Approach to Diarrhea

Acute Diarrhea

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

Definitions

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.

Introduction

Most cases of acute infectious gastroenteritis are probably viral,

In contrast, bacterial causes are responsible for most cases of severe diarrhea

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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).

DIAGNOSTIC APPROACH

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

E.coli O157:H7 (Most common)

Less common bacterial causes : Shigella, Campylobacter, Salmonella species

Bloody diarrhea

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.

Fecal leukocytes and occult blood

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)

Lactoferrin

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

When to obtain stool cultures

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

When to obtain stool cultures

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)

When to obtain stool for ova and parasites

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.

TREATMENT

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

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.

When to treat

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

Empiric antibiotic therapy

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

Dietary recommendations

Chronic Diarrhea

Chronic diarrhea affects approximately 5 percent of the population

EPIDEMIOLOGY

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).

ETIOLOGY

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.

EVALUATION

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 history5) Risk factors for HIV infection6) Weight loss

History

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 IBD10) 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)

History

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.

History

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

Physical examination

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.

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

laboratory evaluation

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

laboratory evaluation

Another useful way to guide specific testing is to attempt to categorize diarrhea as:

watery diarrhea(secretory or osmotic)fatty diarrheainflammatory diarrhea

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.

Secretory diarrhea

(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

osmotic gap

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

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.

osmotic diarrhea

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.

Inflammatory diarrhea should be suspected in patients with:

1) clinical features suggesting inflammatory bowel disease,

2) clinical features suggesting C. difficile infection3) those at risk for opportunistic infections such as

tuberculosis4) those with a travel history.5) Serum markers of acute inflammation (such as the

sedimentation rate and C-reactive protein levels6) fecal leukocytes and Fecal calprotectin

Inflammatory diarrhea

Diagnosis can usually be established by:

sigmoidoscopy or colonoscopy or by analysis of stool specimens (ie, culture or

testing for C. difficile toxin).

Inflammatory diarrhea

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.

Fatty diarrhea

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

empiric therapy

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).

Symptomatic therapyTHE END