Diarrhea

Overview
Common causes
Tests
Prevention
Treatment
Sources

Tests
Your doctor will want to ask you about your diarrhea. The frequency, quantity, and consistency of normal bowel movements are very individual. They depend on your metabolism, the foods you eat, your activity level, the amount of fluids you drink, the medications you take, and even any stress that you are experiencing. Your doctor will be looking for things that are out of the ordinary and for alterations that are commonly associated with diarrhea-causing conditions. Your doctor will be asking you a series of questions that allow him to make informed choices about which laboratory tests will be the most appropriate in your situation. These questions may include:

What is the frequency of your stools?
How long you have been experiencing diarrhea?
What are the consistency, color, and approximate volume of the stools?
Is there blood or mucus in the stool?
What other symptoms are you having: abdominal pain, nausea, fever, headache, fatigue?
What and where have you eaten recently?
Have you been camping? Have you traveled outside of the U.S.? where?
Are any of your family members, close acquaintances, or co-workers ill?
Have you been on antibiotics lately?

Laboratory Tests
If your diarrhea is uncomplicated and goes away within a few days, your doctor may not search for the cause of your gastrointestinal upset. He may order one or more of the following tests, however, if your diarrhea is severe, if there is blood or mucous present, or if it is continuing unabated. This is especially true if you have been outside the United States and/or have eaten or drunk anything that has also made someone close to you ill. Testing may include:

O&P (Ova and Parasite) testing. A microscopic evaluation of your stool for parasites and the ova (eggs, cysts) of parasites.
Stool WBC. White blood cells may be present in the stool when there is a bacterial infection.
Stool or fecal fat. Sometimes fat is seen in the stool with malabsorption disorders.
Stool Culture. To check for pathogenic gastrointestinal bacteria.
Antigen tests for giardia, cryptosporidium & E. histolytica. These tests detect protein structures on the parasites. They are more sensitive and specific for these particular parasites than the O&P microscopic exam.
Food Allergy and intolerance tests. Such as tests for lactose intolerance.
Celiac disease tests. Such as anti-endomysial and anti-gliadin antibodies.
Antibody tests for parasites. These are not as useful to detect current infections but may be ordered to check for past or chronic infections, especially if unusual parasitic infections are suspected.
Rotavirus test. A rapid antigen test.
Clostridium difficile toxin. A rapid test used to identify a Clostridium difficile infection, by detecting the toxin made by the bacteria.
Electrolytes. If you are dehydrated, your doctor may want to do a blood test to determine whether your electrolytes have become imbalanced.
Biopsy of the small intestines (rare). To look for signs of parasitic infection.

Non-Laboratory Tests
Sometimes, special procedures are used to look at portions of the gastrointestinal tract. See the National Institute of Diabetes and Digestive and Kidney Diseases website pages on endoscopy, colonoscopy and sigmoidoscopy for more on these.