Predicting Menstrual Recovery in Hospitalized Adolescents with Anorexia Nervosa Using Body Fat Percent Estimated by Bio-Impedance Analysis

איתי טוקטלי לצר ¹ Hila Kidron-Levy ² Daniel Stein ² Adi Enoch Levy ² Galit Yosef ² Tomer Ziv-Baran ⁴ Gal Dubnov-Raz ³

¹Pediatrics A, The Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, Ramat-Gan, Israel, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel, Tel Aviv, Israel
²Pediatric Psychosomatic Department, The Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, Ramat-Gan, Israel, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel, Tel Aviv, Israel
³Exercise, Nutrition and Lifestyle Clinic, The Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, Ramat-Gan, Israel, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel, Tel Aviv, Israel
⁴Department of Epidemiology and Preventive Medicine, School of Public Health, Sackler Faculty of Medicine, Tel Aviv University Tel Aviv, Israel, Tel Aviv, Israel

Objective: To identify the threshold of total body fat percentage (TBF%) required for the resumption of menses (ROM) in hospitalized female adolescents with anorexia nervosa (AN) using bio-impedance analysis (BIA).

Methods: All female adolescents hospitalized with AN in our medical center were evaluated in a longitudinal prospective study during the years of 2012-2017. Anthropometric data, body fat measured by BIA and hormonal determinants were collected periodically, in addition to routine medical and gynecological assessments.

Results: Of the 118 participants examined during the study period, 62 presented with secondary amenorrhea, of which 20 participants remained with amenorrhea and 42 had ROM during hospitalization. At discharge, participants with ROM regained significantly more weight, and had higher mean BMI, BMI SDS, and TBF% than those that remained with amenorrhea. Receiver operating characteristic (ROC) analysis identified that a TBF% of 21.2% had the highest discriminative ability for ROM (sensitivity=88%, specificity=85%, positive predictive value=93%). Compared with the anthropometric parameters, TBF% had the highest area under curve (AUC=0.895), which significantly differed from that of BMI SDS (AUC=0.643, p=0.007) and body weight (AUC=0.678, p=0.03).

Conclusions: BIA is a safe and relatively simple method to assess the TBF% required for the return of balanced menstrual cycles in female adolescents with AN. The TBF% with the highest discriminative ability for menstrual resumption as assessed by BIA is 21.2%.