The Effects of Anorexia Nervosa on Bone Metabolism in Female Adolescents1
- 1 December 1999
- journal article
- Published by The Endocrine Society in Journal of Clinical Endocrinology & Metabolism
- Vol. 84 (12), 4489-4496
- https://doi.org/10.1210/jcem.84.12.6207
Abstract
Osteopenia is a frequent, often persistent, complication of anorexia nervosa (AN) in adolescent girls and occurs during a critical time in bone development. Little is known about bone metabolism in this patient population. Therefore, we measured bone density (BMD) and body composition by dual energy x-ray absorptiometry, nutritional status, bone turnover, calcium, and hormonal status in 19 adolescent girls with AN (mean ± sem, 16.0 ± 0.4 yr) and 19 bone age-matched controls. The mean duration of AN was 19 ± 5 months. Spinal (L1–L4) osteopenia was common in AN. Lumbar anterioposterior BMD was more than 1 sd below the mean in 42% of patients, and lateral spine BMD was more than 1 sd below in 63% of patients compared with controls. Lean body mass significantly predicted lumbar bone mineral content (r = 0.75; P < 0.0001) in controls only. In AN, duration of illness was the most significant predictor of spinal BMD (lumbar: r = −0.44; P = 0.06; lateral: r= −0.59; P = 0.008). AN adolescents with mature BA (15 yr and greater) were hypogonadal [estradiol, 16.2 ± 1.9 vs. 23.3 ± 1.6 pg/mL (P = 0.01); free testosterone, 0.70 ± 0.17 vs. 1.36 ± 0.14 pg/mL (P = 0.01)] although dehydroepiandrosterone sulfate and urinary free cortisol levels did not differ. Leptin levels were reduced in AN (2.9 ± 2.1 vs. 16.5 ± 1.8 ng/mL; P < 0.0001). Insulin-like growth factor I (IGF-I) was reduced in AN to 50% of control levels (219 ± 41 vs. 511 ± 35 ng/mL; P < 0.0001) and correlated with all measures of nutritional status, particularly leptin (r = 0.80; P < 0.0001). Surrogate markers of bone formation, serum osteocalcin (OC) and bone-specific alkaline phosphatase (BSAP), were significantly (P = 0.02) reduced in AN vs. controls (OC, 39.1 ± 6.4 vs. 59.2 ± 5.2 ng/mL; BSAP, 27.9 ± 4.0 vs. 40.6 ± 3.4 U/L). The majority of the variation in bone formation in AN was due to IGF-I levels (OC: r2 = 0.72; P = 0.002; BSAP: r2 = 0.53; P = 0.01) in stepwise regression analyses. Bone resorption was comparable in patients and controls. These data demonstrate that bone formation is reduced and uncoupled to bone resorption in mature adolescents with AN in association with low bone density. Lean body mass was a significant predictor of BMD in controls, but not AN patients. The major correlate of bone formation in AN was the nutritionally dependent bone trophic factor, IGF-I. Reduced IGF-I during the critical period of bone mineral accumulation may be an important factor in the development of osteopenia in adolescents with AN.Keywords
This publication has 32 references indexed in Scilit:
- Do Dietary Calcium and Age Explain the Controversy Surrounding the Relationship Between Bone Mineral Density and Vitamin D Receptor Gene Polymorphisms?Journal of Bone and Mineral Research, 1998
- Bone mass and soft tissue composition in adolescents with anorexia nervosaBone, 1996
- Bone mineralization, hypothalamic amenorrhea, and sex steroid therapy in female adolescents and young adultsThe Journal of Pediatrics, 1995
- Disturbances in growth hormone secretion and action in adolescents with anorexia nervosaThe Journal of Pediatrics, 1994
- Biochemical markers of bone turnover in girls during pubertyClinical Endocrinology, 1994
- Predictors of axial and peripheral bone mineral density in healthy children and adolescents, with special attention to the role of pubertyThe Journal of Pediatrics, 1993
- Mineral balance and bone turnover in adolescents with anorexia nervosaThe Journal of Pediatrics, 1993
- Outcome of bone mineral density in anorexia nervosa patients 11.7 years after first admissionJournal of Bone and Mineral Research, 1993
- Serum levels of carboxyterminal propeptide of type I procollagen in healthy children from 1 st year of life to adulthood and in metabolic bone diseasesEuropean Journal of Pediatrics, 1992
- Short stature in anorexia nervosa patientsJournal of Adolescent Health, 1985