Verena Haas1, Dorothea Kent2, Michael R Kohn3, Sloane Madden4, Simon Clarke3, Julie Briody5, Felix Fischer6, Manfred J Müller7, Kevin Gaskin2. 1. Department of Child and Adolescent Psychiatry, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany. 2. James Fairfax Institute of Pediatric Nutrition, Department of Adolescent and Young Adult Medicine, Westmead Hospital and Centre for Research into Adolescents' Health, and Departments of Psychological and Nuclear Medicine, The Children's Hospital at Westmead, Sydney, Australia. 3. Department of Adolescent and Young Adult Medicine, Westmead Hospital and Centre for Research into Adolescents' Health, and Departments of Psychological and Nuclear Medicine, The Children's Hospital at Westmead, Sydney, Australia. 4. Psychological and Nuclear Medicine, The Children's Hospital at Westmead, Sydney, Australia. 5. Nuclear Medicine, The Children's Hospital at Westmead, Sydney, Australia. 6. Department of Psychosomatic Medicine, Center for Internal Medicine and Dermatology, Charité-Universitätsmedizin Berlin, Germany. 7. Institut für Humanernährung und Lebensmittelkunde, Christian-Albrechts-Universität zu Kiel, Germany.
Abstract
Background: Bone health and growth during adolescence require adequate total body protein (TBPr). Renutrition for patients with anorexia nervosa (AN) should aim to normalize body composition and to recover both fat mass and TBPr. Objective: We intended to analyze predictors of protein status, including exercise status, in adolescents with AN and to investigate whether weight gain would replenish body protein deficits. Methods: We assessed TBPr in a longitudinal, observational study as height-adjusted nitrogen index (NI) using in vivo neutron activation analysis in 103 adolescents with AN [mean ± SD age, 15.6 ± 1.4 y; body mass index (BMI, in kg/m2), 16.5 ± 1.6] at the commencement of inpatient refeeding (T0), in 56 of these patients 7 mo thereafter as outpatients (T1), and in age-matched controls (C; n = 51, 15.5 ± 2.1 y, BMI 20.7 ± 1.9). Lean tissue and fat mass were assessed by dual-energy X-ray absorptiometry. BMI, BMI standard deviation score, and lean tissue mass were tested as predictors of protein status using receiver operating characteristic analysis. Results: At T0, NI was decreased in AN (AN, 0.88 ± 0.10 compared with C, 1.00 ± 0.08, P < 0.001). In 34%, the patients showed protein depletion. Patients classified as ``exercisers'' had a higher NI than did ``nonexercisers'' (0.89 ± 0.11 compared with 0.85 ± 0.08, P = 0.045). BMI, BMI standard deviation score, and lean tissue mass did not show potential as predictors of protein status. Despite increases in weight (+6.9 ± 4.5 kg), and BMI (+2.5 ± 1.7), protein status did not improve (TBPr T0, 8.0 ± 1.1 kg; T1, 8.1 ± 1.0 kg, P = 0.495). In an AN subgroup at 7 mo matched with controls in age (AN, 16.5 ± 1.1 y; C, 16.2 ± 1.8 y) and BMI (AN, 20.5 ± 1.4; C, 20.7 ± 1.3), protein status was still not normalized in AN (NI: AN, 0.89 ± 0.09 compared with C, 1.00 ± 0.07, P < 0.001). Conclusions: Adolescents recovering from AN remained protein depleted at 7 mo after baseline assessment, even though they were weight restored.
Background: Bone health and growth during adolescence require adequate total body protein (TBPr). Renutrition for patients with anorexia nervosa (AN) should aim to normalize body composition and to recover both fat mass and TBPr. Objective: We intended to analyze predictors of protein status, including exercise status, in adolescents with AN and to investigate whether weight gain would replenish body protein deficits. Methods: We assessed TBPr in a longitudinal, observational study as height-adjusted nitrogen index (NI) using in vivo neutron activation analysis in 103 adolescents with AN [mean ± SD age, 15.6 ± 1.4 y; body mass index (BMI, in kg/m2), 16.5 ± 1.6] at the commencement of inpatient refeeding (T0), in 56 of these patients 7 mo thereafter as outpatients (T1), and in age-matched controls (C; n = 51, 15.5 ± 2.1 y, BMI 20.7 ± 1.9). Lean tissue and fat mass were assessed by dual-energy X-ray absorptiometry. BMI, BMI standard deviation score, and lean tissue mass were tested as predictors of protein status using receiver operating characteristic analysis. Results: At T0, NI was decreased in AN (AN, 0.88 ± 0.10 compared with C, 1.00 ± 0.08, P < 0.001). In 34%, the patients showed protein depletion. Patients classified as ``exercisers'' had a higher NI than did ``nonexercisers'' (0.89 ± 0.11 compared with 0.85 ± 0.08, P = 0.045). BMI, BMI standard deviation score, and lean tissue mass did not show potential as predictors of protein status. Despite increases in weight (+6.9 ± 4.5 kg), and BMI (+2.5 ± 1.7), protein status did not improve (TBPr T0, 8.0 ± 1.1 kg; T1, 8.1 ± 1.0 kg, P = 0.495). In an AN subgroup at 7 mo matched with controls in age (AN, 16.5 ± 1.1 y; C, 16.2 ± 1.8 y) and BMI (AN, 20.5 ± 1.4; C, 20.7 ± 1.3), protein status was still not normalized in AN (NI: AN, 0.89 ± 0.09 compared with C, 1.00 ± 0.07, P < 0.001). Conclusions: Adolescents recovering from AN remained protein depleted at 7 mo after baseline assessment, even though they were weight restored.