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Aims: To evaluate the effect of the administration of growth hormone on stature, body weight, and body composition in children aged between 4 and 10 years with Prader-Willi syndrome., Methods: Height, weight, and skinfold thickness were recorded in 25 children using standard anthropometric techniques at recruitment, and six months later, shortly before the start of daily subcutaneous injections of growth hormone. Body composition was assessed via a measurement of total body water using stable isotopes. Measurements were repeated at the end of the six months of growth hormone administration. Measurements of height, weight, and skinfold thickness were expressed as standard deviation scores (SDSs)., Results: There was a significant reduction in the percentage of body fat after growth hormone treatment; height velocity doubled during treatment; body weight did not change significantly when expressed as an SDS. Skinfold thickness at both the triceps and subscapular site decreased in absolute terms and when expressed as an SDS., Conclusions: These results indicate sufficient potential benefit to justify a more prolonged trial of growth hormone treatment and an exploration of different dosage regimens in children with Prader-Willi syndrome.

Objective: To investigate the ability of maternally-rated infant temperament to predict fatness and activity patterns in early childhood., Design: Longitudinal investigation of infants studied at 12 weeks and followed up at 2-3.5 y of age., Subjects: Thirty healthy full-term infants from the general population., Measurements: Body composition, behavioural activity and temperament at 12 weeks; anthropometry, body composition, diet and behavioural activity at follow-up., Results: Infant temperament predicted later behaviour and fatness. Easily soothable infants had leaner childhood skinfold thicknesses (P < 0.02) and were more active in childhood (P < 0.025). Infant distress was also related to childhood diet composition., Conclusions: Infant temperament can predict later body composition and behaviour. Both energy intake and energy expenditure may be mechanisms by which the relationship develops.

Studies of the effect of Kt/V (urea) on prediction of outcome in patients on peritoneal dialysis have shown conflicting results. We performed this study to examine the effects of the measurement of V by varying techniques on the calculation of Kt/V, using body water estimated by deuterium oxide dilution (D2O dilution) as the criterion method for estimation of V. Studies were performed in 20 peritoneal dialysis patients. Kt was calculated from 24-hour dialysate and urine collections and V estimated by D2O dilution, Watson formulae, 58% of body weight, bioelectrical impedance (BIA) and 73% of fat-free mass estimated by DEXA. V was also measured in 35 healthy controls. Hydration, expressed as body water by D2O dilution as a percentage of fat-free mass estimated by DEXA did not differ between peritoneal dialysis patients 71.0 (4.9)% and a healthy control group 71.1 (5.0)%. Mean Kt/V using D2O dilution was 2.14 (0.36). The other techniques resulted in a significantly lower Kt/V; Watson equations 2.01 (0.35), p < 0.005, BIA 1.93 (0.31), p < 0.0001, DEXA 2.06 (0.28), p < 0.05, 58% body weight 1.83 (0.38), p < 0.0001. Limits of agreement of Kt/V by the simpler techniques compared with D2O dilution [mean difference of (other techniques -D2O dilution) as % of mean values +/- 95% limits of agreement] were Watson equation -5.9 +/- 15.3%, BIA -10.1 +/- 15.5%, DEXA -3.4 +/- 13.5% and 58% body weight -9.9 +/- 23.5%. Differences in Kt/V from estimates using D2O dilution were significantly negatively correlated with body fat for 58% body weight (r = -0.80, p < 0.0001) and the Watson formulae (r = -0.49, p < 0.05) but not for BIA or DEXA. We conclude that clinically significant variation in Kt/V may occur due to the estimation of V and may account for the uncertainty of the value of Kt/V as a predictor of outcome in peritoneal dialysis patients. Estimating V by BIA and DEXA did not have any benefit over the Watson formulae in terms of agreement with D2O dilution, though did avoid systematic errors related to body fat. Estimation of V as a fixed proportion of body weight is clearly inferior to the other techniques.

1. Assessment of nutrition in patients with chronic renal failure by body composition measurement techniques may be affected by variable hydration. 2. This study aimed to derive a four-component model of body composition (consisting of fat, protein, total body water and body mineral) from a combination of dual-energy X-ray absorptiometry and total body water measured by deuterium oxide dilution, allowing assessment of body protein stores without the effect of variation in hydration. Patients with chronic renal failure on haemodialysis, peritoneal dialysis and conservative treatment and a control group were studied. Patients with chronic renal failure were at an 'ideal' state of hydration on clinical assessment. 3. Hydration was defined by total body water as a percentage of fat-free mass measured by dual-energy X-ray absorptiometry, and no differences were found between chronic renal failure subgroups and control subjects (except in the female undialysed chronic renal failure subgroup). Hydration was significantly correlated with percentage total body fat in the control groups but not in patients with chronic renal failure. 4. Lean tissue measured by dual-energy X-ray absorptiometry was significantly reduced in three of the six chronic renal failure groups compared with control subjects (male and female patients on haemodialysis and female patients on peritoneal dialysis). Protein estimated from the four-component model failed to detect these abnormalities. 5. Lean tissue measured by dual-energy X-ray absorptiometry in normal subjects strongly correlated with fat-free mass measured by total body potassium in normal subjects (male r = 0.91; female r = 0.89, both P < 0.0001). The correlation of protein estimated from the four-component model with fat-free mass measured by total body potassium was far weaker in male control subjects (r = 0.51, P < 0.05) and not significant in female control subjects (r = 0.38, P not significant). In the normal subjects protein estimated from the four-component model showed a much greater variation from protein estimated by total body potassium than did protein estimated simply as 27% of dual-energy X-ray absorptiometry fat-free mass minus total body mineral. 6. Hydration in patients with chronic renal failure in whom fluid balance is believed to be normal on clinical criteria does not differ from that in normal subjects. The combined model of dual-energy X-ray absorptiometry and total body water is not a useful method for the measurement of body protein.

Objective: To investigate whether any component of infant energy expenditure is related to fatness in early childhood, and whether infant fatness is related to childhood variables., Design: Longitudinal investigation of infants studied at 12 weeks and followed up at 2.5 to 3.5 years of age., Subjects: 30 healthy full-term infants selected from the general population., Measurements: Sleeping metabolic rate, total energy expenditure, anthropometry and behaviour at 12 weeks; anthropometry, body composition and behaviour in follow-up., Results: Energy expenditure at 12 weeks (minimal metabolism, total energy expenditure, energy expended on physical activity, behaviour) showed no relationship with later fatness. Infant fatness (skinfold thicknesses and percentage fat) showed in contrast a strong relationship with childhood fatness. Infant fatness also predicted childhood behaviour., Conclusions: These data do not support the theory that reduced energy expenditure in early infancy is related to later fatness. However, infant fatness influences both later fatness and activity patterns.

It has been suggested that infants born to overweight parents are at risk of becoming overweight because of reduced total energy expenditure (TEE). We therefore examined the relationship between infant TEE and parental nutritional status as assessed by body mass index (BMI) in a large sample of healthy infants. TEE was measured by the doubly labeled water method in 124 infants at 12 wk of age. Sleeping metabolic rate (SMR) was measured by indirect calorimetry in 70 of these infants. Indexes of physical activity were calculated as TEE/SMR and TEE-SMR. No aspect of infant energy expenditure was found to be related to parental BMI. Moreover, there was no difference between TEE of two subsets of infants born to parents with high and low BMIs. We therefore find no evidence for parental body composition being associated with reduced infant energy expenditure at 12 wk of age.

Total energy expenditure was measured in a cohort of 33 normal, full term infants at 12 weeks of age using the doubly labelled water technique. These data were related to Quetelet's index and the sum of the triceps and subscapular skinfold measurements at 9 months and 2 years of age. Correlation coefficients were used to determine the relationship between total energy expenditure and later indices of body composition. Total energy expenditure was expressed as kcal/kg per day; kcal/kg0.5 per day (in order to negate the effect of body weight) and kcal/kg fat free mass per day (in order to take into account body composition). Using this approach there was no relationship between the level of total energy expenditure at 12 weeks of age and later indices of body fatness. The highest correlation coefficient being 0.09 (n = 33, P greater than 0.10). These findings are contrary to recent reports that a reduced total energy expenditure is related to the development of obesity in certain selected groups of individuals.