• 14Jun

    Chronic diarrhea – what are the possible causes?

    Diarrhea is the passage of either watery or unformed stools occurring at an increased frequency. In people on low fiber diet or western diet, a stool weight of more than 200 grams may be considered as diarrhea. If the diarrhea lasts for more than four weeks, it is defined as chronic diarrhea.

    In certain diseases, there is frequent passage of small volumes of stool amounting to less than 200 grams daily. This is called false diarrhea or ‘pseudo-diarrhea’ and is seen in irritable bowel syndrome or inflammation of rectum. Chronic diarrhea may also be differentiated from another condition called fecal incontinence. In this condition the voluntary control of passage of stools is lost due to neuromuscular disorders. Another condition seen in patients with fecal impaction in the rectum is passage of mucus with small amount of stools, and is called overflow diarrhea. These conditions should be kept in mind when a patient presents with a long standing diarrhea. A careful history and physical examination generally allow these conditions to be discriminated from true diarrhea.

    Chronic Diarrhea causes

    Any diarrhea lasting for more than four weeks is a matter of concern. Most of these cases of chronic diarrhea are not related to intestinal infection. The causes of this condition are multiple. It is therefore classified on the basis of mechanism of causation or pathogenesis of diarrhea. These causes include secretory, osmotic, fatty, inflammatory and motility related.

    Secretory causes of diarrhea

    This diarrhea is due to an abnormal transport of fluid and electrolytes in the mucosa of small and large intestine. The diarrhea is watery, large volume, painless and persists even on fasting. This is most commonly caused by drugs or toxins. Though many drugs are implicated, the common ones include antibiotics, cardiac anti-arrhythmic drugs, anti-hypertensives, non-steroidal anti-inflammatory drugs (NSAIDs), cancer drugs, antacids and laxatives. Chronic alcohol intake has harmful effects on the mucosal cells of intestine and may result in chronic diarrhea. Arsenic poisoning is known to cause chronic diarrhea.

    Any diarrhea lasting for more than four weeks should be a matter of concern.

    Any diarrhea lasting for more than four weeks should be a matter of concern.

    Resection of intestine is an important cause of secretory diarrhea as it reduces the area for reabsorption of secreted fluids and electrolytes. Certain endocrine tumors like carcinoid tumor involving liver or bronchus produce watery diarrhea. The other features of carcinoid syndrome may present as flushing, wheezing, difficulty in breathing and heart disease in these patients. The hormones responsible are serotonin, histamine, prostaglandins and kinins. The other endocrine tumors associated with watery diarrhea include gastrinoma, VIPoma and medullary carcinoma of thyroid.

    Osmotic diarrhea

    Osmotic diarrhea occurs due to osmotic effect of non-absorbable contents in the intestine. The diarrhea stops after fasting or with discontinuation of the causative agent. The causes include osmotic laxatives and lactose intolerance in adults.

    Fatty diarrhea

    This occurs due to malabsorption of fats. The diarrhea is foul smelling, bulky, greasy, sticky and difficult to flush. It is associated with weight loss and features of malabsorption. Chronic pancreatitis, which is usually related to alcohol consumption, is an important cause of fatty diarrhea.

    Celiac disease due to gluten sensitivity also presents with above features. A similar clinical picture is seen in patients with AIDS and results from mycobacterium avium-intracellulare infection.

    Inflammatory diarrhea

    These diarrheas are associated with features of inflammation like abdominal pain and fever. The inflammation leads to leakage of fluids though other features like fat malabsorption; poor reabsorption of fluids and electrolytes is also seen. The stools on microscopic examination show white cells which distinguishes this from other causes of diarrhea. This is seen in conditions like Crohn’s disease and ulcerative colitis.

    Motility related diarrheas

    Abnormally rapid motility of intestine can cause diarrhea and is seen in conditions like hyperthyroidism and carcinoid syndrome. A reduced motility may result in stasis and secondary bacterial infection, resulting in diarrhea. This is seen in neuropathies involving the intestines as in patients with diabetes.

    Diarrhea, when prolonged, may be related to another underlying disease. A physician consult should be taken to find out its cause. Early treatment helps in prevention of malnutrition and weight loss. The treatment of primary cause is essential and improves the quality of life.

    Anna L.

    It’s all about health!
    I have academic background in drugs related Chemical Technology, as well as extensive professional experience in pharma and medical companies. My main area of interest is everyday life medicine. The goal of my articles is to give people informative answers to the questions that bother them, to dispel doubts and some common misbeliefs and also to inspire everyone to keep healthy lifestyle.

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