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Zürich, Switzerland

Birzniece V.,Garvan Institute of Medical Research | Birzniece V.,University of Sydney | Birzniece V.,University of Western Sydney | Khaw C.-H.,Garvan Institute of Medical Research | And 6 more authors.
European Journal of Endocrinology | Year: 2015

Objective: To compare estimates by bioimpedance spectroscopy analysis (BIS) of extracellular water (ECW), fat mass (FM), and fat-free mass (FFM) against standard techniques of bromide dilution and dual energy X-ray absorptiometry (DXA) during intervention that causes significant changes in water compartments and body composition.Methods: Body composition analysis using BIS, bromide dilution, and DXA was performed in 71 healthy recreational athletes (43 men, 28 women; aged 18-40 years; BMI 24±0.4 kg/m2) who participated in a double-blinded, randomized, placebo-controlled study of GH and testosterone treatment. The comparison of BIS with bromide dilution and DXA was analyzed using linear regression and the Bland-Altman method.Results: At baseline, there was a significant correlation between BIS and bromide dilution-derived estimates for ECW, and DXA for FM and FFM (P<0.001). ECW by BIS was 3.5G8.1% lower compared with bromide dilution, while FM was 22.4±26.8% lower and FFM 13.7±7.5% higher compared with DXA (P<0.01). During treatment, the change in ECW was similar between BIS and bromide dilution, whereas BIS gave a significantly greater reduction in FM (19.4±44.8%) and a greater increase in FFM (5.6±3.0%) compared with DXA (P<0.01). Significant differences in body composition estimates between the BIS and DXA were observed only in men, particularly during the treatment that caused greatest change in water compartments and body composition.Conclusion: In healthy adults, bioimpedance spectroscopy is an acceptable tool for measuring ECW; however, BIS overestimates FFM and substantially underestimates FM compared with DXA. © 2015 European Society of Endocrinology Printed in Great Britain. Source

Meinhardt U.,Center for Pediatric Endocrinology | Nelson A.E.,Garvan Institute of Medical Research | Hansen J.L.,Garvan Institute of Medical Research | Birzniece V.,Garvan Institute of Medical Research | And 4 more authors.
Annals of Internal Medicine | Year: 2010

Background: Growth hormone is widely abused by athletes, frequently with androgenic steroids. Its effects on performance are unclear. Objective: To determine the effect of growth hormone alone or with testosterone on body composition and measures of performance. Design: Randomized, placebo-controlled, blinded study of 8 weeks of treatment followed by a 6-week washout period. Randomization was computer-generated with concealed allocation. (Australian-New Zealand Clinical Trials Registry registration number: ACTRN012605000508673) Setting: Clinical research facility in Sydney, Australia. Participants: 96 recreationally trained athletes (63 men and 33 women) with a mean age of 27.9 years (SD, 5.7). Intervention: Men were randomly assigned to receive placebo, growth hormone (2 mg/d subcutaneously), testosterone (250 mg/wk intramuscularly), or combined treatments. Women were randomly assigned to receive either placebo or growth hormone (2 mg/d). Measurements: Body composition variables (fat mass, lean body mass, extracellular water mass, and body cell mass) and physical performance variables (endurance [maximum oxygen consumption], strength [dead lift], power [jump height], and sprint capacity [Wingate value]). Results: Body cell mass was correlated with all measures of performance at baseline. Growth hormone significantly reduced fat mass, increased lean body mass through an increase in extracellular water, and increased body cell mass in men when coadministered with testosterone. Growth hormone significantly increased sprint capacity, by 0.71 kJ (95% CI, 0.1 to 1.3 kJ; relative increase, 3.9% [CI, 0.0% to 7.7%]) in men and women combined and by 1.7 kJ (CI, 0.5 to 3.0 kJ; relative increase, 8.3% [CI, 3.0% to 13.6%]) when coadministered with testosterone to men; other performance measures did not significantly change. The increase in sprint capacity was not maintained 6 weeks after discontinuation of the drug. Limitations: Growth hormone dosage may have been lower than that used covertly by competitive athletes. The athletic significance of the observed improvements in sprint capacity is unclear, and the study was too small to draw conclusions about safety. Conclusion: Growth hormone supplementation influenced body composition and increased sprint capacity when administered alone and in combination with testosterone. © 2010 American College of Physicians. Source

Huang K.E.,Center for Pediatric Endocrinology | Mittelman S.D.,Center for Pediatric Endocrinology | Mittelman S.D.,Saban Research Institute | Geffner M.E.,Center for Pediatric Endocrinology | And 2 more authors.
Journal of Pediatric Hematology/Oncology | Year: 2015

Advances in chelation therapy and noninvasive monitoring of iron overload have resulted in substantial improvements in the survival of transfusion-dependent patients with thalassemia major. Myocardial decompensation and sepsis remain the major causes of death. Although endocrine abnormalities are a well-recognized problem in these iron-overloaded patients, adrenal insufficiency and its consequences are underappreciated by the hematology community. The aims of this study were to determine the prevalence of adrenal insufficiency in thalassemia major subjects, to identify risk factors for adrenal insufficiency, and to localize the origin of the adrenal insufficiency within the hypothalamic-pituitary-adrenal axis. Eighteen subjects with thalassemia major (18.9±9.3 y old, 7 female) were tested for adrenal insufficiency using a glucagon stimulation test. Those found to have adrenal insufficiency (stimulated cortisol <18 μg/dL) subsequently underwent an ovine corticotropin-releasing hormone (oCRH) stimulation test to define the physiological basis for the adrenal insufficiency. The prevalence of adrenal insufficiency was 61%, with an increased prevalence in males over females (92% vs. 29%, P=0.049). Ten of 11 subjects who failed the glucagon stimulation test subsequently demonstrated normal ACTH and cortisol responses to oCRH, indicating a possible hypothalamic origin to their adrenal insufficiency. Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved. Source

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