[Adolescent with anorexia nervosa: consequences on bone mineralization]

Abstract

Introduction: Anorexia nervosa is responsible for abnormalities in bone mineralization, which are well known and described in adults, but less well documented in adolescents. The aim of this research was to evaluate the frequency and severity and to determine predictive factors for these abnormalities in a population of adolescents with diagnosed anorexia nervosa.

Patients and methods: This retrospective study involved 39 female adolescents with anorexia nervosa having undergone dual energy X-ray absorptiometry prior to the age of 18 years. Clinical (age, Tanner puberty stages, weight, body mass index [BMI] at different times during the anorexia phase and amenorrhea features), radiological (bone mineral density [BMD] in Z-score units and in absolute values), and biological (calcemia and vitamin D) parameters were collected.

Results: In total, 20 patients (51%) presented osteopenia (Z-score <-1 DS and >-2.5 DS) and 2 (5%) had osteoporosis (Z-score <-2.5 DS). Five (13%) exhibited a Z-score less than -2 DS. BMD expressed in Z-scores correlated with none of the parameters assessed. At univariate analysis, BMD in absolute values correlated with the age at disease onset, BMI, weight loss at the lowest weight achieved and BMI at the time of densitometry (P<0.01). At multivariate analyses, only the correlation with the age at disease onset persisted (P<0.05).

Conclusion: Bone loss in anorexia nervosa is a complication that may be present as early as adolescence. It must be systematically searched for in all adolescents with severe malnutrition because, even if BMD correlated with nutritional parameters, no clinical predictor for osteoporosis or osteopenia could be identified in this study.