Makindo Medical Notes

🤧 Allergic disorders are conditions caused by an exaggerated immune response to normally harmless substances called allergens. They are highly prevalent worldwide and account for a major burden of chronic disease, especially in children and young adults. Reactions can be mild (hay fever, eczema) or severe and life-threatening (anaphylaxis). Early recognition, prevention, and appropriate management are crucial. 🚨

🧬 Physiology & Pathophysiology of Allergy

• Immune sensitisation: On first exposure, allergens are processed by antigen-presenting cells and presented to Th2 helper T cells, which release cytokines (IL-4, IL-5, IL-13).
• IgE production: B cells switch to produce allergen-specific IgE antibodies under Th2 influence. These IgE molecules bind to mast cells and basophils.
• Re-exposure: When the allergen is encountered again, it cross-links IgE on mast cells → degranulation.
• Mediators released: Histamine, leukotrienes, prostaglandins, and cytokines → cause vasodilation, increased vascular permeability, smooth muscle contraction, and mucus secretion.
• Clinical outcomes: Sneezing, wheezing, itching, urticaria, angioedema, or systemic anaphylaxis depending on the site and severity of reaction.

💡 In essence: Allergy = IgE + mast cell activation. Repeated exposure = more vigorous response → chronic inflammation (e.g. asthma, eczema).

🌿 Common Types of Allergic Disorders

🔍 Diagnostic Approach

• 🩹 Skin Prick Tests: Immediate hypersensitivity testing.
• 🧪 IgE Blood Tests: Specific allergen IgE levels.
• 🥗 Elimination Diets: For food allergy confirmation.
• ⚠️ Challenge Tests: Under medical supervision only.

💊 Treatment & Management

• 🚫 Avoidance: Best prevention strategy.
• 💊 Medications: Antihistamines, corticosteroids, leukotriene inhibitors.
• 💉 Immunotherapy: Gradual desensitisation (allergy shots or tablets).
• ⚡ Epinephrine: First-line for anaphylaxis, must be carried by high-risk patients.

🚨 Red Flags

• ⚡ Anaphylaxis: Immediate epinephrine and 999 call.
• 😮‍💨 Severe asthma attack: Not relieved by inhalers → urgent hospital care.
• 📈 Sudden worsening symptoms: New or rapidly progressing → emergency review.

✅ Summary: Allergies result from IgE-mediated immune overreaction. They range from mild rhinitis to life-threatening anaphylaxis. Medical students should understand both mechanisms and clinical presentations, as prompt recognition and treatment save lives.