipoproteins, s-insulin, s-ferritin, anthropometric measurements, blood pressure, and physical fitness) were evaluated in relation to family history of CVD, weight and length at birth, infant feeding regimen, physical growth during infancy and childhood, current diet, physical activity, smoking, and educational level and occupation of the parents.

The main findings of the study were that, on average, total serum cholesterol (TC) values in boys and girls were at the same level as reported from other European countries. A family history of CVD, short duration of breast feeding, low attained height during infancy and childhood, high body mass index (BMI), and low physical fitness were all associated with an unfavourable serum lipid profile. The findings also showed that features typical of the insulin resistance syndrome are present already in adolescents. In boys, iron stores, estimated by serum ferritin, were related to BMI and physical fitness, in a similar way as well established CVD risk indicators. Compared to previous dietary studies in Sweden, mean relative (energy %) fat intake had decreased substantially although the mean relative intake of saturated fat was still rather high. For both boys and girls, reported relative energy intake (energy intake/estimated energy expenditure) decreased with increasing level of BMI. Furthermore, daily smoking was more common among adolescents from families with low socio-economic status (SES) but was most strongly associated to smoking in peers. Tobacco use was considerably higher among adolescents attending vocational programs at secondary high school as compared to theoretical programs. Daily smokers had a more unfavourable serum lipid profile compared to non-smokers. Low socio-economic status of the parents was related to higher BMI and low educational level to higher dietary fat intake in both boys and girls.

In conclusion, the findings of the study show that parameters linked to adult CVD when examined in adolescents, are related to family history, infant nutrition, previous physical growth, current body composition, physical fitness, physical activity, smoking, and social status and educational level of the parents.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 1995. 47 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 448
Cardiovascular risk factors, adolescents, serum lipids, serum insulin, serum ferritin, anthropometry, blood pressure, physical fitness, physical activity, diet, smoking, socio-economic status
National Category
Public Health, Global Health, Social Medicine and Epidemiology
urn:nbn:se:umu:diva-7540 (URN)91-7191-100-6 (ISBN)
Public defence
1995-12-08, Hörsal A, Samhällsvetarhuset, Umeå universitet, Umeå, 09:00
Available from: 2008-01-10 Created: 2008-01-10 Last updated: 2015-04-08Bibliographically approved

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