ArcaMax

DEAR DR. ROACH: I'm a 67-year-old female in pretty good health. The only medications I take are for my thyroid, arthritis and hormone replacement. Early last year, I was sick with a cold/flu for a couple of weeks and had diarrhea during this time. I figured it was from my sickness; however, the sickness went away, but the diarrhea did not.

Over the next few months, I saw a gastroenterologist and had blood work, a fecal sample, and a colonoscopy done. The tests showed nothing wrong other than an inflamed colon. At the initial gastro visit, she prescribed "something to help," which turned out to be cholestyramine powder. This is the only thing that has helped my condition. If I stop taking it, my diarrhea comes back.

I did some research, and I believe my condition is called bile acid malabsorption. I have no idea why I have this condition. Are there any more tests I should take, or should I just live with this and keep taking this awful gritty powder? -- B.M.

ANSWER: The only time I have recognized bile acid malabsorption has been in people who have a reason for it. In my practice, this is mainly people who have had their gallbladders taken out. The gallbladder stores bile, which contains bile acids and bile salts. When you eat, the gallbladder squeezes and releases the bile salts you need to properly break down fats into a form that your body can absorb.

Without a gallbladder, the liver, which makes bile acids that are later turned into bile salts, releases bile salts continuously. This can sometimes overwhelm the small bowel's ability to reabsorb and recycle them. (In most people, the intestine learns to absorb enough bile salts.) Once bile acids and salts get into the colon, they cause diarrhea.

For people with persistent diarrhea after gallbladder surgery, a bile acid binder like cholestyramine can make a huge difference in their quality of life, and I have seen patients who were suffering for years before they were prescribed this treatment.

A second group of patients I have recognized bile acid malabsorption in are those who have had part of the intestine (usually the last part, the ilium) removed surgically or who have damage to the ilium. Damage can be due to Crohn's disease, uncontrolled celiac disease, or radiation. Given the inflammation that the gastroenterologist saw in your colon, I would be concerned about an inflammatory bowel disease such as Crohn's.

There is also a group of people who just overproduce bile acids. This has been a hard group to identify partly because this disease isn't particularly well-known by generalists, but also because the diagnostic tests have been hard to use. I have probably missed this diagnosis in the past. However, there is now a blood test (7AlphaC4) and a stool test (a fecal bile acid test performed on a 48-hour stool collection) to help make the diagnosis.

Finally, I know it's not an issue in you, but the drug metformin can cause excess bile acid secretion, which is one of the ways that metformin can cause diarrhea. Often the body adjusts, and the diarrhea goes away, but some people have been misdiagnosed as having irritable bowel syndrome when the cause of their chronic diarrhea is metformin.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu.

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