Rasha T Hamza and Doaa H Hewedi
Objective: Puberty is associated with marked changes in body weight and hormonal profile related to pubertal stage such as insulin-like growth factor 1 (IGF-1). These changes are also associated with Anorexia Nervosa (AN) and may impact bone. Thus our study aimed to study bone metabolism and possible etiology of osteopenia in Egyptian adolescent AN girls.
Method: Twenty five adolescent girls were studied compared to 30 healthy age - and pubertal stage- matched controls. All participants were subjected to clinical evaluation, neuropsychiatric assessment, auxological measurements, bone age assessment, bone density and body composition assessment; and measurement of serum growth hormone (GH), IGF-1, ionized calcium, phosphorus, 25 hydroxy vitamin D [25-(OH)D] and serum osteocalcin (OC).
Results: Lean body mass and Bone Mineral Density (BMD) were significantly reduced in AN patients compared with controls even when controlled for height. Serum GH was elevated significantly in patients (P=0.02). Serum IGF-1 level was reduced significantly in AN (P=0.0001). Serum ionized calcium, vitamin D and OC levels were significantly lower in patients (P=0.03, 0.04 and 0.02 respectively). IGF-1 was strongly positively correlated with OC in patients (r=0.865; P=0.001). In stepwise regression analysis, IGF-1 caused 73% (r2=0.75; P=0.001) of variation in OC levels in AN.
Discussion: This study describes low bone formation in AN compared with age - and pubertal stage-matched adolescents. Serum levels of IGF-1 are highly correlated with bone formation and thus, IGF-1 measurement can be used as a marker for bone osteoblastic activity in AN.