IBD vs IBS

While learning more about the exciting world of Inflammatory Bowel Disease, I learned that Inflammatory Bowel Disease (IBD) and Irritable Bowel Syndrome (IBS) actually share very little in common, apart from affecting the bowel. I was under the impression that IBS could lead to IBD, or if you had IBS you were at a higher risk for IBD, or some such thing. But the mechanisms of the two diseases are so different that there is actually little overlap.

Inflammatory Bowel Disease causes the immune system lying below the mucosal layer of the bowel to over react to antigens passing through the lumen of the bowel. The two main types of disease causing this are Crohn's disease and Ulcerative Colitis, as mentioned in a previous blog. With Irritable Bowel Syndrome, nerve endings in the bowel are sensitive or "irritable", causing spasms, but otherwise the tissue in the bowel is normal. There are some similarities in symptoms, which is to be expected if both IBD and IBS are affecting the bowel's function. But IBS should never cause anemia, bleeding, permanent damage to the bowel or weight loss, which can be symptoms of IBD. While IBD is obviously an inflammatory condition, IBS is considered a "functional disorder", because it presents normal-looking bowel tissue. Thus, IBS can only be diagnosed by clustering symptoms (hence the term "syndrome"), while IBD can be diagnosed by taking a biopsy of bowel tissue. Obviously IBS is less serious than IBD, and will not put someone with the disease at a higher risk for colon cancer like having IBD can.

I just thought the distinctions were interesting, especially since I went into studying IBD thinking IBD and IBS were so similar.