Written Summary: Pediatrics, 57:02 - DIARRHEA/PEANUT ALLERGY

Main Written Summaries Listing | Pediatrics: 2011 Listings

Volume 57, Issue 02

January 21, 2011

The following is an abstracted summary, not a verbatim transcript, of the lectures/discussions on this audio program. If, after reviewing this written summary, you would like to hear the contents and/or earn CME/CE credit, simply visit the Audio-Digest Foundation website

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Diarrhea/Peanut Allergy

Educational Objectives

The goal of this program is to improve the diagnosis and management of pediatric diarrhea and peanut allergy. After hearing and assimilating this program, the clinician will be better able to:

1. Determine whether diarrhea is osmotic or secretory.

2. Differentiate between infectious, malabsorptive, immune-mediated, and inflammatory-mediated causes of pediatric diarrhea.

3. Recommend appropriate therapy for children with diarrhea based on patient history and diagnostic testing.

4. Identify patients for whom injectable epinephrine should be prescribed.

5. Utilize IgE testing to diagnose food allergies in appropriate candidates.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty members to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the following has been disclosed: Dr. Burks is a consultant for ActoGeniX NV, Intelliject, McNeil Nutritionals, Novartis, and Schering-Plough, owns stock in Allertein Therapeutics and Mast Cell Pharmaecuticals, is on the advisory board for Dannon Company Probiotics, and has served on an expert panel for Nutricia. Dr. Cochran and the planning committee reported nothing to disclose.

Diarrhea: Acute and Chronic

William J. Cochran, MD, Clinical Professor of Pediatrics, Temple University School of Medicine, Philadelphia, PA, and Vice Chair, Department of Pediatrics, Geisinger Clinic, Danville, PA

Overview: most common cause of morbidity and mortality in children (causes >2 million pediatric deaths per year worldwide and 500 pediatric deaths per year in United States); second most common cause of pediatric visits

Definition: defined as change in stool consistency (usually mushy, loose, or watery); normal volume typically 10 mL/kg per day in children, 200 g/day in teenagers and adults; diarrhea associated with change in frequency (normal frequency varies by age and among individuals; size and consistency of stool often more informative); acute diarrhea — <2 wk in duration; chronic diarrhea — >2 wk in duration

Types: osmotic diarrhea — results from malabsorption of nutrients; confirmed when nothing-by-mouth status arrests diarrhea; fecal electrolyte analysis reveals stool sodium <40 mEq/L; measure fecal osmotic gap by multiplying sum of sodium and potassium by 2 and subtracting this number from 200 mmol (value >50 indicates osmotic diarrhea); lactose intolerance represents classic cause; secretory diarrhea — characterized by persistent diarrhea in nothing-by-mouth state, normal fecal osmotic gap, and markedly increased fecal sodium levels (>70 mEq/L); cholera represents classic infectious cause

Etiology

Infection: primary cause of acute diarrhea; largely viral, but can also be bacterial or parasitic; bacterial causes of chronic diarrhea — Campylobacter, Yersinia, Aeromonas, and Clostridium difficile most common; postenteritis syndrome — occurs after acute gastroenteritis with damage to small bowel, resulting in malabsorption (particularly of lactose)

Malabsorption of carbohydrates: congenital glucose and lactose malabsorption (rare) presents with profuse watery diarrhea regardless of diet; congenital lactase deficiency also rare; primary lactose intolerance — caused by genetically predetermined decrease in lactase with age (after first year of life); secondary lactose intolerance —caused by acute insult (eg, viral gastroenteritis); recovery occurs in 80% of cases within 1 mo; other sugars — sucrose; fructose; sorbitol

Malabsorption of fats: cystic fibrosis — may present in infants with chronic diarrhea; Schwachman-Diamond syndrome — less common; associated with pancreatic insufficiency, cyclic neutropenia, and lytic lesions in bones; lipase or colipase deficiency — rare; celiac and Crohn disease — cause malabsorption and pancreatic insufficiency; malnourishment — results in decreased pancreatic exocrine function (improves over time)

Immune-mediated diarrhea: non-IgE-mediated food allergy —can present as bloody diarrhea; IgE-mediated processes —can cause chronic diarrhea with malnutrition due to patchy villous atrophy of small bowel; eosinophilic gastroenteritis — causes elevated IgE (in 70% of cases) and peripheral eosinophilia; celiac disease — only immune disorder with known trigger (ie, gluten) and dietary treatment

Inflammatory: Crohn disease; ulcerative colitis

Other: medications; laxative abuse; Munchausen syndrome; excessive intake of fluids or carbohydrates; overly high osmotic load (eg, during tubal feeding of baby formula); motility disorders resulting in overgrowth of bacteria in small bowel

Case 1: 8-mo-old previously healthy child developed fever and vomiting, followed by diarrhea (4-6 nonbloody watery stools per day); voiding normally; case describes acute osmotic diarrhea (secretory ruled out by normal voiding), with infectious or malabsorptive etiology; further evaluation not warranted (based on relative good health and voiding); clear liquids and bananas, rice, applesauce, and toast (BRAT) diet not recommended because diarrhea not excessive and gut requires nutrients to heal; American Academy of Pediatrics (AAP) recommends continuation of cow’s milk formula and adequate hydration; more profuse diarrhea may necessitate change to soy or lactose-free formula

Case 2

Initial presentation: 2-mo-old full-term breast-fed infant with diarrhea (mushy-to-loose stools, 3-4 times per day) for 2 to 3 wk; stool now streaked with bright red blood; previous medication includes amoxicillin 3 wk before for otitis media; behavior, growth rate, and voiding normal; case describes chronic diarrhea that could be infectious, malabsorptive, immune-mediated, or inflammatory-mediated; further evaluation could include culture for C difficile (however, £50% of infants at this age positive for C difficile without associated symptoms) and complete blood cell count (CBC); culture done and results positive for C difficile; acceptable treatment options include metronidazole (eg, Flagyl), fiber supplement (to change pH of stool), probiotics (eg, Florastor with Saccharomyces boulardii), or reassurance of mother; diarrhea persists despite metronidazole; options include placing mother on milk-free diet or placing infant on extensively hydrolyzed protein formula; soy and partially hydrolyzed whey formulas not recommended (not sufficient for children with milk allergies); mother adheres to milk-free diet, without change in infant’s diarrhea; treatment with extensively hydrolyzed protein formula initially resolves diarrhea (recommended for first year of life; allergy usually resolves by 1 yr of age)

Two weeks later: persistent symptoms necessitate colonoscopy; allergic enterocolitis diagnosed; infant responds well to change to amino acid formula; at 6 mo, high cost of formula prompts challenge with different formula (must be performed in office due to »5% chance of shock); speaker challenges with 1 oz of formula, followed by 1 to 1.5 hr of observation

Long-term follow-up: challenge with extensively hydrolyzed formula successful at 6 mo; challenge with milk successful at 1 yr; development of allergic enterocolitis in subsequent children — risk 20% to 40% (>50% with family history); to reduce risk, encourage breastfeeding or use of partially hydrolyzed whey or extensively hydrolyzed casein formula (giving mother probiotics [eg, Lactobacillus rhamnosus GG] in last trimester also helpful); in utero dietary restrictions not effective

Case 3: 3-year-old boy develops low-grade fever, right lower quadrant abdominal pain, and diarrhea; belly pain and diarrhea persist 3 wk later; case describes chronic diarrhea with possible inflammatory-mediated, infectious, malabsorptive, or immune-mediated cause; further evaluation —rectal examination; CBC; erythrocyte sedimentation rate; IgA level; tissue transglutaminase (test deamidated antigliadin antibodies in children <2 yr of age); infectious work-up; lactose intolerance breath test; treatment of child positive for lactose intolerance — speaker does not recommend lactose-free diets (impractical due to ubiquitous presence in foods; dairy products important for calcium intake); lactase supplement (eg, LactAid) at every meal effective; speaker prefers once daily probiotic plus lactase product (Digestive Advantage); infectious cause — stool culture most likely to yield Yersinia

Peanut Allergy

A. Wesley Burks, MD, Kiser-Arena Professor of Pediatrics, and Chief, Division of Pediatric Allergy and Immunology, Duke University Medical Center, Durham, NC

Patient history (1): 19-yr-old woman ingested Rice Krispies treat and experienced immediate itching in throat, hives on face and neck, coughing, wheezing, and feeling of impending doom; paramedics summoned; patient vomited and had respiratory arrest; patient intubated on site and subsequently recovered in hospital; patient’s birth history normal; mother has asthma and allergic rhinitis (only immediate family relevant to allergic conditions); patient breast-fed for 4 mo and had mild atopic dermatitis (AD); she developed hives on face, neck, and upper trunk at 1 yr of age when eating pancakes for first time (resolved in »1 hr)

Lessons learned: 40% to 50% of moderate-to-severe AD in first several years of life triggered (but not caused) by food allergy; evaluate IgE to determine which foods trigger disease; avoidance of foods improves symptoms, but does not cure disease; 8 foods cause 95% of allergic reactions in United States; 5 foods (milk, eggs, peanut, wheat, and soy) trigger most AD and allergic reactions in young children; milk, egg, and peanut cause »80% of adverse food reactions; reactions to wheat and soy decrease, and reactions to fish, shellfish, and tree nuts increase with age; three-quarters of children with AD and food allergy go on to develop allergic rhinitis and half develop asthma; 6% to 8% of children <5 yr of age (4% of children and adults overall) have food allergy; prevalence of peanut allergy in young children doubled in past 20 yr; one-third of families believe they have food allergies

Patient history (2): patient experienced generalized hives, itching, rash, coughing, and wheezing upon eating peanut butter at age 2; patient given diphenhydramine (Benadryl), and symptoms resolved in »1 hr; primary care physician (PCP) performed peanut allergy test, which revealed IgE antibody to peanut of 22 kU/L; patient referred to pediatric allergist and had positive skin-prick testing for peanut and egg; patient provided with injectable epinephrine-containing compound (EpiPen)

Lessons learned: study of 5-yr-old children revealed prevalence of sensitivity to peanuts tripled and likelihood of disease doubled between late 1980s and late 1990s; patients presenting to PCP or allergist at earlier age (average 24 mo of age 10 yr ago vs 12-15 mo of age today); overall understanding of risk for future systemic reaction increasing; provide epinephrine for — all individuals with previous significant systemic reactions to any food; those with peanut, tree nut, fish, and shellfish allergies (at risk for future systemic reaction); those with moderate to severe asthma; at-risk group for food allergy-related mortality — adolescents and young adults with asthma and allergy to peanuts, tree nuts, fish, or shellfish

Biology and pathophysiology: term “allergy” indicates immune-mediated response; primarily IgE-mediated, but eosinophil-associated responses and food protein-induced enterocolitis syndrome (FPIES) can occur; FPIES associated with gastrointestinal (GI) symptoms only (vs GI, skin, and respiratory symptoms in IgE-mediated allergy); sensitization — exposure and subsequent generation of allergen-specific IgE on mast cells in skin, GI tract, and respiratory tract; can occur without clinical disease (ie, presence of symptoms); food ingestion results in aggregation of IgE and release of immediate mediators (histamine and tryptase) and delayed mediators (can cause late-phase response several hours later despite treatment)

Diagnosis: can assess for IgE levels with skin or blood test; tests have excellent negative predictive value; positive skin tests (3 mm greater than negative control) have predictive value of »50%; 3 in vitro tests available in United States with similar sensitivities and specificities and good coefficients of variation; consider clinical history when determining relevance of allergen-specific IgE

General treatment principles: avoid allergen, if possible; as IgE response applies to food protein, avoidance of, eg, peanut oil, unnecessary (contains no peanut protein); provide medical therapy upon reaction; immunotherapy ineffective against food allergy; rely heavily on patient history for diagnosis; consultation with nutritionist important for education of family; refer parents to Food Allergy and Anaphylaxis Network (FAAN, www.foodallergy.org)

Patient history (3): at 5 yr of age, patient ingests cookie recently in contact with peanuts and develops throat symptoms, hives, and wheezing; symptoms resolve with administration of epinephrine injection and diphen-hydramine

Lessons learned: »15% of families have ³1 accidental reaction per year; advise families to anticipate potential reactions (have plan of action), but not expect them; peanut allergies outgrown in »20% of children diagnosed between 1 and 2 yr of age (usually those with lower IgE levels and milder symptoms); allergies to milk, eggs, wheat, and soy often outgrown later in life (12-14 yr of age); reactions primarily occur upon ingestion; generally not caused by touch or inhalation (small risk while on airplanes due to recirculated air)

Patient history (4): aforementioned reaction at age 19 caused by peanut butter included in Rice Krispies recipe; failure to administer epinephrine resulted in escalation of symptoms

Lessons learned: studies ongoing to identify and predict those at increased risk for reaction; diameter of skin test response and level of IgE do not correlate with severity of future reactions; severity of reactions likely to remain consistent (ie, do not escalate with each exposure)

Novel therapies: several anticipated over next 5 yr; accurate diagnostic testing and follow-up considered best treatment at present; anti-IgE therapy being studied as possible adjunct to treatment; Chinese herbal medicines appear promising; allergen-specific immunotherapies derived from food proteins under development; sublingual and oral immunotherapies in preliminary clinical trials

Acknowledgements

Dr. Cochran spoke at 6th Annual Dermatology and Pediatric Topics for Primary Care Practitioners, held July 12-16, 2010, in Hilton Head Island, SC, and sponsored by Geisinger Health System. To attend the next Dermatology and Pediatric Topics for Primary Care Practitioners, visit www.geisinger.org/professional/education/cme. Dr. Burks spoke at Cape Cod Conference on Pediatrics for the Primary Care Physician, presented August 6-8, 2010, in Hyannis, MA, and sponsored by Nemours. To attend the 2011 Cape Cod Conference on Pediatrics for the Primary Care Physician, visit www.PedsEducation.org. The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.