The study aimed to assess protein accretion during weight gain in adolescent patients with Anorexia nervosa

Background: Bone health and growth during adolescence require adequate Total Body Protein (TBPr). Re-nutrition for patients with anorexia nervosa (AN) should aim to normalize body composition, i.e. recovery of fat mass and TBPr.

Objective: The study intended to analyze predictors of protein status, including exercise status, in adolescents with AN, and to investigate whether weight gain would replete body protein deficits.

Methods: The investigators assessed TBPr in a longitudinal, observational study as height-adjusted nitrogen index (NI) using in-vivo neutron activation analysis in adolescents with AN at the commencement of refeeding (T0), as well as seven months thereafter (T1), and in age-matched normal weight controls. Lean tissue and fat mass were assessed with Dual-Energy X-Ray Absorptiometry (DXA). BMI, BMI-SDS and lean tissue mass were tested as predictors of protein status using Receiver Operating Characteristic (ROC) analysis.

Patient Inclusion Criteria:

• diagnosis of anorexia nervosa (DSM-IV)
• aged 12 - 19 years
• female gender

Patient Exclusion Criteria:

- existence of a further disease with effect on body composition

Controls:

• no known disease
• normal weight

At baseline assessment, ten patients had primary amenorrhea and 87 girls secondary amenorrhea. Six girls were not amenorrhoeic but were taking oral contraceptives or had lost more than 20% of their weight and fulfilled the remaining diagnostic criteria for AN. The mean duration of the eating disorder at the time of testing was 15 ± 12 months, ranging from 3 to 60 months and estimated premorbid BMI of the AN patients was 20.4 ± 2.9 (13.5 - 28.7 kg/m2; data available for 98 patients). Before admission, the patients (n = 97) had lost 15 ± 7 (2 - 36) kg. The mean weight on hospital admission (data available for 88 patients; 10 patients were outpatients; missing data, n = 5) was 41.1 ± 6.1 kg.