Original Article Anorexia Nervosa: Slow Regain of Bone Mass A ˚ . Valla 1 , I. L. Groenning 1 , U. Syversen 1 and A. Hoeiseth 2 1 The Medical Faculty, University of Trondheim, and 2 Sentrum Roentgen Institute, Oslo, Norway Abstract. In a retrospective study of women aged 18–30 years, aimed at assessing factors associated with peak bone mass (PBM), 13 of 239 study cases reported having had anorexia nervosa. The mean total femoral and lumbar bone mineral density (BMD) values were not significantly lower in women who had had anorexia than in the pooled group (mean Z-scores of –0.60 and –0.48). Cases with less than 6 years since the anorexia had on average a present weight 5.7 kg less than their pre- morbid weights, while cases with more than 6 years since the eating disorder had an average weight 22.5 kg above their pre-morbid weights. The cases who had not regained their weight had BMD values significantly lower than the pooled material (mean Z-scores –1.15 and –0.9 in the lumbar spine and total femur respectively). Those who had regained their weight had BMD values as predicted from their present anthropometric data, while those who had not regained their weight had BMD values that were substantially below that predicted from their present weight. Anorexia nervosa seems to be associated with a low BMD which is even lower than that which can be predicted from the weight loss alone. This suggests that weight loss and other factors, such as menstrual dysfunction and estrogen deficiency, are independent and thus additive causes of bone loss in anorexia nervosa. Recovery of BMD seems slow, but the BMD may become as predicted from the anthropometric data after restoration of body weight and menses. The potential for recovery of BMD seems intact for several years after menarche. Keywords: Anorexia nervosa; Bone mineral density (BMD); Regain of bone mass Introduction Peak bone mass (PBM) is considered a key to osteoporosis. It is therefore essential to understand the factors leading to a low PBM. Eating disorders are reported to have a negative impact on bone, and especially anorexia nervosa is consistently associated with a low bone mass. This may have the consequence that a woman who has had an eating disorder at an early age may suffer a permanent reduction of her PBM. However, some studies have indicated that bone loss in relation to such disorders may be reversible once the patient resumes normal weight and menstrual cycles [1– 3]; others conclude that the reductions appear not to be rapidly reversed [4]. We performed a cross-sectional study of factors affecting PBM in young women. This paper focuses on a subgroup who reported having had anorexia nervosa, with particular attention to the reversibility of bone loss and to factors causing bone loss. Material and Methods The study included 239 women, age range 18–30 years (mean 22.7 years), attending medical school at the universities of Oslo or Trondheim, and nursing students in Trondheim. The study was designed to include as many cases as possible with a variety of factors in order to assess the associations of these with the PBM. The study was not designed to describe a normal population. There were no medical inclusion or exclusion criteria. Upper age limit was set at 30 years. For reasons of anonymity the nonresponders among the students were not recorded, and since the design of the study did not presuppose a normal population, this was not considered mandatory. Osteoporos Int (2000) 11:141–145 ß 2000 International Osteoporosis Foundation and National Osteoporosis Foundation Osteoporosis International Correspondence and offprint requests to: A. Hoeiseth, MD, Sentrum Roentgen Institute, Storgt. 8, 0155 Oslo, Norway. Tel: +47 23 35 56 50. Fax: +47 23 35 56 20. e-mail: ahoiseth@sri.no