What is the recommended amount of a substance to administer for allergy testing to check for a reaction?

Test Dosing for Allergy Testing

For intravenous iron preparations, a test dose of 25 mg should be administered for iron gluconate and iron dextran, while iron sucrose does not require a test dose. 1, 2

Intravenous Iron Test Dosing

Iron Gluconate

• Administer a one-time test dose of 25 mg IV in adults 1
• Dilute in 50 mL of 0.9% sodium chloride and infuse over 60 minutes 1
• If no immediate allergic reaction occurs, subsequent routine doses can be given without additional test doses 1

Iron Dextran

• A test dose of 25 mg is mandatory 2
• Administer as a slow IV bolus and wait 1 hour before giving the main dose 2
• For pediatric patients weighing <10 kg, use 10 mg test dose 1
• For pediatric patients weighing 10-20 kg, use 15 mg test dose 1
• Administer by slow IV push at a rate not exceeding 1.0 mL (50 mg if undiluted) per minute 1

Iron Sucrose

• No test dose is required 2
• Test doses are recommended at physician discretion only if patients have exhibited sensitivities to iron dextran or other IV iron preparations, or have multiple drug allergies 2
• If a test dose is deemed necessary, use 25 mg administered as a slow IV push 2

Oral Food Challenge Testing

Standard IgE-Mediated Food Allergy Testing

Initial challenge doses typically start at 0.1% to 1% of the total challenge food, which equals approximately 8-10 mg of whole food or 1-5 mg of food protein. 1

Specific Food Starting Doses (European Academy Guidelines)

• Peanut: 0.1 mg 1
• Milk: 0.1 mL 1
• Egg: 1 mg 1
• Cod: 5 mg 1
• Wheat: 100 mg 1
• Soy: 1 mg 1
• Shrimp: 5 mg 1
• Hazelnut: 0.1 mg 1

Practical Dosing Protocol

• Total challenge dose equals 8-10 g of dry food, 16-20 g meat/fish, or 100 mL wet food 1
• Administer in gradually increasing increments every 15 minutes 1
• Typical cumulative dosing schedule: 0.1%, 0.5%, 1%, 4%, 10%, 20%, 20% of total food 1

Non-IgE-Mediated Food Protein-Induced Enterocolitis Syndrome

Calculate total dose as 0.15-0.3 g protein/kg body weight, not to exceed 3 g protein or 10 g whole food. 1

• For patients with previous severe reactions, use lower starting dose of 0.06 g protein/kg 1
• Administer gradually in 3 feedings over 45 minutes 1
• If asymptomatic for 4 hours, give second dose (appropriate single-serving amount) followed by 2-3 hours observation 1

Critical Safety Considerations

When to Use Lower Initial Doses

Use lower initial doses (10-100 mg of allergenic food) for high-risk patients: 1

• Past history of food-induced anaphylaxis 1
• Persistent asthma 1
• History of reacting to trace food contaminants 1
• High skin prick test reactions or elevated serum food-IgE values 1

Important Caveats for Iron Test Doses

• Test doses have limited predictive value - they neither minimize reaction severity nor prospectively identify patients at risk for severe reactions to later doses 1
• Most patients who suffer severe acute reactions to iron dextran have successfully received both test doses and multiple therapeutic doses in the past 1
• Anaphylaxis-like reactions occur in fewer than 1% of iron dextran or iron gluconate administrations 1
• Test doses for iron dextran and iron gluconate are not interchangeable 1
• Caution is warranted with every dose of iron dextran administered, regardless of prior test dose results 1

Emergency Preparedness Requirements

• Test doses and subsequent doses must be administered by personnel trained to provide emergency treatment 1
• Immediate access to medications for treating serious allergic reactions is required 1
• Typical emergency medications include IV epinephrine, diphenhydramine, and corticosteroids 1