Recovery from Osteopenia in Adolescent Girls with Anorexia Nervosa*

Abstract

Osteopenia is a frequent complication of anorexia nervosa (AN). To determine whether the deficit in bone mineral changes during the course of this illness, we studied 15 adolescent patients prospectively for 12-16 months using dual photon absorptiometry of the spine and whole body. At follow-up, mean weight, height, and body mass index (BMI) had increased significantly, although 6 girls had further weight loss or minimal gain (less than 1.2 kg). Spontaneous menses occurred in 2 girls, and 3 others were given estrogen replacement. Bone mineral density of the lumbar spine did not change significantly (mean +/- SD, 0.836 +/- 0.137 vs. 0.855 +/- 0.096 g/cm2), while whole body bone mineral density increased (0.710 +/- 0.118 vs. 0.773 +/- 0.105; P less than 0.05). Despite gains in bone mineral, 8 patients had osteopenia of the spine and/or whole body. Changes in weight, height, and BMI were significant predictors of change in bone mineral density. Increased bone mass occurred with weight gain before return of menses; conversely, weight loss was associated with further decreases in bone density. In 1 patient who failed to gain weight, estrogen therapy resulted in increased spinal, but not whole body, bone mineral. We also studied a second group of 9 women who had recovered from AN during adolescence. All 9 had normal whole body bone mineral for age, but 3 had osteopenia of the lumbar spine. We conclude that osteopenia in adolescents with AN reflects bone loss, perhaps combined with decreased bone accretion. Weight rehabilitation results in increased bone mineral before the return of menses. Estrogen may have an independent effect on bone mass. The persistence of osteopenia after recovery indicates that deficits in bone mineral acquired during adolescence may not be completely reversible.

Medical complications in adolescents with anorexia nervosa: A review of the literature

“…Weight recovery has been shown to increase whole-body bone density, even before the return of menses. 43 In this same study, however, lumbar bone density remained significantly reduced and subsequent weight loss was associated with further decreases in bone density. Despite their gains in BMD, 8 patients had osteopenia of the spine or whole body, or both.…”

“…40,41 Studies have shown that adolescents with AN have significantly reduced bone mass compared with agematched 41 and bone age-matched controls. 42 In one study, 41 the lumbar bone density of two-thirds of adolescents with AN was more than 2 SD lower than the normal values for their age. Of note, the changes in bone density occurred very early in the course of the illness, with one half of these adolescent girls having had a diagnosis of AN for <1 year.…”

“…In addition, BMD in adolescents with AN has been shown to be significantly correlated with BMI, age at onset, and the duration of illness. 41 The possible mechanisms of low bone mass observed in adolescents with AN are complex. A number of identified factors have been shown to influence the attainment of peak bone mass in adolescents with AN: hypoestrogenemia, decreased levels of IGF-1, increased cortisol levels, physical activity, poor nutrition, low calcium and vitamin D intake, and low body mass.…”

“…Finally, one-third of young women who recovered from AN during adolescence had persistent osteopenia of the lumbar spine. 43 Such persistence suggests that BMD deficits may not be completely reversible.…”

“…Weight restoration is the safest and most effective way to increase bone mineraliztion in adolescents with AN. 43 Changes in body weight and composition (in particular increases in lean body mass), even before the return of menses, is important to bone mineralization. Weight at resumption of menses has been used as a biologic marker of health.…”