Is a patient with an IgE (Immunoglobulin E) peanut level less than 0.10 considered allergic to peanuts?

Peanut Allergy Assessment with IgE Level Less Than 0.10

A patient with an IgE peanut level less than 0.10 kUA/L is not allergic to peanuts, as this value indicates a strong negative predictive value for peanut allergy. 1

Interpretation of Low Peanut-Specific IgE Levels

• Peanut-specific IgE less than 0.35 kUA/L has a strong negative predictive value for the diagnosis of peanut allergy, with levels below 0.10 kUA/L providing even stronger evidence against allergy 1
• According to the National Institute of Allergy and Infectious Diseases (NIAID) guidelines, the risk of experiencing an allergic reaction is low when IgE levels are less than 0.35 kUA/L 1
• In infants whose IgE level is less than 0.35 kUA/L, peanuts can be safely introduced at home due to the low likelihood of reaction 1

Clinical Significance of Low IgE Levels

• When diagnosing peanut allergy via peanut-specific IgE, a level less than 0.35 kUA/L makes this test beneficial in certain clinical settings (e.g., family medicine, pediatrics) to avoid unnecessary specialist referrals 1
• Patients with undetectable serum food-specific IgE antibodies have been reported to have objective reactions confirmed by oral food challenge, but this is rare 1
• The NIAID expert panel recommends that when peanut-specific IgE is <0.35 kUA/L, peanut should be introduced in the diet soon thereafter, indicating the safety of consumption 1

Risk Assessment Based on IgE Levels

• In the LEAP (Learning Early About Peanut) trial, infants with no detectable IgE to peanut who received a baseline oral peanut challenge had an extremely low rate of reactions (only 1 out of 272 infants had a mild reaction) 1
• The NIAID guidelines categorize patients with peanut-specific IgE <0.35 kUA/L as "sIgE Category A" with recommendation for peanut introduction without further testing 1
• Swedish research indicates that subjects without detectable IgE to major peanut allergens (Ara h 1,2, or 3) consistently had low peanut-specific IgE levels (<10 kUA/L) and were less likely to experience severe reactions 2

Clinical Management Implications

• For patients with peanut-specific IgE <0.10 kUA/L, no special precautions are needed for peanut consumption 1
• In contrast to patients with low IgE levels, those with higher levels (particularly to Ara h 1,2, or 3) have increased risk of respiratory distress and severe reactions 2
• Peanut allergy is typically lifelong and potentially fatal, but this concern does not apply to patients with IgE levels below the detection threshold 3

Important Caveats

• In rare cases, patients may be predominantly sensitized to less common peanut components (like Ara h 6) while having low levels of IgE to Ara h 2, though this is extremely uncommon with IgE levels as low as 0.10 kUA/L 4
• Laboratory test results should always be interpreted in the context of clinical history; a recent anaphylactic reaction would warrant caution despite low test values 1
• Airborne peanut reactions are rare even in confirmed peanut-allergic individuals and cannot be predicted by IgE levels 5