What Is Chronic Diarrhea?
In resource-rich countries, the common causes of chronic diarrhea are:
- Irritable bowel syndrome (IBS)
- Inflammatory bowel disease
- Malabsorption syndromes (lactose intolerance and celiac disease)
- Chronic infections (especially in the immunocompromised)
Chronic diarrhea puts patients at risk for dehydration, hypovolemia, electrolyte disturbances, and anal fissures and other local irritations.
Irritable Bowel Syndrome
IBS typically presents with abdominal pain and various bowel habits, such as alternating diarrhea and constipation, or normal bowel movements with alternating diarrhea and constipation. Half of those with IBS have mucus discharge. The type of IBS is associated with functional bowel habits, such as IBS with predominant diarrhea or IBS with mixed bowel conditions.
Many medications list diarrhea in their side effects. These can be due to alteration in flora, bowel motility, colonic overhydration, or allergic reactions.
Inflammatory Bowel Disease (IBS)
IBS is most commonly associated with Crohn disease and ulcerative colitis (UC), but it can refer to any intestinal inflammatory condition.
- Crohn disease: inflammation can involve any and all of the entire gastrointestinal tract from mouth to anus. It causes diarrhea, abdominal pain, and fever. There can be bloody stools, but this is more common with ulcerative colitis.
- Ulcerative colitis: this can have varying degrees of severity. Mild disease involves the rectum or rectosigmoid colon; rectal bleeding and mucus passage are associated with diarrhea, but constipation can appear from time to time. Moderate UC involves more than the end of the colon, going up to the left upper quadrant of the abdomen–where the descending colon begins. Frequent diarrhea, bloody stools can number 10/day and cause a mild anemia and low grade fever. Severe disease involves much of the entire large colon.
Impairment of absorption from the intestines can be hereditary or develop as a consequence of Crohn disease, celiac disease, or surgical resection. Maldigestion is the impairment in the production or quality of digestive juices. Malabsorption syndrome covers a variety of disorders:
- Lactose intolerance
- Celiac disease
- Small bowel bacterial overgrowth
- Chronic pancreatitis
Chronic infections should be considered if there is a history of travel, antibiotics, or HIV infection.
How Is Chronic Diarrhea Diagnosed?
90% of those with chronic diarrhea will have the cause diagnosed. A history of the timing and consistency of stool, as well as travel history and family history aid diagnosis.
Blood Tests Useful in Chronic Diarrhea
- Complete Blood Count: Will diagnose anemia and will indicate infection from the white blood cell (WBC) count
- Serum electrolytes: Sodium, potassium, chloride, calcium, etc
- Inflammatory Markers: Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)
- Functional assessment: Via total protein and albumin and thyroid function tests
- Serologic testing for celiac disease
Stool Test Useful in Chronic Diarrhea:
- Evaluation for occult blood
- Microscopic exam for parasites
- Stool cultures
- Sigmoidoscopy or Colonoscopy (preferred) with possible biopsies
- X-rays, abdominal CT, and/or MRI
Management of Chronic Diarrhea
One fourth to half of all referrals to gastroenterologists is for irritable bowel syndrome due to its chronic abdominal pain and altered bowel habits. Treatment includes alteration of the diet to avoid gassy foods and fermentables, and possibly lactose and gluten when there is malabsorption. Fiber can be added.
Management of chronic diarrhea, first and regardless of the cause, must treat dehydration and electrolyte disturbances if present. This is done either via increased intake (oral and parenteral) or decreased output, via reducing intestinal motility.
- Oral fluids
- Intravenous fluids with electrolyte supplementation if needed
- Anti-diarrheal agents via inhibition of of motility and peristalsis, such as loperamide and eluxadoline (opioid agonist/antagonist); bile acid sequestrants, such as cholestyramine, colestipol, and colesevelam; or serotonin antagonists such as alosetron
- Antispasmodics such as dicyclomine and hyoscyamine
- Antidepressants for their anticholinergic properties which slow intestinal transit time
Other remedies include probiotics and fecal transplantation.
For the other causes of chronic diarrhea, treatment beyond what is cited above is individualized to the patient and the etiology:
Those with inflammatory conditions may be treated with a combined approach of immunosuppression via glucocorticoid steroids and anti-biological therapy.
Those with drug-related diarrhea are given a trial-and-error approach of substituting equally effective medications.
Those with microbial infections should be treated with antibiotics or anti-parasitic medications.
Prevention of Chronic Diarrhea
Prevention of chronic diarrhea depends on the cause:
- For the inflammatory diarrheal illnesses IBS and Crohn disease: This is limited to suppression of symptoms
- For infectious causes: Prevention is based on barriers to exposure, such as avoiding contaminated foods and liquids, especially during travel
- For the irritable bowel and malabsorption syndromes: Such as celiac disease and gluten intolerance, avoidance of the irritants and other diet alterations are necessary
- For drug-related diarrhea: Prevention hinges on finding equally effective substitutes that do not alter the gut microbiome or stimulate hypermotility
- For diarrhea related to food allergies: Allergy testing for specific food groups can be helpful in preventing diarrhea