1. What are the causes of chronic diarrhea?
Diarrhea that lasts more than 3-4 weeks is chronic. The causes of chronic diarrhea can be many and varied. According to the pathophysiological mechanisms of diarrhea, the causes are divided into secretory, osmotic, steatorrhea (diarrhea with an oily consistency), inflammatory, motility disorders (peristalsis), and others.
Secretory diarrhea is caused by disturbances in the transport of fluids and electrolytes through the intestinal mucosa. This type of diarrhea is characterized by passing large amounts of watery stools. These bowel movements are painless and continue even when fasting. Causes of secretory diarrhea include:
- Side effects of medications – chronic use of laxatives, alcohol, long-term ingestion of certain environmental toxins (for example, arsenic), long-term infections, and others can also be causes of chronic diarrhea.
- Bowel resection
- Hormonal causes – a rare cause of chronic diarrhea can be tumor formations producing hormones or active substances. Such tumors are gastrinoma, colorectal villous adenoma, and others.
- Congenital defects of ion absorption. They appear after birth.
In diarrhea caused by osmotic reasons, liquids are drawn from the body into the intestine by certain substances called osmotically active. In such cases, the diarrhea intensifies when the amount of the substance increases, and vice versa – it disappears when fasting. Causes of osmotic diarrhea include:
- Osmotic laxatives (lactulose, Epsom salt)
- Carbohydrate malabsorption – when certain carbohydrates are not absorbed, they remain in the intestine and prevent the water in it from being absorbed as well. The most common such condition is lactose intolerance, in which the lactose in dairy products is not absorbed and their intake causes diarrhea, abdominal bloating, and discomfort.
In diarrhea accompanied by steatorrhea – an increased amount of fat in the stool, the amount of fat is increased by the osmotic properties of the fatty acids, which drag water with them. Such diarrhea is characterized by stools with a bad smell, greasy consistency, and difficulty flushing when flushing the toilet. Steatorrhea is most often due to fat malabsorption and is accompanied by weight loss due to impaired absorption of fat-soluble vitamins. Causes of diarrhea accompanied by steatorrhea include:
- Chronic pancreatitis, obstruction of the pancreatic duct
- Impaired absorption of nutrients in the intestinal mucosa. It can be caused by several intestinal diseases, but most commonly it is due to gluten enteropathy (gluten intolerance), tropical sprue (a tropical form of gluten intolerance), and others.
Inflammatory diarrhea is accompanied by pain, fever, and other manifestations of the inflammatory process. The mechanism of these diarrheas can be very different – depending on the cause, but the unifying feature is the high amounts of protein and leukocytes in the feces. Loss of protein through the feces – in severe inflammatory processes, can lead to generalized edema (anasarca). Any middle-aged or elderly person suffering from chronic diarrhea of the inflammatory type should be examined by a doctor to rule out a tumor formation in the intestine as the cause of the disease. Causes of chronic inflammatory diarrhea include:
- Inflammatory bowel diseases such as Crohn’s disease and chronic ulcerative colitis
- Primary and secondary forms of immunodeficiency. They can be the cause of prolonged infections leading to chronic diarrhea.
- Other causes – radiation enterocolitis, chronic graft-versus-host reaction, eosinophilic enterocolitis, and others.
Motility disorders (peristalsis) accompany other types of diarrhea, but as a primary cause of diarrhea, they are rare. Causes of this type of diarrhea include:
- Irritable bowel syndrome
- Medications from the group of prokinetics (stimulating peristalsis)
- Diabetic diarrhea
2. When should we see a doctor for chronic diarrhea?
For any diarrhea lasting more than 3-4 weeks, you should consult a doctor to confirm or exclude the many serious diseases that can be its cause. History, physical examination, and routine blood tests help establish the mechanism of diarrhea and direct the physician to order other tests. Such studies are:
- X-ray of abdominal organs
- food avoidance test – this test involves avoiding a certain food to determine if the diarrhea is caused by an allergy or food intolerance
- sigmoidoscopy – using a special instrument, the doctor examines the inside of the rectum and the lower part of the large intestine
- colonoscopy – similar to sigmoidoscopy, but in this case the entire colon is examined.
3. What is the treatment for chronic diarrhea?
Treatment of chronic diarrhea depends on its cause. It can be curative, symptom-suppressive, or empiric.
If the cause can be removed, the treatment is curative, as in the resection of colorectal carcinoma or stopping the medication causing the diarrhea.
In many chronic diseases, diarrhea can be controlled by suppressing the causative mechanism. An example of this is the avoidance of dairy products in case of lactose intolerance or the administration of corticosteroids in inflammatory bowel diseases, adsorptive agents such as cholestyramine in malabsorption of bile acids, taking omeprazole in gastrinomas or enzyme replacement preparations in pancreatic diseases.
When the cause of chronic diarrhea is unclear, empiric treatment is helpful until it is. Mild opiates such as loperamide or diphenoxylate may help with mild to moderate diarrhea. Such preparations that suppress peristalsis should be avoided in irritable bowel syndrome. Clonidine helps control diabetic diarrhea. Patients with steatorrhea may require additional intake of fat-soluble vitamins.
In all patients with chronic diarrhea, restoring lost fluids and preventing dehydration is a major part of therapy.
