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PubMed2002

Body composition and hormonal responses to a carbohydrate-restricted diet.

The few studies that have examined body composition after a carbohydrate-restricted diet have reported enhanced fat loss and preservation of lean body mass in obese individuals. The role of hormones in mediating this response is unclear. We examined the effects of a 6-week carbohydrate-restricted diet on total and regional body composition and the relationships with fasting hormone concentrations. Twelve healthy normal-weight men switched from their habitual diet (48% carbohydrate) to a carbohydrate-restricted diet (8% carbohydrate) for 6 weeks and 8 men served as controls, consuming their normal diet. Subjects were encouraged to consume adequate dietary energy to maintain body mass during the intervention. Total and regional body composition and fasting blood samples were assessed at weeks 0, 3, and 6 of the experimental period. Fat mass was significantly (P <or=.05) decreased (-3.4 kg) and lean body mass significantly increased (+1.1 kg) at week 6. There was a significant decrease in serum insulin (-34%), and an increase in total thyroxine (T(4)) (+11%) and the free T(4) index (+13%). Approximately 70% of the variability in fat loss on the carbohydrate-restricted diet was accounted for by the decrease in serum insulin concentrations. There were no significant changes in glucagon, total or free testosterone, sex hormone binding globulin (SHBG), insulin-like growth factor-I (IGF-I), cortisol, or triiodothyronine (T(3)) uptake, nor were there significant changes in body composition or hormones in the control group. Thus, we conclude that a carbohydrate-restricted diet resulted in a significant reduction in fat mass and a concomitant increase in lean body mass in normal-weight men, which may be partially mediated by the reduction in circulating insulin concentrations.

3-Hydroxybutyric Acid↗

PubMed2005

Gender-related changes in body composition, muscle strength and power output after a short-term multidisciplinary weight loss intervention in morbid obesity.

Obese men and women have notably different body composition, which contributes to a different functional motor impairment, but it is unknown whether they respond differently to the same intervention for body weight (BW) reduction and motor capability improvement. The aim of this investigation was to compare changes in body composition, strength production and power output observed in severely obese men and women after a BW reduction intervention, and to test the hypothesis that changes in body composition may be related to changes in motor functionality. Ninety-five obese men and women of the same age (29.3 +/- 7.0 SD yr) and body mass index (41.2 +/- 4.4 kg/m2) participated in a short-term (3 week) mass reduction program (5 days/week) entailing exercise (aerobic and strength training) and energy-restricted diet. BW and body composition, maximum voluntary total isotonic strength (ST), and maximum leg power output (W) were evaluated before and after the program. After the intervention, BW decreased significantly in both men and women, but males lost a significantly higher amount of their initial BW than females (5.12 +/- 0.91 vs 4.27 +/- 1.42%, p<0.01). In men the BW loss was composed by a similar amount of fat mass (FM) and fat-free mass (FFM), whereas women lost FM almost entirely. Both men and women significantly improved ST after the intervention, but no difference in improvement was detected between genders, while W increased significantly in females (p<0.001), and no change was detected in males, although W per unit BW and FFM increased significantly in both genders (p<0.05-0.001). In spite of the positive correlation of ST and W with FFM (p<0.001), there was no detectable relation between the changes in body composition and those in motor performance, the improvement in ST and W being better attributable to factors other than muscle mass change. The present diet/exercise intervention induced significant effects on BW changes and composition as well as on ST and W, with a different impact in males and females.

Adult↗

PubMed1999

Body composition determined by six different methods in women bilaterally adrenalectomized for treatment of Cushing's disease.

In 14 women, aged 47.2 +/- 10.5 yr, bilaterally adrenalectomized for Cushing's disease 13.6 +/- 7.7 yr before, all receiving conventional doses of glucocorticoid and mineralocorticoid substitution, body composition was studied with regard to body fat, body fat distribution, fat-free mass, and bone mineral density. The data were compared with those of 14 healthy women of similar age, body mass index, and menopausal state. Five different body composition measurement methods were compared, i.e. body densitometry by underwater weighing (UWW), total body water measurement by deuterium dilution (D2O dilution), dual energy x-ray absorptiometry (DXA), bioelectrical impedance spectrometry (BIS), and skinfold measurements, using a four-component model (4C-model) as the reference method. In the patients the percent body fat was significantly higher than that in the controls as determined by all methods, whereas fat-free mass was significantly lower when measured with the 4C-model, UWW, D2O dilution, DXA, or BIS. Measured by DXA, the percent trunk fat, estimated as [fat mass of the trunk (g)/total fat mass (g)] x 100%, was significantly higher in the patients than in the controls (39.3 +/- 6.4% and 29.9 +/- 7.8%, respectively; P < 0.001). Measured by DXA, there was no difference in total bone mineral density between the groups. Differences between the 4C-model, UWW, D2O dilution, and DXA for determination of percent body fat were rather small. Skinfold measurements and BIS results, however, deviated substantially from those obtained using the 4C-model. The study indicates that adrenalectomized patients receiving conventional glucocorticoid substitution have increased body fat percentages with a centripetal fat distribution and lowered fat-free mass, but normal bone mineral density. Furthermore, the study indicates that for clinical practice, DXA, D2O dilution, UWW, and the 4C-model can be used for determination of body composition in this patient group, whereas the more convenient bedside methods, BIS and skinfold measurements, did not give reliable results. We suppose that glucocorticoid overreplacement in adrenalectomized patients might be the cause of their abnormal body composition, although GH deficiency after pituitary surgery could have played a contributory role in some of the patients.

Absorptiometry, Photon↗

PubMed2003

Validation and calibration of DEXA body composition in mice.

Validated methods of determining murine body composition are required for studies of obesity in mice. Dual-energy X-ray absorptiometry (DEXA) provides a noninvasive approach to assess body fat and lean tissue contents. Similar to DEXA analyses in other species, body fat measurements in mice show acceptable precision but suffer from poor accuracy. Because fat and lean tissues each contain various components, these inaccuracies likely result from selection of inappropriate calibration standards. Analysis of solvents showed that the PIXImus2 DEXA gave results consistent with theoretical calculations. Male mice weighing 26-60 g and having body fat percentages ranging from 3 to 49% were analyzed by both PIXImus2 DEXA and chemical carcass analysis. DEXA overestimated mouse fat content by an average of 3.3 g, and algorithms were generated to calculate body fat from both measured body fat values and the measured ratio of high- to low-energy X-ray attenuations. With calibration to mouse body fat content measured by carcass analysis, the PIXImus2 DEXA gives accurate body composition values in mice.

Absorptiometry, Photon↗

PubMedDate not supplied

[Body composition analysis in ballet dancers].

INTRODUCTION: The aim of this study was to evaluate and compare the nutritional status and body composition in female ballet dancers and a group of non-athletic female controls. MATERIALS AND METHODS: The study group consisted of 30 female ballet dancers, aged 17.4 +/- 2.01, whereas the control group included 30 non-athletic female examinees, aged 18.00 years on average. Height and weight were measured and body mass index (BMI) was calculated in all subjects. Body composition was estimated using the bioelectrical impedance method. RESULTS: Body composition analysis of ballet dancers revealed significantly lower values of body fat mass compared to the control group (18.85 +/- 4.50% vs. 23.41 +/- 4.34). Most examinees in both groups were of normal weight. 50% of ballet dancers and 23.33% of examinees in the control group were underweight, while overweight subjects were registered only in the control group. Most underweight ballet dancers had lower body fat mass, whereas majority of underweight examinees in the control group presented with normal body fat mass. Normal-weight obesity was established in 40.91% candidates in the control and 6.67% in the study group. CONCLUSION: Ballet dancers had significantly lower values of body mass and BMI, compared to the study group. In order to prevent very serious complications caused by changes in size and proportion of some body compartments, it is necessary to carry out assessment of body composition more often in high-risk groups, such as the study group of ballet dancers.

Adolescent↗

PubMed1994

Total exchangeable sodium related to body composition in patients with conventional or reservoir ileostomy.

Decreased exchangeable body sodium might be a consequence of proctocolectomy and construction of an ileal reservoir. To investigate this, 35 patients with ulcerative colitis and conventional ileostomy were studied before and after conversion to continent ileostomy and compared with 25 unoperated subjects as reference. The sodium urinary excretion varied between 7 and 229 and 1 and 217 mmol/24 h in patients with conventional and reservoir ileostomy, respectively. The total exchangeable sodium was measured and related to body composition estimated from body weight, total body water, and total body potassium. No effect on exchangeable sodium was observed after conversion: 3100 mmol and 2990 mmol, respectively. Patients with ileostomy, regardless of type, did not differ from reference subjects in their exchangeable sodium when related to total body water. A larger variation of total exchangeable sodium related to total body water suggests unstable sodium homeostasis in patients with ileal reservoir compared with reference subjects.

Adult↗

PubMed1990

Use of total-body electrical conductivity for the assessment of body composition in middle-aged and elderly individuals.

Body composition was predicted for 114 middle-aged and elderly individuals aged 35-90 y by using total-body electrical conductivity (TOBEC), densitometry, and hydrometry. Highly significant correlations were achieved between the TOBEC Phase value and fat-free mass (FFM) determined by densitometry (FFMd) and hydrometry (FFMdw) with values ranging from 0.713 to 0.981. TOBEC predicted FFM (FFMT) was consistently higher than either FFMd or FFMdw for both men and women in all age groups. A theoretical calculation of percent body fat was performed with a three-component model with body density, total body water, and bone mineral content. The recalculation of fat was used to estimate a new FFM (FFMnew). These calculations resulted in a decrease in fat and an increase in FFMnew. Because the TOBEC signal is unaffected by bone mineralization, FFMT may provide a more accurate estimation of body composition than do FFMd or FFMdw in this group of individuals.

Aged↗

PubMed2003

Body composition in patients with inflammatory bowel disease: a population-based study.

OBJECTIVE: Weight loss and nutritional depletion are common features of inflammatory bowel disease. Our aim was to assess body composition in patients with Crohn's disease (CD) and ulcerative colitis (UC) and to evaluate possible differences between the patient groups and healthy subjects. METHODS: A total of 60 patients with CD, 60 patients with UC, and 60 healthy subjects were investigated. Each group consisted of 24 men and 36 women. Body composition was measured by dual x-ray absorptiometry and Z scores were obtained by comparison to age- and sex-matched normal values. RESULTS: Bone mineral content and lean body mass were significantly lower in patients with CD compared with patients with UC and healthy subjects. The body composition of CD men was more strongly affected than that of women. UC patients had significantly higher fat mass and body mass index than patients with CD and healthy subjects. There was no difference in the percentage of fat mass between the two patient groups. Corticosteroid treatment and smoking had a negative impact on bone mineral content and lean body mass in CD patients independently of each other. CONCLUSIONS: CD was associated with disturbances in body composition: both bone mineral content and lean body mass were significantly reduced, especially in men with CD. Corticosteroid therapy and smoking had a significant influence on body composition in patients with CD. When studying the effects of inflammatory bowel disease on body composition and nutritional status, patients with CD and UC should be evaluated separately.

Absorptiometry, Photon↗

PubMed1980

An inexpensive method of determining body composition by underwater weighing.

A simple inexpensive densiometric method of determining body composition was compared to a more sophisticated one. Body density (Db), lean body mass (LBM), and relative fat content (%fat) were determined for 16 volunteers, 9 men and 7 women using a simple T-bar apparatus suspended in a swimming pool, and an electronic apparatus in conjunction with a metal tank. Residual volumes (RV) used in the determinations were estimated from age and height (RV-1), held constant at 1,300 ml for men and 1.000 ml for women (RV-2), and measured by the nitrogen washout method (RV-3). No significant difference was observed between the two methods of weighing, although significant differences did exist among the RV techniques. It was concluded that a simplified method of determining body composition is acceptable for screening purposes, but long term studies might require more sophisticated techniques with RV measured at the time of weighing.

Adipose Tissue↗

PubMed1996

Body composition and energy expenditure in thyroidectomized patients during short-term hypothyroidism and thyrotropin-suppressive thyroxine therapy.

Thyroid hormone levels are a major determinant of energy balance and are thought to modify body composition by their effects on metabolism of lipids, carbohydrate and protein. The present study evaluates changes of body composition and basal energy expenditure (BEE) in thyroidectomized patients studied during short-term profound hypothyroidism while off all thyroid hormone before diagnostic whole-body (131)I-imaging and while on thyrotropin-suppressive thyroxine therapy. Basal energy expenditure was assessed by indirect calorimetry, and four-point body impedance analysis was used to estimate body composition. Patients were compared with healthy controls matched with respect to sex, age, height and weight. Compared to healthy controls the percentages of body water and body cell mass were significantly lower while the percentage of fat was significantly higher in patients during short-term hypothyroidism. Weight did not change significantly when patients were put on thyroxine treatment, but body fat (-0.95 +/- 2.25 kg, p < 0.01) decreased while body water (+0.94 +/- 1.31 kg, p < 0.01) and body cell mass (+0.9 +/- 2.5 kg, p < 0.05) increased. With thyroxine replacement, body composition was not significantly different between patients and controls. Compared to healthy controls, BEE was significantly lower in patients without thyroxine replacement (5265 +/- 766 kJ/24h vs 6362 +/- 992 kJ/24h; p < 0.001). With thyroxine treatment, BEE increased (6492 +/- 967 kJ/24h) but was not significantly different from the controls (p > 0.05). Neither body composition nor BEE was significantly different in a subgroup of thyroxine-treated patients with free triiodothyronine or thyroxine values above the normal range. In conclusion, both body composition and energy expenditure showed significant changes when patients were deprived of thyroid hormone. However, no evidence of excess metabolic effects of thyroid hormone during thyrotropin-suppressive thyroxine therapy was found.

Adult↗

PubMedDate not supplied

Body composition in asymptomatic HIV-infected men: cross-sectional and prospective assessment.

Data on body composition changes in HIV infected patients is sparse and controversial. The aim of this study was to assess body composition in asymptomatic HIV-infected men with normal body weight in comparison to healthy HIV-negative control men and to investigate possible body composition changes in HIV-positive patients over a 2-year observation period. One hundred eight asymptomatic seropositive men, aged 19-62 years, and 20 healthy sex, age and weight - matched controls were recruited for the cross-sectional part of the study. Fifty-eight of the HIV+ patients were followed up for 2 years. Body weight, BMI, Bone Mineral Content (BMC), body Fat mass (Fat), % Fat, body Lean mass (Lean) and % Lean was recorded for each subject at the beginning and at the end of the follow-up period. The same analysis was repeated separately for arms, trunk and legs. HIV+ men had increased fat mass and reduced lean mass compared to controls (%Fat in HIV+ 24.3, %Fat in controls 19.2, p=0.012; %Lean in HIV+ 72.1, %Lean in controls 77.0, p=0.014). Lean mass was lower in extremities while fat mass was higher in the trunk region in HIV+ in comparison to controls, irrespective of antiretroviral therapy. Longitudinally, patients with higher baseline %Fat (>24.2, median) presented 20% decrease in fat mass while patients with lower baseline %Fat (< or =24.2) showed a smaller, non-significant decrease in fat mass accompanied by a significant decrease (2.52%) in lean mass. Fat loss occurred in all subjects predominantly in the extremities (16.5-36.45% loss), with relative preservation of trunk fat. It is concluded that otherwise asymptomatic HIV+ men exhibit subtle body composition changes involving reduced lean mass and increased central fat mass. The pattern of weight loss over time depends on baseline fat store: patients with adequate fat stores lose predominantly fat while patients with lower baseline fat stores lose both fat and lean mass. In the entire cohort, there is a tendency towards central adiposity, with the majority of fat being lost from the extremities, a picture resembling metabolic x syndrome.

Journal Article↗

PubMed2004

Hydralazine treatment alters body composition in the rabbit model of obesity.

AIMS: While hydralazine is commonly used as monotherapy in animal studies, its potential side effects are seldom acknowledged. Purported side effects occur from sympathetic and renin-angiotensin system activation, and include tachycardia, oedema, and nausea. We hypothesized that these side effects would alter body composition by increasing body water and/or decreasing body fat. METHODS: Female New Zealand White rabbits were divided into lean and obese control and hydralazine-treated groups. Lean rabbits ate a maintenance diet for 12 weeks; obese rabbits ate an ad lib high fat diet. Hydralazine was administered at 6 and 10-14 mg kg(-1) day(-1) for lean and obese hydralazine groups, respectively. Body composition was determined using triplicate 2-3 g samples of whole body homogenate, and analysed using 2 x 2 ANOVA for diet vs. hydralazine effects. RESULTS: Hydralazine-treated animals had lower body fat (15.7 +/- 1.1 and 21.8 +/- 1.0%, respectively) and higher body water (59.8 +/- 0.8 and 55.4 +/- 0.6%, respectively) compared with controls. While obese controls were heavier than obese hydralazine-treated animals (5.12 +/- 0.09 vs. 4.73 +/- 0.11 kg, respectively) and had greater overall feed consumption (13.5 +/- 0.4 vs. 11.8 +/- 0.4 kg, respectively), a subsequent analysis using subsets that did not differ in body weight or feed consumption yielded the same conclusions. Plasma adrenaline and noradrenaline did not differ between control and hydralazine-treated groups. CONCLUSIONS: Use of hydralazine to control blood pressure alters body composition. Direct or indirect effects of hydralazine may impact physiological systems under study. Alterations in adipose tissue may be of particular concern because of its endocrine function.

Adipose Tissue↗

PubMedDate not supplied

Methods for measuring body composition in newborns--a comparative analysis.

The complexity of nutritional support in infants now makes it necessary to use body-composition methods for accurate nutritional assessment. For this goal a variety of methods of determining body composition have been introduced in research on human nutrition. The purpose of this paper is to review the background and to describe the precision of established techniques, focusing on the results obtained in newborns and infants. The ideal method for assessing newborns' and infants' body composition should be non-invasive, reproducible, accurate, and also relatively inexpensive. In addition, we summarize in this paper data on body composition obtained in normal and pathological newborns by using dual X-ray absorptiometry, one of the reference techniques.

Absorptiometry, Photon↗

PubMed1992

Comparison of four methods to assess body composition in black and white athletes.

Four methods of assessing body composition were compared in 55 black and 35 white, Division I, American football players. Percent body fat (%BF) was estimated with hydrostatic weighing at residual volume, corrected for race; seven-site skinfolds (7 SF), corrected for race; bioelectrical impedance analysis (BIA); and near-infrared spectrophotometry (NIR). Percent body fat with HW in blacks (mean = 14.7%) and whites (19.7%) did not differ (P > .05) from %BF with 7 SF (blacks, 14.7%; whites, 19.0%). In relation to HW, BIA significantly (P < .05) overpredicted (blacks: 20.1%, SEE = 3.2%; whites: 22.3%, SEE = 4.3%) and NIR underpredicted %BF (blacks: 12.6%, SEE = 3.9%; whites: 17.7%, SEE = 3.6%). The contribution of BIA variables (resistance, phase angle, conductance) and NIR optical density to predict %BF was trivial compared to body mass index. It appears that race may not substantially influence %BF prediction by NIR and BIA. It was concluded that when considering the cost and expertise required with NIR and BIA, SF measurements appear to be a superior alternative for rapid and accurate body composition assessment of athletes, independent of race.

Adolescent↗

PubMed1998

Body composition in prepubertal children with human immunodeficiency virus type 1 infection.

OBJECTIVE: To characterize the body composition of human immunodeficiency virus (HIV)-infected children, especially those with growth failure (GF), using laboratory-based methods. DESIGN: A cross-sectional study of body composition measurements. SETTING: Urban, hospital-based body composition laboratory. PARTICIPANTS: Thirty-four prepubertal children with HIV infection, aged 4 to 11 years, recruited from a pediatric HIV clinic. Eighteen HIV-infected children with GF, 16 HIV-infected children with normal rates of growth, and 52 healthy children were studied. MAIN OUTCOME MEASUREMENTS: Anthropometrics, body cell mass (BCM) by total body potassium counting, body fat percent, fat mass, and fat-free mass (FFM) by dual-energy x-ray absorptiometry were determined. RESULTS: Both groups of boys with HIV infection had significantly lower FFM/height ratios compared with healthy boys. The mean BCM/height ratio was also lower in HIV-infected boys with GF compared with healthy boys. Measures of fat of the HIV-infected boys with GF did not differ from healthy controls, but a statistical trend suggesting decreased body fat percent and fat mass/height ratio was observed in HIV-infected boys without GF (P=.06 and .07, respectively). Mean height-for-age, weight-for-age, and weight-for-height percentiles were significantly decreased in HIV-infected boys regardless of growth status as compared with healthy boys. The mean FFM/ height and BCM/height ratios were decreased in HIV-infected girls with GF compared with healthy girls. Body fat percentage and fat mass/height ratio did not differ among the 3 groups of girls. The mean weight-for-height percentiles were not different among the 3 groups of girls. The HIV-infected girls with GF had significantly lower mean height-for-age and weight-for-age percentiles than HIV-infected girls without GF and healthy girls. The mean height-for-age percentiles of the HIV-infected girls with GF did not differ from the healthy girls. CONCLUSIONS: Boys and girls with HIV-associated GF had diminished FFM and BCM. The decrease in FFM and BCM was in striking contrast to the fat compartment, which was normal. Decreased FFM was also detected in boys with HIV infection and normal growth but not in girls with HIV infection and normal growth, suggesting that HIV infection may affect boys differently than girls. The preferential decrease in FFM and BCM over fat observed in these children is similar to findings reported in adults with acquired immunodeficiency syndrome wasting.

Anthropometry↗

PubMed2000

Leptin levels in relation to body composition and insulin concentration in patients with endogenous Cushing's syndrome compared to controls matched for body mass index.

Cushing's syndrome (CS) is associated with weight gain and visceral obesity. We examined the relationship between regional fat distribution and serum levels of leptin, cortisol and insulin. Twenty-three consecutive patients with recently diagnosed CS (18 with pituitary adenoma, 5 with adrenal tumor), where compared to obese controls, matched for age, sex and Body Mass Index (BMI). Serum insulin, leptin, cortisol, C-peptide and body composition determined by DEXA were measured. Serum leptin levels were significantly increased in patients with CS (36.9+/-3.8 vs 18.9+/-2.4 ng/ml, p<0.001; women: 40.1+/-4.6 vs 21.7+/-2.9 ng/ml, p<0.01; men: 27.9+/-5.7 vs 10.9+/-2.3 ng/ml; p<0.05), the same were fasting insulin levels (178+/-30 vs 81+/-10 pmol/l; p<0.01) and C-peptide (1.51+/-0.12 vs 0.77+/-0.07 nmol/l; p<0.001). In a subgroup of 12 patients, truncal fat mass was significantly elevated when compared to obese controls (19.2 kg vs 14.7 kg, p<0.01, and 42% vs 36% in percentage of truncal body tissue, p<0.05), whereas total fat mass was insignificantly increased. Serum leptin correlated positively to total body fat (%) as in patients with CS (r=0.94, p<0.001) as in controls (r=0.68, p<0.01). The correlation to truncal body fat (%) was also significant in both groups (CS: r=0.84, p<0.001; controls: r=0.63, p<0.01). Multiple regression showed that percent total body fat was the predictor of leptin concentrations among patients with CS (r2=0.88, p<0.001) whereas insulin did not contribute significantly to the variance in leptin concentrations. In controls, both leptin and insulin (r2=0.65, p<0.001) contributed significantly to the variations in leptin levels. Controlled for the differences in total body fat, patients with endogenous CS have significantly increased serum leptin levels, compared to BMI-matched obese controls. This suggests that hyperleptinemia in CS not primarily reflects changes in body composition, but is the result of different hormonal influences on adipose tissue.

Adipose Tissue↗

PubMed1975

Activity of some enzymes of energy metabolism in striated muscle of obese subjects with respect to body composition.

The effect of obesity on the activity of some enzymes of energy supplying metabolism was studied in male and female groups of different body weight, using tissue samples of m. quadriceps femoris obtained by a biopsy needle. Both obese males and females displayed a distinct tendency towards anaerobic metabolism (high lactate dehydrogenase activities). The assumption that cytoplasm has an increased capacity in the muscle of the obese for reduction syntheses is supported by the increased ratio of malate dehydrogenase to citrate synthase activities. Compared with controls, less activity of enzymes associated with fatty acid and glucose degradation (hexokinase, hydroxyacyl-CoA dehydrogenase, citrate synthase) was observed in obese males. In obese females the latter enzyme activities did not differ from those in the controls; however, lactate dehydrogenase and triosophosphate dehydrogenase activities were significantly higher. Significant inverse correlations between hexokinase and hydroxyacyl- CoA dehydrogenase activities, on the one hand, and indicators of body composition and body weight, on the other, were found in males. The female group did not display analogous significant relations between the enzymatic organization and indicators of body composition.

Alcohol Oxidoreductases↗

PubMedDate not supplied

Sustained benefits of growth hormone on body composition, fat utilization, physical strength and agility, and growth in Prader-Willi syndrome are dose-dependent.

BACKGROUND: Obesity and hypotonia in children with Prader-Willi syndrome (PWS) are accompanied by abnormal body composition resembling a growth hormone (GH) deficient state. Hypothalamic dysfunction in PWS includes decreased GH secretion, suggesting a possible therapeutic role for GH treatment. While recent studies have demonstrated short-term benefits of treatment with GH, a critical question is whether beneficial changes persist or wane with prolonged therapy, and whether these effects on body composition are dose-dependent as seen in adult GH deficiency. OBJECTIVES AND METHODS: After 24 months of GH theapy at a dose of 1 mg/m2/day ("standard dose"), the effects of 12 additional months of GH treatment at varying doses (0.3-1.5 mg/m2/day) on growth, body composition, strength and agility, pulmonary function, resting energy expenditure (REE), and fat utilization were assessed in 46 children with PWS. Percent body fat, lean muscle mass, and bone mineral density (BMD) were measured by dual X-ray absorptiometry (DXA). Indirect calorimetry was used to determine REE and to calculate respiratory quotient (RQ). RESULTS: During months 24-36 of GH therapy, further changes in body composition (decrease in fat mass, and increase in lean body mass), growth velocity, and REE occurred with standard and higher-dose GH therapy (1.5 mg/m2/day), but not with lower dose GH (0.3 mg/m2/day). Prior improvements in BMD, and strength and agility, which occurred during the initial 24 months, were sustained during the additional 12 months (to 36 months) regardless of dose. CONCLUSIONS: Salutary and sustained GH-induced changes in growth, body composition, and physical function in children with PWS require GH doses of >0.3 mg/m2/day. Conversely, BMD increased during the additional 12 months of therapy regardless of GH dose. Lower doses of GH, effective in improving body composition in adults with GHD, do not appear to be effective in children with PWS.

Absorptiometry, Photon↗