Safety Profile of Insulin Like Growth Factor-1 (IGF-I) Administration in Adolescents

The purpose of this study was to determine whether giving insulin like growth factor-I (IGF-I) to adolescent low weight girls is safe and whether this increases levels of bone formation markers.

Adolescents with anorexia nervosa (AN) are at high risk for low bone mineral density at a time when healthy adolescents are rapidly accruing bone, with implications for peak bone mass and fracture risk in later life. They are also deficient in insulin-like growth factor I (IGF-I), the bone trophic factor made in the liver in response to growth hormone (GH), despite elevated levels GH. It is possible that deficiency of IGF-I, a hormone very important for the maintenance of skeletal integrity, may contribute to the severe osteopenia seen in AN. The physiologic effects of rhIGF-I treatment in adolescents with AN had not been studied. The goal of this proposal was to investigate the acute effects of rhIGF-I on bone metabolism in adolescent girls with AN.

Specific Aim: It was hypothesized that adolescent AN patients, being IGF-I deficient, would respond to exogenously administered rhIGF-I with elevations in biochemical indices of bone turnover. Therefore, rhIGF-I was administered to AN patients by subcutaneous injection over 10 days with concomitant measurement of indices of bone turnover, and calcium regulatory hormones.

Inclusion Criteria:

• Adolescent girls with anorexia nervosa 12-18 years old

Exclusion Criteria:

• Pregnancy or nursing
• Hematocrit < 30%, K < 3 mmol/L
• Any illness (other than anorexia nervosa) known to affect bone and mineral metabolism such as diabetes, alcoholism, untreated hypo- or hyperthyroidism, or hyperparathyroidism
• History of use of any medicine, such as corticosteroids, known to affect bone density. Subjects who were on estrogen were still eligible to participate in the study.