3.  Diarrhea -working definition is:  three or more loose or watery stools per day or  definite decrease in consistency and increase in frequency based upon an individual baseline  Acute — ≤14 days in duration  Persistent diarrhea — more than 14 days in duration  Chronic — more than 30 days in duration

4.  One of the five leading causes of death worldwide  Most cases of acute diarrhea are due to infections with viruses and bacteria and are self-limited.  Noninfectious etiologies become more common as the course of the diarrhea persists and becomes chronic.  Noninfectious causes of diarrhea include :  drugs,  food allergies,  primary gastrointestinal diseases such as inflammatory bowel disease, and  other disease states such as thyrotoxicosis and the carcinoid syndrome.

5.  Most cases of acute infectious gastroenteritis are probably viral,  In contrast, bacterial causes are responsible for most cases of severe diarrhea

6.  careful history  Duration of symptoms  Frequency and characteristics of the stool  Complete past medical history (identify immunocompromised host)  Important to ask about recent antibiotic use  A food history may also provide clues to a diagnosis:  Within 6 hr Staphylococcus aureus or Bacillus cereus  Within 8 to 16 hr Clostridium perfringens  More than 16 hr viral or bacterial infection ( enterotoxigenic or enterohemorrhagic E. coli).

7.  Physical examination:  fever, which suggests infection with :  invasive bacteria (Salmonella, Shigella, Campylobacter)  Enteric viruses, or  Cytotoxic organism such as Clostridium difficile or Entamoeba histolytica  Evidence of extracellular volume depletion (eg, decreased skin turgor, orthostatic hypotension

8.  E.coli O157:H7 (Most common)  Less common bacterial causes :  Shigella,  Campylobacter,  Salmonella species

9.  Sensitivity and specificity ranging from 20 to 90 percent  Because of these concerns about test performance, the role of testing for fecal leukocytes has been questioned.  However, the presence of occult blood and fecal leukocytes supports the diagnosis of a bacterial cause of diarrhea Uptoate: we perform this examination in addition to obtaining a bacterial culture in high risk patients.

10.  Lactoferrin is a marker for fecal leukocytes, but its measurement is more precise  sensitivity and specificity ranging from 90 to100 percent in distinguishing inflammatory diarrhea (eg, bacterial colitis or inflammatory bowel disease) from noninflammatory causes (eg, viral colitis, irritable bowel syndrome)

11. low rate of positive stool cultures in most reports (1.5 to 5.6 percent) most infectious causes of acute diarrhea are self-limited it is reasonable to continue symptomatic therapy for several days before considering further evaluation

12. we recommend obtaining stool cultures on initial presentation in the following groups of patients:  Immunocompromised patients, including those infected with HIV  Patients with comorbidities that increase the risk for complications  Patients with more severe, inflammatory diarrhea (including bloody diarrhea)  Patients with underlying inflammatory bowel disease in whom the distinction between a flare and superimposed infection is critical  Some employees, such as food handlers

13.  Persistent diarrhea (associated with Giardia, Cryptosporidium,and Entamoeba histolytica)  Persistent diarrhea with exposure to infants in daycare centers(associated with Giardia and Cryptosporidium)  Diarrhea in a man who has sex with men (MSM) or a patient with AIDS (associated with Giardia and Entamoeba histolytica in the former, and a variety of parasites in the latter).  A community waterborne outbreak (associated with Giardia and Cryptosporidium)  Bloody diarrhea with few or no fecal leukocytes (associated with intestinal amebiasis) Three specimens should be sent on consecutive days (or each specimen separated by at least 24 hours)

14.  Begins with general measures such as hydration and alteration of diet.  Antibiotic therapy is not required in most cases since the illness is usually self-limited.  Oral rehydration solutions:  Oral rehydration solutions were developed following the realization that, in many small bowel diarrheal illnesses, intestinal glucose absorption via sodium-glucose cotransport remains intact.

15.  The composition of the oral rehydration solution (per liter of water) recommended by the World Health Organization consists of:  3.5 g sodium chloride  2.9 g trisodium citrate or 2.5 g sodium bicarbonate  1.5 g potassium chloride  20 g glucose or 40 g sucrose

16.  Those with moderate to severe travelers' diarrhea as characterized by more than four unformed stools daily, fever, blood, pus, or mucus in the stool.  Those with more than eight stools per day  volume depletion  symptoms for more than one week  those in whom hospitalization is being considered  Immunocompromised hosts  Signs and symptoms of bacterial diarrhea such as fever, bloody diarrhea (except for suspected EHEC or C. difficile infection  Presence of occult blood or fecal leukocytes in the stool.

17.  empiric therapy:  An oral fluoroquinolone ( ciprofloxacin 500 mg twice daily, norfloxacin 400 mg twice daily, or levofloxacin 500 mg once daily) for three to five days in the absence of suspected EHEC or fluoroquinolone- resistant campylobacter infection  Azithromycin (500 mg PO once daily for three days) or erythromycin (500 mg PO twice daily for five days) are alternative agents if fluoroquinolone resistance is suspected

18.  The benefit of specific dietary recommendations other than oral hydration has not been well-established in controlled trials.  Adequate nutrition during an episode of acute diarrhea is important to facilitate enterocyte renewal  Boiled starches and cereals (eg, potatoes, noodles, rice, wheat, and oat) with salt are indicated in patients with watery diarrhea;  crackers, bananas, soup, and boiled vegetables may also be consumed  Foods with high fat content should also be avoided  In addition, secondary lactose malabsorption is common following infectious enteritis and may last for several weeks to months. Thus, temporary avoidance of lactose-containing foods may be reasonable

21.  Chronic diarrhea affects approximately 5 percent of the population

22.  The principal causes of diarrhea depend upon the socioeconomic status of the population.  In developing countries, chronic diarrhea is frequently caused by:  chronic bacterial, mycobacterial and parasitic infections, although functional disorders, malabsorption, and inflammatory bowel disease are also common.  In developed countries, common causes are :  irritable bowel syndrome (IBS), inflammatory bowel disease, malabsorption syndromes (such as lactose intolerance and celiac disease), and chronic infections (particularly in patients who are immunocompromised).

23.  Optimal strategies for the evaluation of patients with chronic diarrhea have not been established  Recommendations have been derived mostly from expert opinion and from experience  The selection of specific tests, timing of referral, and the extent to which testing should be performed depend upon an appraisal of the likelihood of a specific diagnosis, the availability of treatment, the severity of symptoms, patient preference, and comorbidities.

24. 1) A clear understanding of what led the patient to complain of diarrhea(eg, consistency or frequency of stools, the presence of urgency or fecal soiling) 2) Stool characteristics (eg, greasy stools that float and are malodorous may suggest fat malabsorption while the presence of visible blood may suggest inflammatory bowel disease) 3) Duration of symptoms, nature of onset (sudden or gradual) 4) Travel history 5) Risk factors for HIV infection 6) Weight loss

25. 7) Whether there is fecal incontinence (which may be confused with diarrhea) 8) Occurrence of diarrhea during fasting or at night (suggesting a secretory diarrhea) 9) Family history of IBD 10) The volume of the diarrhea (eg, voluminous watery diarrhea is more likely to be due to a disorder in the small bowel while small-volume frequent diarrhea is more likely to be due to disorders of the colon) 11) The presence of systemic symptoms, which may indicate inflammatory bowel disease (such as fevers, joint pains, mouth ulcers, eye redness)

26. 12) All medications (including over-the-counter drugs and supplements) 13) A relevant dietary (including possible use of sorbitol- containing products and use of alcohol) 14) Association of symptoms with specific food ingestion (such as dairy products or potential food allergens) 15) A sexual history (anal intercourse is a risk factor for infectious proctitis and promiscuous sexual activity is a risk factor associated with HIV infection) · 16) A history of recurrent bacterial infections (eg, sinusitis, pneumonia),which may indicate a primary immunoglobulin deficiency.

28.  The physical examination rarely provides a specific diagnosis.  However, a number of findings can provide clues These include: 1) findings suggestive of IBD (eg, mouth ulcers, a skin rash, episcleritis, an anal fissure or fistula, 2) the presence of visible or occult blood on digital examination, 3) abdominal masses or abdominal pain

29. 4) evidence of malabsorption (such as wasting, physical signs of anemia, scars indicating prior abdominal surgery) 5) Lymphadenopathy (possibly suggesting HIV infection), 6) Abnormal anal sphincter pressure or reflexes (possibly suggesting fecal incontinence) 7) Palpation of the thyroid and examination for exophthalmos and lid retraction may provide support for a diagnosis of hyperthyroidism.

30.  A large number of tests are available for diagnosing specific causes of diarrhea  There is no firm rule as to what testing should be done.  The history and physical examination may point toward a specific diagnosis for which testing may be indicated

31.  The minimum laboratory evaluation in most patients should include :  a complete blood count and differential,  erythrocyte sedimentation rate,  thyroid function tests,  serum electrolytes,  total protein and albumin,  stool occult blood  most patients require some form of endoscopic evaluation and mucosal biopsy (either sigmoidoscopy, colonoscopy, or sometimes upper endoscopy), depending upon the clinical setting

33.  Another useful way to guide specific testing is to attempt to categorize diarrhea as:  watery diarrhea(secretory or osmotic)  fatty diarrhea  inflammatory diarrhea

35.  continues despite fasting  is associated with stool volumes >1 liter/day  occurs day and night (in contrast to osmotic diarrhea)  Although usually unnecessary, the distinction between an osmotic and a secretory diarrhea can also be established by measuring stool electrolytes and calculating an osmotic gap.

36.  (290 - 2 ({Na+} + {K+})  An osmotic gap of >125 mOsm/kg suggests an osmotic diarrhea  while a gap of <50 mOsm/kg suggests a secretory diarrhea

37. secretory diarrhea may include:  Further testing in patients with secretory diarrhea may include: 1) stool cultures to exclude chronic infection, 2) imaging of the small and large bowel 3) selective testing for secretagogues, such as gastrin or vasoactive intestinal polypeptide

39.  Further testing in patients with osmotic diarrhea may be unnecessary if the osmotic agent can be identified based upon the history.  An example is inadvertent ingestion of sorbitol (such as in sugarless candies) or lactose in patients who have lactose intolerance.  Temporary avoidance of lactose-containing foods can help establish the diagnosis of lactose intolerance in patients who were unaware of the diagnosis.

40.  Testing the stool for laxatives may occasionally be required if laxative abuse is suspected.  Laxative abuse can be suggested by the presence of melanosis coli on sigmoidoscopy or colonoscopy.

42. Inflammatory diarrhea should be suspected in patients with: 1) clinical features suggesting inflammatory bowel disease, 2) clinical features suggesting C. difficile infection 3) those at risk for opportunistic infections such as tuberculosis 4) those with a travel history. 5) Serum markers of acute inflammation (such as the sedimentation rate and C-reactive protein levels 6) fecal leukocytes and Fecal calprotectin

43.  Diagnosis can usually be established by:  sigmoidoscopy or colonoscopy or  by analysis of stool specimens (ie, culture or testing for C. difficile toxin).

45.  Fatty diarrhea (steatorrhea) should be suspected in patients who report greasy, malodorous stools and those who are at risk for fat malabsorption, such as patients with chronic pancreatitis.  A variety of tests can be used to confirm the diagnosis.  Currently, the gold standard for diagnosis of steatorrhea is quantitative estimation of stool fat.

47.  empiric therapy may be warranted in certain situations: ◦ · When comorbidities limit diagnostic evaluation. ◦ · When a diagnosis is strongly suspected.  Examples include a daycare worker who develops diarrhea after a known outbreak of Giardiasis  a patient who develops diarrhea following limited (<100 cm) ileal resection in whom bile acid malabsorption is likely,  a patient with known recurrent bacterial overgrowth,  and an otherwise healthy patient with suspected lactose intolerance

48.  Symptomatic therapy is indicated when the diagnosis has been made but definitive treatment is unavailable.  A variety of medications can help relieve symptoms, including loperamide, anticholinergic agents, and intraluminal adsorbents (such as clays, activated charcoal, bismuth, fiber and bile acid binding resins). THE END