digestive disorders
Diarrhea in Adults
Causes of Diarrhea
There are many different causes of diarrhea, depending on how long the diarrhea has lasted ( see Table: Some Causes and Features of Diarrhea ). The most common causes of acute diarrhea (lasting less than a week) are Infection with viruses, bacteria, or parasites ( Overview of Gastroenteritis ) Overview of Food Poisoning None Drug side effects The most common causes of chronic diarrhea (lasting more than 4 weeks) are Irritable Bowel Syndrome (IBS) None Overview of Inflammatory Bowel Disease (IBD) None Drug side effects Overview of Malabsorption None Diarrhea that has been present for more than 4 weeks may be a lingering case of acute diarrhea or the early stage of a disorder that causes chronic diarrhea. Normally, stool is 60 to 90% water. Diarrhea occurs when not enough water is removed from the stool, making the stool loose and poorly formed. Stool may contain too much water if it Passes too quickly through the digestive tract Contains certain substances that prevent the large intestine from absorbing water Contains excess water secreted by the intestines is a common cause of diarrhea. For stool to have normal consistency, it must remain in the large intestine for a certain amount of time. Stool that leaves the large intestine too quickly is watery. Many medical conditions and treatments can decrease the amount of time that stool stays in the large intestine. These conditions include an overactive thyroid ( Hyperthyroidism ); deficiency drink milk or eat dairy products, lactose is not digested. As lactose accumulates in the intestine, it causes osmotic diarrhea—a condition known as Lactose Intolerance . The severity of osmotic diarrhea depends on how much of the osmotic substance is consumed. Diarrhea stops soon after the person stops eating or drinking the substance. Blood in the digestive tract also acts as an osmotic agent and results in black, tarry stools (melena). Another cause of osmotic diarrhea is an overgrowth of normal intestinal bacteria or the growth of bacteria normally not found in the intestines. Antibiotics can cause osmotic diarrhea by destroying the normal intestinal bacteria. , and bile acids (which may build up after surgery to remove part of the small intestine). Certain rare tumors—such as carcinoid, Gastrinoma , and Inflammatory diarrheaoccurs when the lining of the large intestine becomes inflamed, ulcerated, or engorged and releases proteins, blood, mucus, and other fluids, which increase the bulk and fluid content of the stool. This type of diarrhea can be caused by many diseases, including ulcerative colitis, Crohn disease, tuberculosis, and cancers such as lymphoma and adenocarcinoma. When the lining of the rectum is affected, people often feel an urgent need to move their bowels and have frequent bowel movements because the inflamed rectum is more sensitive to expansion (distention) by stool. Diarrhea caused by Overview of Malabsorption None 