Anorexia Nervosa: Disordered Feedback Regulation in the Growth Hormone-Insulin-Like Growth Factor I Axis

Anorexia nervosa (AN) is a serious eating disorder characterized by self-starvation and extreme weight loss, resulting in a body mass index (BMI) of less than 17.5 kg/m2 (American Psychiatric Association [APA], 2000; Dartmouth College Health Services [DCHS], 1999; Eating Disorders Awareness and Prevention [EDAP], Inc., 2000; Stoving et al, 1999). The psychological disturbances behind the disorder include a refusal to maintain an appropriate weight for the height, age, body type, and activity level of the individual. Patients also suffer from an unreasonable fear of being fat, an obsession with body weight and image, and a constant preoccupation with food and weight (APA, 2000; EDAP, 2000). These features lead to self-denial of nourishment, compulsive exercise, low self-esteem, and withdrawal from friends and family (APA, 2000; DCHS, 1999; EDAP, 2000). Other health consequences develop as well, such as amenorrhea in women, digestive problems, hair loss, sensitivity to cold, slow heart rate, low blood pressure, decreased bone density, muscle loss, and dehydration (DCHS, 1999; EDAP, 2000). Approximately 90-95% of the people suffering from AN are female (EDAP, 2000). In the United States, 1-2% of girls and women are afflicted with the disease (EDAP, 2000). AN is the most common psychological disorder in adolescent girls and has one of the top death rates of any mental disorder (Stoving et al., 1999; EDAP, 2000). Several studies have been performed on the endocrine responses in AN. A deeply investigated area is the elevated basal and pulsatile secretory levels of growth hormone (GH) in individuals with AN. The release of GH from the pituitary is mediated by the secretion of growth hormone releasing hormone (GHRH) and somatostatin from the hypothalamus: GHRH Anorexia Nervosa: Disordered Feedback Regulation in the Growth Hormone-Insulin-Like Growth Factor I Axis