Causes of chronic diarrhea
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Common Causes of Chronic Diarrhea
Chronic diarrhea, defined as loose stools lasting more than four weeks, can have many causes. The most common causes include functional disorders like irritable bowel syndrome (IBS), infections (especially in immunocompromised individuals), malabsorption syndromes, inflammatory bowel diseases, medication side effects, and less commonly, endocrine or systemic diseases Gale2019Burgers2020Ünal2017+2 MORE.
Infectious Causes of Chronic Diarrhea
While most infectious diarrhea is acute, some pathogens can cause chronic symptoms. Parasites such as Giardia lamblia, Cryptosporidia, and Cyclospora are the most likely infectious causes, especially in immunocompetent individuals Lee2001Kaiser2012Gale2019+1 MORE. Certain bacteria, including Yersinia, Plesiomonas, and Aeromonas, may also cause chronic diarrhea, but this is rare in healthy people . Immunosuppressed individuals, such as those with HIV, are at higher risk for persistent infections from bacteria like Campylobacter and Salmonella . Infections can also trigger chronic conditions like IBS or inflammatory bowel disease after the initial infection has cleared Lee2001Kaiser2012.
Malabsorption and Maldigestion Syndromes
Chronic diarrhea can result from malabsorption or maldigestion. Conditions such as celiac disease, pancreatic exocrine insufficiency, and small bowel bacterial overgrowth (SBO) are notable causes. SBO, in particular, is a common but often underdiagnosed cause of chronic non-specific diarrhea Gale2019Teo2004Burgers2020+1 MORE. Fatty diarrhea (steatorrhea) is a hallmark of malabsorption syndromes Burgers2020Ünal2017.
Inflammatory and Autoimmune Disorders
Inflammatory bowel diseases (IBD), such as Crohn’s disease and ulcerative colitis, are significant causes of chronic diarrhea. These conditions are characterized by inflammation of the gastrointestinal tract and may present with blood in the stool, weight loss, and other systemic symptoms Burgers2020Ünal2017López-Valle2023. Autoimmune conditions like celiac disease are also increasingly recognized as causes of chronic diarrhea, especially in developed countries Gale2019Burgers2020.
Medication-Induced and Functional Causes
Many medications can cause chronic diarrhea as a side effect, including certain antibiotics, antacids, and psychiatric medications Gale2019Ünal2017Sathiyasekaran2023. Functional disorders, particularly IBS and functional diarrhea, are among the most common causes in adults and are diagnosed when no structural or biochemical abnormalities are found Burgers2020Ünal2017Camilleri2016.
Endocrine and Systemic Causes
Endocrine disorders, such as hyperthyroidism and neuroendocrine tumors, can lead to chronic diarrhea through increased intestinal secretion or motility Burgers2020Ünal2017Chu2020. Other systemic diseases, including immune deficiencies and malignancies, are less common but important to consider, especially in children or those with other symptoms .
Diagnostic Approach
A thorough history and physical examination are essential to guide further testing. Laboratory tests, stool studies, and sometimes endoscopic evaluation help categorize diarrhea as watery, fatty, or inflammatory, which can narrow down the possible causes Burgers2020Ünal2017Camilleri2016. Identifying “red flag” symptoms, such as weight loss, blood in stool, or family history of colon cancer, is crucial for early detection of serious conditions .
Conclusion
Chronic diarrhea has a wide range of causes, from common functional disorders and infections to malabsorption, inflammatory diseases, medications, and rare systemic conditions. Careful evaluation and targeted testing are key to identifying the underlying cause and guiding effective treatment Lee2001Kaiser2012Gale2019+7 MORE.
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