Effect of Transdermal Estradiol and Insulin-like Growth Factor-1 on Bone Endpoints of Young Women with Anorexia Nervosa

Abstract

Context: Anorexia nervosa (AN) is prevalent in adolescent girls and is associated with bone impairment driven by hormonal alterations in nutritional deficiency. Objective: To assess the impact of estrogen replacement with and without recombinant human insulin-like growth factor-1 (rhIGF-1) administration on bone outcomes. Design: Double-blind, randomized, placebo-controlled 12-month longitudinal study. Participants: Seventy-five adolescent and young adult women with AN age 14 to 22 years. Thirty-three participants completed the study. Intervention: Transdermal 17-beta estradiol 0.1 mg/day with (i) 30 mcg/kg/dose of rhIGF-1 administered subcutaneously twice daily (AN-IGF-1+) or (ii) placebo (AN-IGF-1-). The dose of rhIGF-1 was adjusted to maintain levels in the upper half of the normal pubertal range. Main Outcome Measures: Bone turnover markers and bone density, geometry, microarchitecture, and strength estimates. Results: Over 12 months, lumbar areal bone mineral density increased in AN-IGF-1- compared to AN-IGF-1+ (P=0.004). AN-IGF-1+ demonstrated no improvement in areal BMD in the setting of variable compliance to estrogen treatment. Groups did not differ for 12-month changes in bone geometry, microarchitecture, volumetric bone mineral density (vBMD), or strength (and results did not change after controlling for weight changes over 12 months). Both groups had increases in radial cortical area and vBMD, and tibia cortical vBMD over 12 months. Levels of a bone resorption marker decreased in AN-IGF-1- (P=0.042), while parathyroid hormone increased in AN-IGF-1+ (P=0.019). AN-IGF-1- experienced irregular menses more frequently than did AN-IGF-1+, but incidence of all other adverse events did not differ between groups. Conclusions: We found no additive benefit of rhIGF-1 administration for 12 months over transdermal estrogen replacement alone in this cohort of young women with AN.