Acromegaly is a disease of the pituitary gland that involves overproduction of growth
hormone. Pegvisomant works by blocking binding of GH to receptors found in tissues throughout
the body. Human studies have evaluated pegvisomant action by measuring reduction of IGF-I
levels in the blood. However, no studies have evaluated the effects of blocking GH receptors
in tissues. In this study, we will study tissue biomarkers for pegvisomant action in GH and
IGF-I dependent signaling pathways in colon tissue of patients with acromegaly treated with
pegvisomant.