Phys final review -- diarrhea.pdf

Diarrhea Disease summary ○ Definition: is defined as an increase in the frequency of bowel movements, a decrease in the form of stool (i.e., greater looseness and fluidity of stool) or a combination of these 2 features ○ Thus if an individual who usual...

Diarrhea Disease summary ○ Definition: is defined as an increase in the frequency of bowel movements, a decrease in the form of stool (i.e., greater looseness and fluidity of stool) or a combination of these 2 features ○ Thus if an individual who usually has one bowel movement each day begins to have three bowel movements daily, diarrhea is present ○ The consistency of stool can vary considerably in healthy people depending on diet ○ For example, people who eat large amounts of vegetables will have looser stools than people who eat few vegetables ○ Individuals who develop looser stools than usual have diarrhea even though stools may be within the range of normal and respect to consistency ○ Stools that are liquid or watery are always abnormal and considered diarrheal. Diarrhea may be acute or chronic ○ The distinction is important because these 2 types of diarrhea have different causes and require different treatment ○ Acute diarrhea usually lasts several days but may persist for as long as week ○ Diarrhea is considered chronic when symptoms persist for 3 weeks in children and adults and 4 weeks in infants ○ Commonly used alternative phrases for diarrhea include: watery stools, frequent bowel movements, and loose bowel movements Significance ○ Diarrhea can range from mild, self-limited (i.e., resolves spontaneously) episode to severe, life threatening illness ○ The most serious consequences of severe or prolonged diarrhea are dehydration (i.e., excessive loss of body fluids) that may progress to shock, kidney failure, and electrolyte deficiencies, especially sodium and potassium but also chloride and bicarbonate ○ Most deaths from diarrhea occur in the very young and the elderly, whose health may be put at risk from only moderate dehydration ○ Diarrhea in adults is often mild and resolves quickly without complication ○ However, infants and children can become dehydrated quickly ○ Approximately 400 children in the United States die from complication of diarrhea each year ○ Globally, 2 million children are estimated to die annually from a diarrheal illness, making the condition the second leading cause of death in children after respiratory infections ○ Diarrhea may also cause significant irritation to the anu from the frequent passage of watery stool  Causes and risk factors ○ The most common cause of acute diarrhea is infection –primarily viral, but also bacterial and parasitic ○ Viral gastroenteritis (i.e., infection of the stomach and small intestine) is the most common cause of acute diarrhea worldwide ○ Viral gastroenteritis can occur sporadically (i.e., as isolated cases) or as an epidemic ○ Sporadic diarrhea is caused by a variety of different viruses and is believed to spread by person-to-person contact. The most common cause of epidemic diarrhea (e.g., nursing homes, schools, or on cruise ships) is calicivirus ○ Caliciviruses are transmitted by food that is contaminated by sick food handlers or by person-to-person contact ○ Rotavirus is the most common cause of severe acute diarrhea in infants and young children ○ Norwalk virus is the most common cause of epidemic diarrhea among school-aged children and adults and adenovirus causes diarrhea in all age groups ○ Bacterial infections of the gastrointestinal tract (GI) cause the most serious cases of diarrhea ○ Food poisoning is a brief illness that is caused by toxins produced by bacteria ○ With some bacteria (e.g., staphylococcus aureus), toxins are produced in the food before its eaten, while other bacteria (e.g., clostridium perfringens) toxins are produced in the bowel after food is eaten ○ Typically, food contaminated with S. aureus (such as salad, meat, or sandwiches with mayonnaise) has been left at room temperature for 6 hours or more ○ C. perfringens is an example of a bacterium that often multiplies in canned foods ○ Diarrhea-producing bacteria can also invade the small intestine and colon, cause an enterocolitis, and interfere with absorption of fluids in the GI tract tract ○ Campylobacter jejuni is the most common bacterium that causes acute enterocolitis in the US ○ Other bacteria that cause enterocolitis include: Shigella, salmonella, E. coli ○ These bacteria usually are acquired by drinking contaminated water or eating contaminated foods like vegetables, poultry and dairy products ○ Enterocolitis caused by the bacterium Clostridium difficile is unusual because it is often the result of the use of antibiotics ○ C. difficile is also the most common nosocomial (i.e., acquired while in the hospital) infection that causes diarrhea ○ Although many strains of E. coli bacteria are normal inhabitants of the small intestin and colon, some strains cause diarrhea by producing toxins (i.e., enterotoxigenic E. coli, or ETEC) or by invading and inflaming the lining of the GI tract (i.e., enteropathogenic E. coli or EPEC) ○ Travelers diarrhea is usually caused by an ETEC strain ○ Tourists visiting foreign countries with warm climates and poor sanitation (e.g., mexico and parts of Africa) can acquire ETEC by consuming contaminated fruits, vegetables, seafood, raw meat, water and ice cubes ○ Parasitic infections are an occasional cause of acute diarrhea in the United states ○ Infection with giardia lamblia occurs in individuals who hike in the mountains or travel abroad and is transmitted by contaminated drinking water ○ Cryptosporidium is a diarrhea producing parasite that is spread by public swimming pools because it can survive chlorination ○ Cyclospora is a diarrhea-producing parasite that has been associated with contaminated raspberries from Guatemala ○ Many medications cause diarrhea soon after treatment is begun. Medications that most frequently cause diarrhea are antacids and nutritional supplements that contain magnesium ○ Infectious diseases (e.g., G. lamblia and those common to acquired immunodeficiency syndrome (AIDS) e.g., cryptosporidium, cytomegalovirus, and Mycobacterium avium complexa) ○ Bacterial overgrowth of the small intestine (e.g., following acute, viral, bacterial, or parasitic infections) ○ Inflammatory bowel disease (i.e., crohn disease and ulcerative colitis), in which can impair the absorption of water ○ Colon cancer, especially in the distal part of the colon, which can impair the absorption of water, carbohydrate or fat malabsorption ○ Endocrine disease (e.g., hyperthyroidism and addison disease), in which diarrhea is caused by a hormonal imbalance ○ Laxative abuse (e.g., by those trying to lose weight) ○ Congenital and metabolic abnormalities ○ Malabsorption of carbohydrates refers to an inability to digest and absorb carbohydrates ○ The most well-recognized carbohydrate malabsorption condition occurs with lactose deficiency (also known as lactose or milk intolerance) in which milk products containing lactose are the culprits ○ Lactase deficiency occur in three or four non-white adults and in up to one in four white adults ○ With lactase deficiency, lactose cannot be metabolized and absorbed in the intestines ○ As a result, undigested lactose reaches the colon and draws water by osmosis into the colon, causing diarrhea ○ Other sugars in the diet can also cause diarrhea ○ Other sugars in the diet can also cause diarrhea, including fructose and sorbitol  ○ Sorbitol is commonly used as an artificial sweetener in gums, candies, and some medications ○ Malabsorption of fat refers to an inability to digest and absorb lipids ○ Fat malabsorption develops from reduced secretions of pancreatic enzymes that are necessary for normal digestion of lipids (e.g., as in pancreatitis) or from disease of the lining of the small intestine that prevent the absorption of digested fat (e.g., celiac disease) ○ Undigested fat enters the jejunum and colon, where bacteria convert it into chemicals that cause excessive amounts of water to be secreted into the GI tract, causing diarrhea ○ In secretory diarrhea, a pathophysiologic event such as the presence of a bacterial or viral toxin promotes secretions of chloride ion and water into the small intestine while simultaneously interfering with absorption ○ LVD (1 L or more/day) may result from the inappropriate secretion of fluid across the intestinal lining ○ Causes of secretory diarrhea include endotoxins produced by such microbes as vibrio cholerae (the causative agent of cholera), S. aureus, rotavirus, and ETEC Diagnosis ○ Physical examination helps the clinician identify underlying systemic disease ○ Stool culture, examination of stool specimens for blood, abdominal x-rays, and intestinal biopsies provide more specific data ○ With non-inflammatory diarrhea, leukocytes are absent in the feces ○ Watery, non-bloody diarrhea as associated with abdominal cramps, bloating, nausea or vomiting suggest a small intestinal source caused by either toxin-producing bacterium (e.g., ETEC, S. aureus, C. perfringens) or viruses, or Giardia ○ Prominent vomiting suggests viral enteritis or food poisoning caused by S. aureus. LVD resulting in dehydration, hypokalemia, and metabolic acidosis suggests cholera Cholera-induced diarrhea ○ Infection is caused by water contaminated with vibrio cholerae or food prepared with contaminated water ○ The microbes traverse the stomach, enter the small intestine, and propagate ○ Although they do not invade the intestinal mucosa, the microbes produce a potent toxin that causes a massive outpouring of water and electrolytes ○ Severe diarrhea, commonly known as “rice water stool” leads to dehydration and hypovolemic shock Chronic malabsorptive diarrhea (e.g., celiac (+) weight loss, vitamin and mineral deficiencies, disease, bacterial overgrowth, pancreatic increased fecal fat (10 g/day), osmotic diarrhea, insufficiency) hypoalbuminemia  Chronic motility diarrhea (e.g., partial presence of systemic disease or post-abdominal gastrectomy, diabetes mellitus, surgery hyperthyroidism, irritable bowel syndrome) Chronic infectious diarrhea (e.g., resulting (+) stool test for giardia from hiking, camping, antibiotic use, or (+) stool test for C. difficile toxin immunodeficiency) (+) fecal acid fast stain for cyclospora or cryptosporidium ○ As stool leaves the colon, fecal osmolality is equal to serum osmolality, i.e., approximately 290 mosm/kg) Replacement of fluids and electrolytes is considered to be a primary therapeutic goal in the treatment of diarrhea ○ Treatment options for acute diarrhea include: diet, rehydration, the use of antidiarrheal agents and antibiotic therapy ○ Most cases of mild diarrhea will not lead to dehydration provided the patient consumes adequate oral fluids (i.e., oral replacement therapy) containing carbohydrates and electrolytes to replace those lost in diarrheal stool ○ Commonly used beverages, such as apple juice and cola drinks, which have high osmolarity because of their high carb and low electrolyte content are no recommended.