Increase in weight and BMI does not lead to bone mass recovery in adolescents with anorexia nervosa.

MB OLIVERI; MS PARISI; L DEL RÍO

Phoenix

Congreso; XXIII Congreso Anual de la ASBMR; 2001

American Society for Bone and Mineral Research

Osteopenia and osteoporosis are established complications of anorexia nervosa.However, whether the diminution in the bone mass of adolescent patients (before theyreach their peak bone mass) can be recovered partly or completely and the factors thatdetermine recovery have not been clearly established to date.A total of 113 young female patients diagnosed with anorexia nervosa were studied.Bone mineral density of the lumbar spine (LS BMD) was determined by DEXA(LUNAR DPX-L ) at baseline. Follow-up determinations were performed at one year in38 patients, and at 3 years in 21. The Z score of LS BMD (ZLS) was calculated bycomparing to a control population of 393 women aged 11 to 19 years. Baselineevaluation: age (Mean ± SD): 15.9 ± 2.1 years (range: 11-19), BMI; 16.1 ± 1.8;diminution in body weight according to age (dw/a): 21.0, LS BMD 0.999 ± 0.153g/cm2; ZLS: -1.2. ZLS and LS BMD correlated positively with BMI: r= 0.21and 0.29(p<0.05) and with weight: r= 0.32 and 0.44 (p<0.01) respectively (Spearman rankcoefficients). The population was divided in groups according to age (table 1)Results at 12 months showed an average 12% increase in weight from 40 to 44.8 kg(p<0.001), an increase in BMI from 16.6 to 17 9 (p<0.001); dw/a improved from -19.3to –13.3% (p<0.01), whereas LS BMD (g/cm2) remained unchanged: 1.004 ± 0.143 to1.004 ± 0.118 g/cm2. At 36 months follow-up, results showed an average increase inweight from 38.2 to 44.5 kg (16%) (p<0.01) and in BMI from 15.8 to 17.9 (p<0.001);dw/a improved from -23.6 at baseline to –15.7 (p<0.01) but no improvement LS BMDwas observed: 0.951 ± 0.145 to 0.957 ± 0.132 g/cm2 (Wilcoxon signed ranks test).Conclusions: 1) Baseline evaluation revealed decreased LS BMD values, which werelowest in the 11-13 years group, associated with a significant diminution in BMI andweight; 2) In spite of the significant improvement in weight and BMI at 1 and 3 yearsfollow-up, LS BMD did not recover. This finding coupled with the weak correlationbetween BMI, weight, and LS BMD observed at baseline would seem to indicate thatweight loss and recovery only partly influences bone mass loss and recovery. thatweight loss and recovery does not play a significant role in bone mass loss andrecovery.Table 1: ** p<0.001compared to B and C * p<0.02 compared to B (Mann-Whitney Test)Age N dw/a BMI ZLS11-13 16 24.0±10 14.3** -1.7±1.8*14-16 52 20.6±8 16.3 -1.0±1.217-19 45 20.5±10 16.6 -1.26±1.5