Diarrhea is a very common symptom that affects all of us from time to time and is generally transient in nature, treated successfully by over-the-counter medications or altered diets. Patients generally seek medical attention when their diarrhea becomes more pronounced, prolonged, associated with fever, abdominal pain or rectal bleeding. There are many different conditions that can lead to diarrhea, so on visiting your doctor, a detailed and accurate history is important. Your doctor will likely ask about the frequency, volume, duration and consistency and quality of the stool along with associated symptoms such as blood, mucous, puss, abdominal pain, fever, weight loss, etc. Knowledge of your medications is important, especially if there has been a change recently as these can certainly affect one's bowel habits. Also it is very important to know what other underlying medical conditions the patient may have as this could be involved or result in diarrhea as well. In that regard, all medical problems, past surgeries and family history are important factors in considering the cause for diarrhea. Additionally, a travel history is very important to know as well as one's diet, medications, be they prescription or over-the-counter. The influence of psychological stress on diarrhea cannot be discounted. In addition, a thorough dietary history is important to know as certain poorly absorbed foods might lead one to have symptoms of diarrhea. The physical examination is also important and your doctor will likely evaluate your vital signs, temperature, and general, overall physical condition with particular attention to the abdomen. Stool samples for culture and the detection of blood is also important. In the evaluation of diarrhea in any patient we like to classify diarrhea as either acute or chronic in nature.
Acute diarrhea is generally defined as diarrhea that has been present for less than several weeks. It presents with a sudden change in bowel habits resulting in loose and frequent stools more voluminous in nature, sometimes associated with fever, malaise and/or dehydration.
Infections are the most common cause of acute diarrhea and the most common organisms we see are E. Coli, Salmonella, Shigella, Clostridium Difficile (C. Difficile), Campylobacter and Giardia as well as a variety of viral causes. Food poisoning is another cause of acute diarrhea, which is a result of various bacteria infecting food that has generally been stored improperly.
Numerous medications may also cause diarrhea and can include antacids, antibiotics, antihypertensive medications, laxatives, magnesium supplements, potassium supplements and various cardiac medications. In addition, ingestion of poorly absorbed sugar may result in diarrhea in certain people and these include fructose, lactose, mannitol and sorbitol. Some of these products are present in sugarless foods or drinks, and this is a quite common cause of acute diarrhea.
The evaluation of acute diarrhea consists of a visit with the doctor that includes a history and physical examination. Sometimes a flexible sigmoidoscopy is performed to look at the lining of the colon and stool cultures and analysis can be obtained to look for infectious causes. Blood tests or abdominal x-rays may also be considered. Treatment for acute diarrhea consists mainly of fluid and electrolyte repletion along with antibiotics and anti-diarrheal agents. Most patients generally respond well to outpatient treatment but on occasion if severe dehydration develops or signs of toxicity occur like fever or severe pain, then in that situation the patient may need to be hospitalized.
Chronic diarrhea is defined as diarrhea that persists for more than 4 weeks. Infections are generally not a cause for chronic diarrhea, so one must consider other medical conditions that may lead to a chronic diarrhea state. Causes for chronic diarrhea are numerous but we may see this condition after certain surgeries are performed; in particular, a vagotomy or gastrectomy, cholecystectomy (gallbladder removal) or bowel resection. In addition, abdominal pelvic radiation therapy could lead to chronic diarrhea. Drug-induced diarrhea may be from various medications and sometimes the patient is not aware that a medication may be leading to diarrhea symptoms. An example may be as simple as an antacid, which if a patient is taking on a regular basis could lead to diarrhea, as most of these contain magnesium.
Various endocrine diseases could cause chronic diarrhea, such as hyperthyroidism, diabetes mellitus, hypoparathyroidism or Addison's disease. Circulatory problems like congestive heart failure, vasculitis or poor bowel circulation can also lead to diarrhea and immune deficiency syndromes like AIDS or various neurologic diseases might also lead to chronic diarrhea. Chronic bacterial infections also can be a cause and the most common of these would be parasites like Giardia, Strongyloides, Yersinia, or tuberculosis.
A common cause of chronic diarrhea may be inflammatory bowel disease, usually called Crohn's disease, ileitis, or ulcerative colitis, these conditions lead to chronic inflammation of the lining of the bowel wall, resulting in seepage of secretions, mucous, blood and hypermotility all resulting in chronic diarrhea. Occasionally diverticulitis of the colon or a collagenous colitis might also be a factor. In addition, tumors of the colon, especially if they are in the lower part of the colon could cause diarrhea. These could be either colon cancers or colon polyps as well as abdominal lymphomas or carcinoid tumors. Certain glandular tumors like pancreatic carcinoma, gastrinoma, thyroid carcinoma or carcinoid tumors can also lead to diarrhea.
Maldigestion or malabsorption is another not uncommon cause of diarrhea. This could be secondary to a decrease in production of digestive enzymes from either the pancreas or the bile resulting in poor absorption and thus diarrhea. Additionally, there are various conditions of the lining of the small intestine which prevent absorption of food and nutrients and therefore result in a diarrhea state, and these can be reviewed under the section of malabsorption.
In order to diagnose the cause of chronic diarrhea, often times a rather extensive work-up is necessary. First of all it includes a careful history and physical examination. Various other tests are employed including blood counts, serum chemistries, liver function and thyroid tests, urine evaluation, stool examination for bacteria as well as parasites and blood and a possible stool collection for fat or electrolytes. Colonoscopy and/or upper endoscopy are frequently employed to evaluate the inside of the GI tract and take specimens if necessary. Occasionally upper or lower GI x-rays are also employed as well as abdominal and pelvic sonography or computerized CAT scans of the abdomen. There is no one treatment for chronic diarrhea as the approach is dependent upon the actual cause, so once a work-up is completed, therapy can be directed at the specific cause for the chronic diarrhea. In rare cases, no cause is determined and this is called a chronic idiopathic diarrhea, in which case dietary manipulation and various anti-diarrheal medications are employed.
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