Food Allergies and Intolerances

Food Allergies and Intolerances - Friend or Foe?

⭐ Type I hypersensitivity (IgE-mediated) is the most common mechanism in true food allergies, characterized by rapid onset of symptoms.

• Food Allergy: Immune reaction (IgE/non-IgE mediated) to food components.
• Food Intolerance: Non-immune adverse reaction (e.g., enzyme deficiency, pharmacologic).

Food Allergies and Intolerances - Rogue's Gallery

• Common Allergens:
  • Cow's milk
  • Egg
  • Peanut
  • Wheat
  • Soy
  • Fish
  • Shellfish
  • Tree nuts

• Clinical Manifestations by System:

  System	Manifestations
  Cutaneous	Urticaria, angioedema, atopic dermatitis exacerbation
  GI	Vomiting, diarrhea, abdominal pain, FPIES
  Respiratory	Allergic rhinitis, asthma, laryngeal edema
  Systemic	Anaphylaxis (hypotension, bronchospasm)

⭐ Cow's milk protein allergy is the most common food allergy in infancy and early childhood, often outgrown by age 5.

• Food Protein-Induced Enterocolitis Syndrome (FPIES): Profuse, repetitive vomiting 1-4 hours post-ingestion; lethargy, pallor, diarrhea. Can lead to dehydration, shock. Common triggers: cow's milk, soy, rice, oats. No IgE involvement typically.

Food Allergies and Intolerances - Unmasking Allergies

• Initial Steps: Detailed history (symptoms, timing, suspected foods), physical exam.
• IgE-Mediated Tests:
  • Skin Prick Test (SPT): Wheal ≥3mm > negative control. Positive predictive value varies.
  • Specific IgE (sIgE) blood test: Quantitative; higher levels suggest ↑ likelihood of clinical allergy.
• Elimination Diet: Remove suspected food(s) for 2-4 weeks; monitor symptoms.
• Oral Food Challenge (OFC):
  • Confirms diagnosis after positive tests or supervised reintroduction.

⭐ Double-Blind Placebo-Controlled Food Challenge (DBPCFC) is the gold standard for diagnosing food allergy, though an open Oral Food Challenge (OFC) is often used in clinical practice.

Food Allergies and Intolerances - Dodging & Defusing

• Allergy: IgE-mediated (e.g., nuts, milk). Intolerance: Non-IgE (e.g., lactose).
• Diagnosis: History, SPT, sIgE. OFC (gold standard).
• Anaphylaxis Management:
  • 📌 Epinephrine dose: $0.01 \text{ mg/kg}$ IM (max 0.3mg pre-pubertal, 0.5mg pubertal/adult) anterolateral thigh.
  • 

⭐ Prompt administration of intramuscular epinephrine is the cornerstone of anaphylaxis management and can be life-saving.

• Prevention: Strict dietary avoidance. Written emergency action plan. Educate on EAI use.

Food Allergies and Intolerances - Gut Grumbles

• Food Allergy: IgE-mediated (e.g., urticaria, anaphylaxis) or non-IgE-mediated (e.g., FPIES).
• Food Intolerance: Non-immunologic (e.g., lactose intolerance).

📌 BLAB for lactose intolerance symptoms: Bloating, Loose stools, Abdominal pain, Borborigmi (rumbling).

High‑Yield Points - ⚡ Biggest Takeaways

• Cow's Milk Protein Allergy (CMPA) is the most frequent food allergy in early infancy.
• Distinguish IgE-mediated (rapid onset) from non-IgE-mediated (delayed) reactions.
• Oral Food Challenge (OFC) remains the gold standard for definitive diagnosis.
• Intramuscular epinephrine is the first-line treatment for anaphylaxis.
• Key allergens: milk, egg, soy, wheat, peanuts, tree nuts, fish, shellfish.
• Lactose intolerance (enzyme deficiency) is distinct from CMPA (immune response).
• FPIES causes severe, delayed gastrointestinal symptoms like profuse vomiting_