Changes in body composition, resting energy expenditure, and thermic effect of food in short children on growth hormone therapy

Effect of growth hormone treatment on energy expenditure and its relation to first-year growth response in children

PURPOSE

The effects of growth hormone (GH) treatment on linear growth and body composition have been studied extensively. Little is known about the GH effect on energy expenditure (EE). The aim of this study was to investigate the effects of GH treatment on EE in children, and to study whether the changes in EE can predict the height gain after 1 year.

METHODS

Total EE (TEE), basal metabolic rate (BMR), and physical activity level (PAL) measurements before and after 6 weeks of GH treatment were performed in 18 prepubertal children (5 girls, 13 boys) born small for gestational age (n = 14) or with growth hormone deficiency (n = 4) who were eligible for GH treatment. TEE was measured with the doubly labelled water method, BMR was measured with an open-circuit ventilated hood system, PAL was assessed using an accelerometer for movement registration and calculated (PAL = TEE/BMR), activity related EE (AEE) was calculated [AEE = (0.9 × TEE) - BMR]. Height measurements at start and after 1 year of GH treatment were analysed. This is a 1-year longitudinal intervention study, without a control group for comparison.

RESULTS

BMR and TEE increased significantly (resp. 5% and 7%). Physical activity (counts/day), PAL, and AEE did not change. 11 out of 13 patients (85%) with an increased TEE after 6 weeks of GH treatment had a good first-year growth response (∆height SDS > 0.5).

CONCLUSIONS

GH treatment showed a positive effect on EE in prepubertal children after 6 weeks. No effect on physical activity was observed. The increase in TEE appeared to be valuable for the prediction of good first-year growth responders to GH treatment.

Growth hormone therapy in children with idiopathic short stature - the effect on appetite and appetite-regulating hormones: a pilot study

AIM

To investigate the effect of growth hormone (GH) therapy on appetite-regulating hormones and to examine the association between these hormones and the response to GH, body composition, and resting energy expenditure (REE).

METHODS

Nine pre-pubertal children with idiopathic short stature underwent a standard meal test before and 4 months following initiation of GH treatment. Ghrelin, GLP-1, leptin, and insulin levels were measured; area under the curve (AUC) was calculated. Height, weight, body composition, REE, and insulin-like growth factor levels were recorded at baseline and after 4 and 12 months.

RESULTS

Following 4 months of GH therapy, food intake increased, with increased height-standard deviation score (SDS), weight-SDS, and REE (p < .05). Significant changes in appetite-regulating hormones included a decrease in postprandial AUC ghrelin levels (p = .045) and fasting GLP-1 (p = .038), and an increase in fasting insulin (p = .043). Ghrelin levels before GH treatment were positively correlated with the changes in weight-SDS (fasting: r = .667, p = .05; AUC: r = .788, p = .012) and REE (fasting: r = .866, p = .005; AUC: r = .847, p = .008) following 4 months of GH therapy. Ghrelin AUC at 4 months was positively correlated with the changes in height-SDS (r = .741, p = .022) and fat-free-mass (r = .890, p = .001) at 12 months of GH treatment.

CONCLUSIONS

The reduction in ghrelin and GLP-1 following GH treatment suggests a role for GH in appetite regulation. Fasting and meal-AUC ghrelin levels may serve as biomarkers for predicting short-term (4 months) changes in weight and longer term (12 months) changes in height following GH treatment. The mechanisms linking GH with changes in appetite-regulating hormones remain to be elucidated.

ABBREVIATIONS

SDS: standard deviation score; REE: resting energy expenditure; SMT: standard meal test; AUC: area under the curve; ISS: idiopathic short stature; SGA: small for gestational age; FFM: fat-free-mass; FM: fat mass; EER: estimated energy requirements; DRI: dietary reference intakes; IQR: inter-quartile range.

Ketogenic diet treatment in adults with refractory epilepsy: a prospective pilot study

PURPOSE

To assess the efficacy of ketogenic diet (KD) in adults with refractory epilepsy.

METHODS

Eligible subjects were 18-45 years old with at least two monthly focal seizures (with or without secondary generalization) documented by 8 weeks' follow-up. Classic form of KD treatment (90% fat) was planned for 12 weeks: daily seizure diaries were kept and measurements of the urinary ketones were recorded. Blood studies were done monthly and resting energy expenditure (REE), substrate utilization; body composition and quality of life (QOL) were measured before and after intervention.

RESULTS

Nine patients were enrolled (average age 28+/-6 years; seven women). Only two subjects concluded the study per protocol due to an early drop-out. The average length of KD treatment was 8+/-4 weeks (two patients completed 12 weeks of KD; feelings of hunger and lack of efficacy resulted in withdrawal of the rest). The two patients who concluded the study had a more than 50% reduction in the frequency of the seizures. The others experienced no improvement. Adherence to the KD protocol (100%) was documented by constant ketonuria and increased fat utilization as indicated by the change in respiratory quotient (p<0.031). The KD increased the cholesterol levels (mainly LDL; p=0.0001).

CONCLUSIONS

In our experience with relatively small adult population, adherence to KD is difficult. In patients who had compliance over 3 weeks (6/8), KD does not seem to have a significant effect. Yet, the significant reduction in the two patients who concluded the study per protocol may indicate that some patients may benefit from this diet. Significant increase in LDL levels and the unlikable dietary changes are additional impediments to its implementation among adults with refractory epilepsy.

Endocrine control of body composition in infancy, childhood, and puberty

Body composition exhibits marked variations across the early human lifetime. The precise physiological mechanisms that drive such developmental adaptations are difficult to establish. This clinical challenge reflects an array of potentially confounding factors, such as marked intersubject differences in tissue compartments; the incremental nature of longitudinal intrasubject variations in body composition; technical limitations in quantitating the unobserved mass of mineral, fat, water, and muscle ad seriatim; and the multifold contributions of genetic, dietary, environmental, hormonal, nutritional, and behavioral signals to physical and sexual maturation. From an endocrine perspective (reviewed here), gonadal sex steroids and GH/IGF-I constitute prime determinants of evolving body composition. The present critical review examines hormonal regulation of body composition in infancy, childhood, and puberty.

Hormonal changes during puberty and their relationship to fat distribution

In adults, abdominal visceral adiposity is related to an increased risk of cardiovascular diseases, Type 2 diabetes mellitus, and stroke. The antecedents of these conditions likely begin with the alterations in body fat distribution during childhood and adolescence. The sexually dimorphic alterations in fat distribution are influenced by sex differences in hormone concentrations, anatomical differences in the number and density of specific hormone receptors, capillary blood flow, and the activity of enzymes promoting lipid synthesis or degradation. Hormones influencing the amount and regional distribution of adipose tissue during puberty include cortisol, insulin, growth hormone, and the sex steroids. Cortisol and insulin promote fat deposition while the sex steroids and GH stimulate lipolysis. An overly sensitive hypothalamic-pituitary-adrenal axis may exist in obesity and disrupt the balance between the lipogenic effects of cortisol and insulin and the lipolytic effects of sex steroids and growth hormone. Leptin is released from the adipocytes and may act as a metabolic signal to the hypothalamic areas controlling satiety, energy expenditure, and the regulation of cortisol, insulin, sex steroid and growth hormone release. The complex issues of the hormonal control of alterations in body fat distribution during puberty are developed and a working model is proposed. Am. J. Hum. Biol. 11:209-224, 1999. Copyright 1999 Wiley-Liss, Inc.

A Hattori chart analysis of body mass index in infants and children

BACKGROUND

Body mass index (BMI) is widely used as an index of fatness in paediatrics, but previous analysis of the BMI-fatness relationship has been insufficient.

OBJECTIVE

To consider the effects of variation in fat-free mass (FFM) and fat mass (FM) on BMI in infants, children and Fomon's reference child (Am J Clin Nutr 1982; 35: 1169-1175).

SUBJECTS

42 infants aged 12 weeks; 64 children aged 8-12 y; Fomon's reference child.

METHODS

FFM was measured by deuterium dilution. FFM index (FFMI) and FM index (FMI) were calculated. The effects of variation in FFM and FM on BMI were explored using Hattori's body composition chart (Am J Hum Biol 1997; 9: 573-578).

RESULTS

In both infancy and childhood, a given BMI can embrace a wide range of percentage body fat. At both time points, the s.d. of FFMI was > 60% of the s.d. of FMI. Graphic analysis differentiated the effects of lean tissue and fat deposition on BMI with age in the reference child.

CONCLUSION

Although valuable for assessing short-term changes in nutritional status in individuals, and for comparing mean relative weight between populations, BMI is of limited use as a measure of body fatness in individuals in both infancy and childhood. The development of BMI with age may be disproportionately due to either FFM and FM at different time points.

Body composition in children receiving recombinant human growth hormone after renal transplantation

BACKGROUND

Recombinant human growth hormone (rhGH) is an anabolic hormone promoting protein synthesis in various tissues. Therefore, changes in body composition may be expected during rhGH treatment.

METHODS

We studied changes in body composition during two years of rhGH treatment in 21 children after at least one year with a functioning renal transplant. The mean +/- SD age was 12.9+/-2.5 years at the start of rhGH therapy. A whole body, dual energy X-ray absorptiometry (DEXA) exam was performed before the initiation of rhGH therapy (T0), and was repeated at one and two year intervals after initiation of the therapy (T1 and T2, respectively).

RESULTS

Lean body mass increased by a median of 0.48 SDS during the first year of treatment (P = 0.022), and the median increase during two years of therapy was 0.36 SDS (P = 0.061). On the contrary, the median fat body mass decreased by 2.17 SDS during the T0 to T1 period (P = 0.04) and by 1.99 SDS during the T0 to T2 period (P = 0.055). The index for fat body mass/lean body mass (FBM/LBM) decreased by a median of 5.3% during T0 to T1 (P < 0.001), however, a slower but still significant decrease by a median of 4.2% was noted at T2 (P < 0.05). Bone mass content did not change significantly during rhGH treatment. The medians in caloric and protein intakes were stable during rhGH treatment.

CONCLUSION

A significant increase of lean body mass and a decrease of fat body mass was noted during rhGH therapy in children after renal transplantation.

Alterations in growth and body composition during puberty: III. Influence of maturation, gender, body composition, fat distribution, aerobic fitness, and energy expenditure on nocturnal growth hormone release

We examined the relationships among gender, sexual maturation, four-compartment model estimates of body composition, body fat distribution (magnetic resonance imaging for abdominal visceral fat and anthropometrics), aerobic fitness, basal and total energy expenditure, and overnight GH release in an ultrasensitive chemiluminescence assay in healthy prepubertal and pubertal boys (n = 18 and 11, respectively) and girls (n = 12 and 18, respectively). Blood samples were withdrawn every 10 min from 1800-0600 h to determine the area under the serum GH-time curve (AUC), sum of the GH peak heights (sigma GH peak heights), and the mean nadir GH concentration. GH release was greater in the pubertal than prepubertal subjects due to an increase in sigma GH peak heights (43.8 +/- 3.6 vs. 24.1 +/- 3.5 ng.mL-1, P = 0.0002) and mean nadir (1.7 +/- 0.2 vs. 0.7 +/- 0.2 ng.mL-1, P = 0.0002), but not peak number (4.3 +/- 0.2 vs. 4.5 +/- 0.2). The girls had a greater sigma GH peak heights (39.0 +/- 3.5 vs. 28.8 +/- 3.6 ng.mL-1, P = 0.05) and mean nadir concentration (1.4 +/- 0.2 vs. 0.9 +/- 0.2 ng.mL-1, P = 0.05) than the boys. Significant inverse relationships existed between sigma GH peak heights (r = -0.35, P = 0.06) or mean nadir (r = -0.39, P = 0.04) and four-compartment percent body fat for all boys but not for all girls or when combining all subjects. For all girls, significant inverse relationships existed between sigma GH peak heights (r = -0.39, P = 0.03) or mean nadir (r = -0.37, P = 0.04) and waist/hip ratio. Similar inverse relationships in all boys or all subjects were not significant. Forward stepwise regression analysis determined that bone age (i.e. maturation, primary factor) and gender were the significant predictors of AUC, sigma GH peak heights, and mean nadir. The influence of maturation reflects rising sex steroid concentrations, and the gender differences appear to be because of differences in estradiol concentrations rather than to body composition or body fat distribution.