What is the evaluation and treatment approach for diarrhea?

Evaluation and Management of Diarrhea

Begin with oral rehydration solution (ORS) containing reduced osmolarity (<250 mmol/L) at 50-100 mL/kg over 2-4 hours for mild to moderate dehydration, and reserve diagnostic workup only for severe illness, bloody stools, persistent fever, or immunocompromised patients. 1

Initial Assessment

Grade the severity of diarrhea and assess hydration status immediately:

• Mild dehydration (3-5% fluid deficit): Increased thirst, slightly dry mucous membranes 2
• Moderate dehydration (6-9% fluid deficit): Loss of skin turgor, dry mucous membranes, decreased urine output, rapid deep breathing, prolonged skin retraction time 3, 2
• Severe dehydration (≥10% fluid deficit): Severe lethargy or altered consciousness, prolonged skin tenting, shock - this is a medical emergency 2

Evaluate for inflammatory features: bloody or mucoid stools, persistent fever (>38.5°C), severe cramping, signs of sepsis, neutropenia 4, 1

Identify high-risk patients requiring urgent evaluation: immunocompromised, recent hospitalization, recent international travel, suspected outbreak, age extremes with severe symptoms 1, 5

Diagnostic Testing - When to Order

Most patients do NOT require laboratory workup or stool cultures. 1, 5

Reserve diagnostic investigation for:

• Severe dehydration or illness requiring hospitalization 1, 5
• Bloody or mucoid stools 1, 6
• Persistent fever or signs of sepsis 4, 1
• Immunosuppression or immunosuppressive therapy 1, 7
• Suspected nosocomial infection or outbreak 1, 5
• Symptoms persisting >7 days 6

When testing is indicated, molecular studies are preferred over traditional stool cultures unless an outbreak is suspected. 6

Rehydration Protocol

Mild to Moderate Dehydration (First-Line Treatment)

Administer reduced osmolarity ORS (<250 mmol/L, containing 50-90 mEq/L sodium): 1, 2

• Mild dehydration: 50 mL/kg over 2-4 hours 1, 2
• Moderate dehydration: 100 mL/kg over 2-4 hours 3, 2
• Start with small volumes (one teaspoon) using teaspoon, syringe, or medicine dropper, then gradually increase as tolerated 3
• Commercial formulations: Pedialyte, CeraLyte, Enfalyte/Infalyte 2

Replace ongoing losses during rehydration: 3

• 10 mL/kg ORS for each diarrheal stool 3
• 2 mL/kg ORS for each vomiting episode 3
• For infants <10 kg: 60-120 mL per episode, up to ~500 mL/day 3

Nasogastric administration at 15 mL/kg/hour is an alternative if patient cannot drink but is not in shock. 3

Reassess hydration status after 2-4 hours; if still dehydrated, reestimate fluid deficit and restart rehydration. 3

Severe Dehydration (Medical Emergency)

Immediate intravenous rehydration with isotonic fluids (lactated Ringer's or normal saline): 2

• Administer 20 mL/kg IV boluses until pulse, perfusion, and mental status normalize 2
• Once stabilized, transition to ORS for remaining deficit replacement 2
• Monitor serum osmolarity changes (should not exceed 3 mOsm/kg/h) 2
• In patients with renal or cardiac compromise, monitor closely to avoid fluid overload 2

Nutritional Management

Resume age-appropriate normal diet immediately after or during rehydration - do NOT "rest the bowel." 1, 2

Breastfed infants must continue nursing on demand throughout the illness. 3, 2

Bottle-fed infants should receive full-strength, lactose-free, or lactose-reduced formulas immediately upon rehydration. 3, 2

Children >4-6 months should be offered age-appropriate foods every 3-4 hours as tolerated. 3

Pharmacologic Management

Antidiarrheal Agents

Loperamide may be given to immunocompetent adults with acute watery diarrhea: 1

• Initial dose: 4 mg, then 2 mg every 2-4 hours or after each unformed stool 4
• Maximum daily dose: 16 mg 4

ABSOLUTE CONTRAINDICATIONS for loperamide: 1

• Children <18 years of age 1
• Bloody diarrhea 1
• Fever 1
• Suspected inflammatory diarrhea 1

Alternative opioids (tincture of opium, morphine, codeine) can be used in palliative care settings. 4

Antimicrobial Therapy

In most patients with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is NOT recommended. 1

Exceptions for empiric treatment: 1

• Immunocompromised patients 1
• Ill-appearing young infants 1
• Suspected enteric fever 1

CRITICAL WARNING: Antimicrobial therapy for STEC O157 and other STEC producing Shiga toxin 2 should be AVOIDED due to risk of hemolytic uremic syndrome. 1

Modify or discontinue antimicrobials when a clinically plausible organism is identified. 1

Adjunctive Therapies

Ondansetron may be given to children >4 years and adolescents with vomiting to facilitate oral rehydration tolerance. 1

Probiotic preparations may be offered to reduce symptom severity and duration in immunocompetent patients with infectious or antimicrobial-associated diarrhea. 1

Oral zinc supplementation (20 mg daily for 10-14 days) reduces diarrhea duration in children 6 months to 5 years in areas with high zinc deficiency prevalence or malnutrition. 1

Special Populations

Cancer Patients

Screen for grade of diarrhea using National Cancer Institute Common Toxicity Criteria and assess for potential causes: 4

• Chemotherapy-related (fluorouracil, irinotecan) 4
• Tyrosine kinase inhibitors and biologics (ipilimumab, cetuximab, panitumumab) 4
• Radiation therapy 4
• Infection, antibiotics, dietary changes, fecal impaction 4

Grade 1-2 diarrhea management: 4

• Hydration and electrolyte replacement (oral or IV as appropriate) 4
• Antidiarrheal medications 4
• Bland/BRAT diet (bread, rice, applesauce, toast) 4
• For grade 2: consider anticholinergics (hyoscyamine or atropine) 4

Persistent grade 2 or grades 3-4 diarrhea: 4

• Inpatient treatment 4
• Fluid replacement, antidiarrheal therapy, anticholinergics 4
• Consider octreotide (100-150 mcg SC/IV tid, titrate up to 500 mcg tid or 25-50 mcg/h continuous IV infusion) 4

Uridine triacetate (10 g orally every 6 hours for 20 doses) is indicated for early-onset, severe or life-threatening toxicity including diarrhea within 96 hours following 5-FU or capecitabine. 4

Oral budesonide may be suggested for chemotherapy-induced diarrhea refractory to loperamide, but prophylactic use is not recommended. 4

Neutropenic Enterocolitis

Initial treatment is medical with: 4

• Broad-spectrum antibiotics covering enteric gram-negatives, gram-positives, and anaerobes 4
• Reasonable choices: piperacillin-tazobactam, imipenem-cilastatin, or cefepime/ceftazidime plus metronidazole 4
• G-CSFs, nasogastric decompression, IV fluids, bowel rest 4
• Consider amphotericin if no response to antibacterials (fungemia is common) 4

AVOID anticholinergic, antidiarrheal, and opioid agents as they may aggravate ileus. 4

Clostridioides difficile Infection

Vancomycin 125 mg orally four times daily for 10 days is effective for C. difficile-associated diarrhea, with clinical success rates of 80-81%. 8

Median time to resolution of diarrhea is 4-5 days, with recurrence rates of 18-23% within four weeks after treatment completion. 8

Common Pitfalls to Avoid

Do NOT use antimotility agents as substitute for fluid and electrolyte therapy - they are ancillary only after adequate hydration. 1

Do NOT treat asymptomatic contacts - advise infection control measures instead. 1

Do NOT use commercial sports drinks or juices for rehydration - inappropriate electrolyte composition. 2

Do NOT avoid empiric treatment in persistent watery diarrhea lasting ≥14 days. 1

Do NOT use bile acid sequestrants (cholestyramine, colestipol, colesevelam) routinely - reserve for documented bile salt malabsorption. 4