What Causes UC?
Barbara wrote into the blog this week regarding her diagnosis of ulcerative proctitis/colitis and queried what causes colorectal inflammation in UC:
"I had a routine colonoscopy in Sept of 2006 and all of just fine....I never had problems in that area.....in May of 2007 I was struck with a terrible intestinal virus which caused me to vomit and have diarrhea at the same time for 5 days....it was the worst illness I have ever had....when it was over I started to bleed from the rectum with my bowel movements and shortly afterwards I was given a sigmoidoscopy and it was determined through biopsies that I had UC of the rectum or Proctitis....I am still in shock with this diagnosis since I never had a problem in this area.....what could have caused this to happen to me?"
Barbara's story of feeling completely fine and even having a normal colonoscopy prior to the onset of UC is not uncommon. The onset of UC is most often abrupt and seems to occur out of the blue. Barbara's question about why this happened to her is one of the most frequently asked questions by patients. While an exact cause for UC is not known, current theory suggests that it is likely due to a combination of genetics and environmental triggers. When a genetically predisposed individual comes in contact with a causal environmental agent, he/she may develop an inflammatory state that results in colitis. There is a lot of ongoing research regarding the genetics of IBD and what the potential environmental triggers could be.
At the present time, the search for genes suspected to cause IBD has been more fruitful for Crohn's disease than UC. Advances in new genetic and molecular techniques, however, may help in the identification of genetic markers in UC.
Much research has focused on environmental agents that may be associated with the onset or exacerbation of IBD. Some postulated risk factors for IBD include:
1) Cigarette smoking - protective factor for UC; flares often occur after smoking cessation
2) Prior appendectomy - protective factor for UC, risk factor for Crohn's
3) Antibiotics - may alter bowel flora
4) Oral contraceptives - weak association if any
5) High fat or sugar diet - no conclusive evidence for dietary causes
6) Lack of breastfeeding as an infant
7) Infections (both GI and otherwise)
8) Vaccinations - no conclusive evidence vaccinations cause IBD
9) Alterations in bowel bacteria
Barbara relates that she had a significant gastrointestinal infection which preceded the onset of her UC. Many patients describe such an event which seems to incite an inflammatory cascade that results in UC. As discussed in a previous blog, patients with UC have a predilection for GI infections cause by a bug called C. diff. Thus, in Barbara's case it may be that she possesses a genetic predisposition to IBD and her gastrointestinal infection was the inciting event for her UC.
For more information on the genetics and causes of IBD, please see our blogs from July 17 and 19, 2007 in the archives.