Lena Hulthén

Serum Insulin-Like Growth Factor I Reference Values for an Automated Chemiluminescence Immunoassay System: Results from a Multicenter Study

Background: Analysis of insulin-like growth factor I in serum (S-IGF-I) is an integral component in the diagnosis of GH-related disorders and is going to be of interest in the diagnosis and follow-up of many disorders. The objective of the present study was to develop cross-sectional reference values for S-IGF-I measured by an automated chemiluminescence immunoassay (Nichols Advantage®). Methods: The study included samples from 3,961 healthy subjects (2,201 males, 1,760 females) aged 1 month to 88 years. Six laboratories were involved in this study and the samples were analyzed by one of seven automated immunoassay systems run in these laboratories. For data analysis, polynomial age and sex-specific models were fitted after transformation of S-IGF-I values. Results: The results show the well-known age dependency of S-IGF-I levels. At ages <20, higher S-IGF-I levels were seen in girls with an estimated mean peak of 410 µg/l at age 14 and an estimated mean peak of 382 µg/l at age 16 in boys. Thereafter, a rapid decrease was seen to approximately 25 years of age, followed by a slow age-dependent decrease. In adulthood, S-IGF-I in males were slightly, but significantly higher than in females. It could be shown that the mean values of some reference sample subgroups differed significantly from the total mean. However, the multicenter approach used in this study reduces the impact of systematic population, sample handling and laboratory differences on the calculated reference mean. Conclusion: The present study establishes age- and sex-specific reference values for a fully automated immunoassay system based on a large population of healthy subjects. The established reference values may be used for this immunoassay system in different laboratories provided that the systematic difference between systems is low.

Meal pattern, food choice, nutrient intake and lifestyle factors in The Göteborg Adolescence Study

Objective: To relate meal pattern of Swedish adolescents to food choice, nutrient intake and other lifestyle factors.Design: Cross-sectional study including diet history and interview about smoking, ethnicity, social factors and retrospectively collected data of menarche and growth.Setting: School setting, Göteborg, Sweden.Subjects: A total of 611 boys and 634 girls in grade 9 (15–16 y).Results: The majority of the students, 65% of the boys and 52% of the girls, consumed three main meals daily. The in-between meals, however, contributed the major part of the energy intake. The energy intake was 12.9±3.5 MJ (mean±s.d.) for boys and 9.0±2.5 MJ for girls. Irregular breakfast eating, 12% of the boys and 24% of the girls, was related to negative lifestyle factors where smoking was the strongest, odds ratio 3.8 (95% CI: 2.6–5.4) and to irregular intake of lunch and dinner. These boys and girls had a food choice including a higher percentage of energy from snack food (26% vs 20% and 19% in boys and girls respectively, all P<0.001), mostly consumed between the main meals. These groups had significantly lower intakes of micronutrients, but higher intakes of sucrose and alcohol compared to the groups with regular breakfast intake. Girls omitting breakfasts and lunches (8%) also had a less healthy food choice and the poorest nutrient intake. These girls had matured earlier, with menarche age of 12.2±1.1 y vs 12.9±1.0 y (P<0.001) in girls with regular main meal intake.Conclusions: Meal pattern with omission of breakfast or breakfast and lunch was related to a clustering of less healthy lifestyle factors and food choice leading to a poorer nutrient intake.Sponsorship: The Swedish Medical Research Council (project B94-19X-04721-19A), the Swedish Mill Industry and the Wilhelm and Martina Lundgren Foundation.

Effect of a mild infection on serum ferritin concentration—clinical and epidemiological implications

Objectives: To study the distribution of serum ferritin concentration in adolescent boys and girls with and without a preceding mild infection.Design: The prevalence of iron deficiency was studied in two representative samples. The first sample from 1990 comprised 207 boys and 220 girls. The second sample from 1994 included 620 boys and 624 girls. In total 1675 adolescents, 15–16 y old, 827 boys and 844 girls were studied.Results: A significant shift of serum ferritin concentration towards higher values was observed in those who reported an upper respiratory infection with fever during the preceding month (P<0.001). Significant differences were found between serum ferritin values in healthy, not infected adolescents and serum ferritin values in those with ongoing infection, both in boys and girls in the two materials (P<0.01), and in those with a mild infection during the preceding three weeks.Conclusions: The prevalence of recent infection should be included as information when trying to assess the prevalence of iron deficiency on the basis of serum ferritin measurements and when examining relationships between iron status and composition of the diet. The findings imply that differences in prevalence of iron deficiency between different studies might partly be explained by differences in prevalence of simple respiratory infections. The diagnostic sensitivity of the serum ferritin assay for iron deficiency, using conventional reference limits, decreases for subjects with recent such infections; similarly, there will be a decrease in the diagnostic specificity for haemochromatosis.Sponsorship: Swedish Medical Research Council (project B9519X-04721-20B) and Swedish Dairy Association, Stockholm.

Physical activity questionnaire for adolescents validated against doubly labelled water

Objective:To validate a physical activity questionnaire for adolescents (PAQA) adapted from the International Physical Activity Questionnaire (IPAQ).Design:Energy expenditure was measured during a 14-day period with doubly labelled water (DLW). PAQA was administered as an interview at the end of the period, asking for physical activity in school, during transportation and leisure-time, during a habitual week. Energy expenditure (EEPAQA) was calculated as the product of total physical activity+sleep and predicted resting metabolic rate, and was compared to energy expenditure from DLW (EEDLW), thermic effect of feeding excluded.Setting:Participants were recruited from grade 9 in a compulsory school in Göteborg, Sweden. All data were collected at school, and distribution of DLW and measuring of resting metabolic rate were performed at Sahlgrenska University Hospital.Subjects:A total of 33 adolescents (16 girls, 17 boys) 15.7 (0.4) y performed all measurements.Results:For the whole group, PAQA underestimated energy expenditure by 3.8 (1.7) MJ (P<0.001). There was a strong correlation (r=0.62, P<0.001) between EEPAQA and EEDLW, but not for boys (r=0.42, P=0.090) and girls (r=0.33, P=0.22) separately.Conclusions:PAQA is not able to predict energy expenditure in Swedish adolescents, largely explained by the amount of unreported time. The ability to rank adolescents energy expenditure is questioned because of the gender effect, although we found a strong correlation for the whole group.Sponsorship:Ingabritt and Arne Lundberg Foundation.

Cancer risk in Swedish women: the relation to size at birth

The relationship between fetal growth as indicated by weight and length at birth, and cancer risk in 1080 adult Swedish women was examined. Birth factors were retrieved from original midwife records for the years 1914, 1918, 1922 and 1930, and primary cancer cases were identified by matching with national and regional cancer registries through the year 1998. A positive and statistically significant increased risk for cancer was found with increasing birth weight or birth length for all site cancer and non-hormone related cancer, defined as all cancer sites excluding breast, uterus and ovary. Addition of factors suspected to influence cancer risk, maternal proteinuria, birth order, own parity and age at menarche, did not attenuate this relation. Previously only breast cancer has been reported to be related to size at birth in adult women and this is the first study to report that cancer sites other than the major hormone-related sites may be influenced by size at birth, as measured by either weight or length at birth; these findings warrant further investigation.

Free-living energy expenditure in children using multi-sensor activity monitors

AIMS To improve the energy expenditure algorithm of the activity monitor ActiReg, and to validate ActiReg and the activity monitor SenseWear in free-living children. METHODS The development of the ActiReg algorithm was performed in 20 healthy 11-13 years old children on treadmill walking and running with indirect calorimetry as reference. The original and new ActiReg algorithms and SenseWear using software versions InnerView 5.1 and 6.1 were validated in 20 healthy 14-15 years old children against doubly labelled water. RESULTS The new ActiReg algorithm improved the assessment of energy expenditure during walking and running, but the response from the monitor levelled off after 7 km h(-1). The new algorithm and InnerView 6.1 decreased the mean (sd) difference to doubly labelled water from 11 (25) (P<0.05) to 0 (22) kJ kg(-1) d(-1) for ActiReg, and from 17 (20) (P<0.01) to -10 (21) (P<0.05) kJ kg(-1) d(-1) for SenseWear. However, the correlations between energy expenditure and the individual error for the new ActiReg algorithm and InnerView 6.1 were r= -0.50 (P<0.05) and r= -0.73 (P<0.01). CONCLUSIONS The new ActiReg algorithm and InnerView 6.1 improved the activity monitors at group level, but the error was dependent on physical activity level. Both activity monitors need further developments for use in children.

Energy intake in Swedish adolescents: validation of diet history with doubly labelled water

Objective: To compare habitual energy intake (EI) estimated from diet history (DH) with total energy expenditure (TEE) measured with doubly labelled water (DLW) in adolescents.Design: DH included a detailed questionnaire and an interview. TEE was measured during a 14-day period. Adequate (AR), under- (UR) and over-reporters (OR) were defined from the ratio EI/TEE: AR 0.84–1.16, UR <0.84 and OR >1.16.Setting: Participants were recruited from grade 9 in a compulsory school in Göteborg, Sweden. All data were collected at school and DLW dosages were distributed at Sahlgrenska University Hospital.Subjects: A total of 35 adolescents (18 boys, 17 girls), 15.7 (0.4) y.Results: EI was 11.0 (3.6) MJ and TEE was 11.4 (2.1) MJ (P=0.42). DH was able to rank EI compared to TEE (Spearmans r=0.59, P⩽0.001). For girls, EI was 18% lower (P=0.0067) and for boys, EI was 7% higher (P=0.26) compared to TEE. The 95% limits of agreement for difference between TEE and EI were −5.6 to 6.5 MJ. In total, 20 subjects were defined as AR (57%), nine as UR (26%) and six as OR (17%). Energy from in-between meals was 33% lower (P=0.0043) in UR girls and 57% higher (P=0.026) in OR boys, compared to adequate reporting girls and boys, respectively. In UR girls, energy-adjusted intake (10 MJ) of specific foods did not differ significantly, fat was lower and carbohydrate and vitamin C were higher compared to AR girls (all P<0.05). OR boys had no significant differences in food and nutrient intake in 10 MJ compared to AR boys.Conclusion: The diet history was able to capture EI for the group and to rank subjects. There was a wide individual range in reporting- accuracy related to gender.Sponsorship: The Ingabritt and Arne Lundberg Foundation, The Wilhelm and Martina Lundgren Foundation.

Energy Cost in Children Assessed by Multisensor Activity Monitors

PURPOSE The SenseWear Pro2 Armband (SWA; BodyMedia, Inc., Pittsburg, PA), the Intelligent Device for Energy Expenditure and Activity (IDEEA; Minisun LLC, Fresno, CA), and the ActiReg (AR; PreMed AS, Oslo, Norway) were compared with indirect calorimetry to determine the ability of these devices to assess energy cost in children during resting and different physical activities. METHODS Fourteen children, 11-13 yr old, wore the SWA, the IDEEA, and the AR during resting, sitting, stationary bicycling, jumping on a trampoline, playing basketball, stair walking, and walking/running along a 50-m track. The Oxycon Mobile portable metabolic system (VIASYS Healthcare, Conshohocken, PA) was used as the criterion method for energy cost. RESULTS For resting and sitting, the three activity monitors showed comparable results, but none of them accurately assessed energy cost for stationary bicycling, jumping on a trampoline, or playing basketball. The IDEEA was the only activity monitor that accurately assessed energy cost for stair walking. Also, the IDEEA showed a close estimate of energy cost across the walking and the running intensities, whereas the SWA accurately assessed energy cost for slow to normal walking but showed increased underestimation of energy cost with increasing speed. The AR overestimated energy cost during walking and during slow running but did not respond to increasing running speed. CONCLUSIONS To be able to capture childrens physical activity, all three activity monitors need to be further developed. Overall, the IDEEA showed the highest ability to assess energy cost in this study, but SWA may be more feasible for use in children under free-living conditions.

UVB therapy increases 25(OH) vitamin D syntheses in postmenopausal women with psoriasis.

Background: Vitamin D3 is produced in the epidermis by ultraviolet (UV) radiation (290–315 nm) of 7‐dehydrocholesterol. A similar range of 290–320 nm (broadband UVB) has been successfully used for years to treat psoriasis. The aim of this study was to investigate whether UVB therapy was able to influence vitamin D synthesis in psoriasis patients.

The validation of using serum iron increase to measure iron absorption in human subjects

The objectives of the present study were to study the correlation between the change in serum Fe and Fe absorption when administering 100 mg Fe (as FeSO4) orally, and to study the correlation between the absorption from a 3 mg and a 100 mg Fe (as FeSO4) dose. The study was conducted in a group of eleven male blood donors, without any evident infection, who had given blood 8 weeks before the study. On three consecutive mornings the subjects were served a wheat roll fortified with Fe. On the first 2 d the roll was fortified with 3 mg Fe labelled with 59Fe; on day 3 the roll was fortified with 100 mg Fe labelled with 55Fe. The serum Fe response to the 100 mg dose was followed for 6 h. Fe absorption was measured by whole-body counting. High correlations were seen between the absorption of Fe and the change in serum Fe after 100 mg Fe (r2 0.94, P<0.001), between the absorption from 3 mg and 100 mg Fe (r2 0.88, P<0.001), and between the absorption from 3 mg Fe and change in serum Fe after 100 mg Fe (r2 0.90, P<0.001). This strengthens the evidence that it is possible to use the change in serum Fe as a measure of Fe absorption, e.g. when establishing the relative bioavailability for Fe powders. The results also imply that the induced serum Fe increase following 100 mg Fe added to a food could predict the Fe absorption of a small dose of Fe added to the same meal.