Responding to Illini's comment---
IBD Blood results are not dangerous, and are simply guidelines to be used in conjunction with colonoscopies; small bowel follow-through tests (barium swallow) etc. The results of all the tests, including the blood work, assist the doctor in making his or her best judgement in how to treat the disease.
By the way, how a person feels, and how minor or severe a person's physical symptoms are, are a very individual thing and do NOT necessarily determine how severe the disease is. I am extremely fortunate in that I have very few physical symptoms, yet multiple colonoscopies show that my condition is moderately severe.
There are no guarantees in life; so of course no doctor (or blood test) can say for sure whether or not a particular treatment is going to work, or what will definitely happen if treatment is turned down. Once again, though, a good gastroenterologist has accumulated enough experience to give opinions about likely senarios.
Your body is your own, so ultimately you get to make the final decision on what you feel is appropriate for you.
53 year old female;
Have had Crohn's of terminal ileum for 8 yrs, but finally accepted diagnosis when it was confirmed Feb. 2008.
Allergic to Pentasa and Entocort. Will go on 6-MP in a few months.