IBS is often at play
Once these causes have been ruled out, several etiological pathways should be investigated. The first relates to motility issues, which are the most common diarrhea-related problem, said Dr. Hammoudi.
This type of diarrhea is linked to rapid intestinal transit time and is characterized by postprandial bowel movements (occurring shortly after a meal). Here, patients experience urgency and notice identifiable food debris in their stools. It tends to stop when fasting and can be treated effectively with antidiarrheals.
Irritable bowel syndrome (IBS) is the main cause of rapid intestinal transit diarrhea. It is defined as recurrent abdominal pain (at least 1 day/week) over a period of 3 months, associated with two of the following criteria: pain eases or worsens on passing feces, change in frequency of bowel movements, change in the consistency of stools.
Symptoms may come on suddenly, sometimes after taking antibiotics, and may result in misdiagnosis.
IBS medications treat the symptoms. Antispasmodics, such as trimebutine, phloroglucinol (Spasfon), or pinaverium bromide (Dicetel) are recommended, even there can be a placebo effect. The antidiarrheal medication loperamide (Imodium) can also be used. Probiotics may be beneficial, as an imbalanced intestinal microbiota is often implicated.
Dietary changes can also have a positive impact. Encouraging a diet rich in fruit and vegetables to enhance fiber intake is advised. A low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet, targeting short-chain carbohydrates, can also be tried to identify foods to avoid, although it may be challenging to stick to.
Postinfectious IBS is a frequent cause of rapid intestinal transit diarrhea. It generally follows an episode of acute infectious diarrhea. “Symptoms may come on suddenly, sometimes after taking antibiotics, and may result in misdiagnosis,” said Dr. Hammoudi. This type of IBS often resolves spontaneously within 6 months.
Consider the possibility of SIBO
Another cause of rapid intestinal transit diarrhea is small intestinal bacterial overgrowth (SIBO). It is difficult to distinguish between IBS and SIBO. Often, affected patients are diabetic, overweight, or have had bowel surgery.
The only way to diagnose SIBO is by conducting a breath test to measure the production of hydrogen and methane by the microbiota after ingesting sugar. However, the test is difficult to access and not fully covered by social security plans in France, said Dr. Hammoudi.
In cases of suspected SIBO and severe symptoms, a 7- to 10-day course of antibiotics can be attempted to provide relief, although a diagnosis should be confirmed before considering this option, Dr. Hammoudi said.
Malabsorption diarrhea
Another major cause of chronic diarrhea is malabsorption, characterized by large, fatty stools that are difficult to flush. Despite a normal diet, this type of diarrhea is associated with weight loss and nutritional deficiencies.
Its diagnosis involves measuring fat in the stools (steatorrhea) and possibly testing fecal elastase, an enzyme produced by the pancreas that is involved in digestion.
The most important causes of malabsorption diarrhea are pancreatic insufficiency, celiac disease, and Crohn’s disease. Generally, any lesion in the small intestine can lead to malabsorption-related diarrhea.
Celiac disease, or gluten intolerance, is an autoimmune condition triggered by a reaction to gluten proteins. Several antibodies can be produced in the presence of gluten proteins. Diagnosis is confirmed by positive antitransglutaminase antibodies and a duodenal biopsy through esophagogastroduodenoscopy.
The only treatment for celiac disease is a lifelong gluten-free diet. Celiac disease is increasingly diagnosed in adults, said Dr. Hammoudi, and should be considered as a possibility. This condition must be distinguished from gluten sensitivity, which can cause digestive issues, possibly leading to rapid intestinal transit diarrhea. “The only treatment for celiac disease is a lifelong gluten-free diet,” Dr. Hammoudi added.
Crohn’s disease, a type of inflammatory bowel disease, affects the entire digestive tract, particularly the terminal small intestine, which promotes malabsorption. In ulcerative colitis, another IBD affecting the rectum, any associated rectal syndrome can result in false diarrhea with stools containing blood and mucus.
Osmotic diarrhea, on the other hand, is linked to the presence of highly osmotic agents in the digestive tract. This type of diarrhea is watery and short-lived, stopping once the agents are no longer absorbed. The main culprits are lactose (in cases of lactose intolerance) and laxatives.