Body composition in children based on anthropometric data

Knowledge of the body composition in terms of fat and fat-free mass is used in paediatrics to estimate a child’s nutritional status. To obtain the fat content or protein content sophisticated techniques exist. These techniques are often difficult to apply in daily practice. An anthropometric approach is therefore relevant because of its simplicity. In this study skinfold thicknesses and mid-upperarm circumference are presented as reference values and used to derive the fat-free mass fraction of the body and the arm muscle area. Conclusion Despite the shortcomings of an anthropometric approach in estimating the fraction of fat-free mass or protein content, its simplicity makes the method of calculating these fractions on skinfold thicknesses and mid-upperarm circumference valuable to apply in daily paediatric practice. Received: 1 December 1995 Accepted: 4 April 1996     

Final height in girls with turner syndrome after long-term growth hormone treatment in three dosages and low dose estrogens

Although GH treatment for short stature in Turner syndrome is an accepted treatment in many countries, which GH dosage to use and which age to start puberty induction are issues of debate. This study shows final height (FH) in 60 girls with Turner syndrome treated in a randomized dose-response trial, combining GH treatment with low dose estrogens at a relatively young age. Girls were randomly assigned to group A (4 IU/m(2).d; approximately 0.045 mg/kg/d), group B (first year, 4 IU/m(2).d; thereafter 6 IU/m(2).d), or group C (first year, 4 IU/m(2).d; second year, 6 IU/m(2).d; thereafter, 8 IU/m(2).d). After a minimum of 4 yr of GH treatment, at a mean age of 12.7 +/- 0.7 yr, low dose micronized 17beta-estradiol was given orally. After a mean duration of GH treatment of 8.6 +/- 1.9 yr, FH was reached at a mean age of 15.8 +/- 0.9 yr. FH, expressed in centimeters or SD score, was 157.6 +/- 6.5 or -1.6 +/- 1.0 in group A, 162.9 +/- 6.1 or -0.7 +/- 1.0 in group B, and 163.6 +/- 6.0 or -0.6 +/- 1.0 in group C. The difference in FH in centimeters, corrected for height SD score and age at start of treatment, was significant between groups A and B [regression coefficient, 4.1; 95% confidence interval (CI), 1.4, 6.9; P < 0.01], and groups A and C (coefficient, 5.0; 95% CI, 2.3, 7.7; P < 0.001), but not between groups B and C (coefficient, 0.9; 95% CI, -1.8, 3.6). Fifty of the 60 girls (83%) had reached a normal FH (FH SD score, more than -2). After starting estrogen treatment, the decrease in height velocity (HV) changed significantly to a stable HV, without affecting bone maturation (change in bone age/change in chronological age). The following variables contributed significantly to predicting FH SD score: GH dose, height SD score (ref. normal girls), chronological age at start of treatment, and HV in the first year of GH treatment. GH treatment was well tolerated. In conclusion, GH treatment leads to a normalization of FH in most girls, even when puberty is induced at a normal pubertal age. The optimal GH dosage depends on height and age at the start of treatment and first year HV.     

Final height in central precocious puberty after long term treatment with a slow release GnRH agonist

OBJECTIVE: To study the resumption of puberty and the final height achieved in children with central precocious puberty (CPP) treated with the GnRH agonist triptorelin. PATIENTS: 31 girls and five boys with CPP who were treated with triptorelin 3.75 mg intramuscularly every four weeks. Girls were treated for a mean (SD) of 3.4 (1.0) years and were followed up for 4.0 (1.2) years after the treatment was stopped. RESULTS: The rate of bone maturation decreased during treatment and the predicted adult height increased from 158.2 (7.4) cm to 163.9 (7.5) cm at the end of treatment (p < 0.001). When treatment was stopped bone maturation accelerated, resulting in a final height of 161.6 (7.0) cm, which was higher than the predicted adult height at the start of treatment (p < 0.001). Height at the start of treatment was the most important factor positively influencing final height (r = 0.75, p < 0.001). Bone age at cessation of treatment negatively influenced final height (r = -0.52, p = 0.03). A negative correlation between bone age and height increment after discontinuation of treatment was observed (r = -0.85, p = 0.001). Residual growth capacity was optimal when bone age on cessation of treatment was 12 to 12.5 years. Body mass index increased during treatment and remained high on cessation. At final height, the ratio of sitting height to subischial leg length was normal. Menarche occurred at 12.3 (1.1) years, and at a median (range) of 1.1 (0.4 to 2.6) years after treatment was stopped. The ovaries were normal on pelvic ultrasonography. CONCLUSIONS: Treatment of CPP with triptorelin increases final height, with normal body proportions, and seems to increase body mass index. The best results were achieved in girls who were taller at the start of treatment. Puberty was resumed after treatment, without the occurrence of polycystic ovaries.     

Physical activity levels in children and adolescents

BACKGROUND: Reference data for physical activity level (PAL) and activity-related energy expenditure (AEE) are needed for a better understanding of the effect of activity on childhood health, growth and development OBJECTIVE: Data from 17 studies measuring TDEE (TDEE) with doubly labelled water DLW were combined to construct a reference line for PAL and AEE as a function of age. DESIGN: A total of 17 studies from the literature were analyzed; 17 on girls and 16 on boys. Children were aged 3-16 y and of Caucasian origin. Weighted least-squares regression was used to obtain reference lines for PAL and AEE as a function of age and gender. The relative numbers of children per study were used as a weighting factor. Basal metabolic rate (BMR) or nonfasted (NF) resting metabolic rate and sex were included in the analysis. RESULTS: Although there was no difference in PAL between boys and girls, a significant difference in AEE was found between the two sexes. PAL: 0.025 x age+1.40. AEE (MJ/day): boys 0.30 x age+0.025; girls 0.21 x age+0.33. If BMR is measured under NF conditions, the obtained value has to be reduced by 0.21 for PAL and 0.75 MJ/day for AEE. No relation was found between AEE/kg and age. CONCLUSIONS: PAL and AEE were found to increase with age, showing the importance of age-dependent recommendations. Recommendations for AEE need to be differentiated for sex. To compare PAL and AEE between studies, the measurement conditions of BMR have to be taken into account. The increase in PAL and AEE values can be attributed to an increase in weight, because there was no relation between AEE/kg and age.     

Physical activity as measured by accelerometry in children receiving growth hormone

AIM: Parents of children treated with growth hormone (GH) frequently report to the paediatrician that their children have become more physically active. In the present study, activity patterns of GH-treated children were measured and compared to those of healthy controls. METHODS: Subjects were 25 children at the start of GH treatment (age 8.4 +/- 2.6 y) and 19 age- and gender-matched controls (age 8.8 +/- 3.2 y). Physical activity was assessed with a tri-axial accelerometer for movement registration over two separate 2-wk intervals, one before the start of GH treatment and one 2 wk after the start of treatment. GH-treated subjects were categorized as poor responders (change in height over 1 y <0.7 SDS, n = 15) or good responders (change in height over 1 y >0.7 SDS, n = 10). RESULTS: Before therapy, good responders showed a significantly lower physical activity compared to healthy controls, spending significantly less time on high-intensity activities. This difference disappeared 2 wk after the start of therapy. Physical activity in poor responders was not significantly different from controls before and after 2 wk of GH therapy. CONCLUSION: Children who respond well to GH therapy (change in height >0.7 SDS) showed a reduced amount of physical activity before therapy, which was normalized after 2 wk of GH therapy.     

Short-term effects of growth hormone on body composition as a predictor of growth

The objective of this study was to investigate whether short-term changes in metabolism, as a result of GH therapy, could be used to predict its growth effect after 1 yr. Twenty-eight children (8.7 +/- 2.8 yr) were selected, based on anthropometric criteria characterizing GH-deficient patients. In addition, 21 healthy, age- and sex-matched controls (8.9 +/- 3.1 yr) were included. Total body water (TBW) and height were measured before and at 6 wk and 1 yr after the start of treatment. After 1 yr of treatment, patients were divided into good and poor responders, based on a change in height of at least 0.7 SD. Because individuals of different heights were compared, changes in TBW after 6 wk were corrected for height(2), in accordance with the body mass index. Eighty percent of the children who showed a good response to GH therapy had a change in TBW divided by height(2) exceeding the 2 SD reference line of the controls. In contrast, poor responders did not differ from controls. Maximum GH concentrations found during endocrine tests were not significantly different between good and poor responders. Changes in body composition data, after 6 wk, proved valuable in identifying good responders to GH therapy.