Subjects will have measurements of growth hormone using an oral glucose tolerance test (OGTT), IGF-I, free IGF-I and levels of IGF binding proteins at four time points after their pituitary surgery: Day 1, Day 42 (6 weeks), Day 84 (12 weeks), and day 365 (1 year). Subjects will also have an MRI of the pituitary done at 12 weeks and 1 year. OGTT and IGF-I are routinely measured to assess whether or not a person is cured of their acromegaly. An MRI of the pituitary is routinely done at 12 weeks and 1 year after surgery to assess the results of surgery. Free IGF-I and IGF binding proteins are not routinely measured after surgery, but are being done to see if they relate more strongly to disease activity than IGF-I and growth hormone.