IgE (Total) Blood Test: Normal Ranges, Causes & What Your Results Mean

What Is IgE (Total)?

Immunoglobulin E (IgE) is one of five classes of antibodies produced by the immune system. While it is present in the lowest concentration of all immunoglobulins in the blood - typically comprising less than 0.001% of total serum immunoglobulins - IgE plays a disproportionately powerful role in allergic reactions and defence against parasitic infections.

When your body encounters an allergen (such as pollen, dust mites, animal dander, or certain foods), specialised immune cells (B lymphocytes) produce IgE antibodies specific to that allergen. These IgE molecules then bind to the surface of mast cells and basophils - immune cells found throughout the body, particularly in the skin, lungs, and gastrointestinal tract. When the allergen is encountered again, it cross-links the bound IgE molecules, triggering the release of histamine and other inflammatory mediators that cause allergic symptoms.

The total IgE blood test measures the overall amount of IgE in your serum, giving an indication of your body's general allergic or atopic tendency. It does not identify which specific allergens you react to - that requires specific IgE testing (formerly known as RAST tests) for individual allergens.

Total IgE is clinically useful because significantly elevated levels point towards allergic disease, atopic conditions, or parasitic infections, while very high levels may suggest more serious conditions such as allergic bronchopulmonary aspergillosis (ABPA) or hyper-IgE syndrome.

Why Is IgE (Total) Tested?

Total IgE testing is requested for several clinical reasons:

• Allergic disease assessment: If you have symptoms suggestive of allergy, such as chronic rhinitis, asthma, eczema, urticaria, or recurrent anaphylaxis, total IgE can help determine whether an allergic (IgE-mediated) mechanism is likely. This guides whether specific allergen testing is warranted.
• Asthma phenotyping: Total IgE levels help classify asthma into allergic (high IgE) and non-allergic subtypes, which has important implications for treatment. Patients with allergic asthma and high IgE may benefit from anti-IgE therapy (omalizumab).
• Omalizumab dosing: If you are being considered for omalizumab (Xolair), a monoclonal antibody that binds free IgE, your total IgE level (along with body weight) determines the appropriate dose and dosing interval. NICE recommends omalizumab for severe persistent allergic asthma that is inadequately controlled on standard therapy.
• Allergic bronchopulmonary aspergillosis (ABPA): A very high total IgE (often exceeding 1,000 kU/L) in a patient with asthma or cystic fibrosis raises suspicion for ABPA, a serious fungal hypersensitivity condition requiring specific treatment.
• Parasitic infection screening: In returning travellers or individuals from endemic regions, elevated total IgE may suggest helminth (worm) infections, which characteristically drive IgE production.
• Primary immunodeficiency assessment: Certain rare immunodeficiency syndromes (such as hyper-IgE syndrome/Job syndrome) are characterised by markedly elevated IgE alongside recurrent infections and skin problems.
• Eczema severity assessment: In atopic dermatitis (eczema), total IgE levels often correlate with disease severity, though they are not used in isolation for diagnosis or management.

Normal Ranges

Total IgE is measured in kilo-units per litre (kU/L) or international units per millilitre (IU/mL) - these are equivalent (1 kU/L = 1 IU/mL). Normal ranges vary with age:

Age Group	Normal Range (kU/L)	Notes
Newborn	< 1.5	Very low at birth; IgE does not cross the placenta
1 – 5 years	< 60	Gradually increases through childhood
6 – 9 years	< 90	Continues to rise
10 – 15 years	< 200	Approaches adult levels
Adults (16+)	< 100	Some laboratories use < 120 or < 150

Important notes on interpretation:

• A normal total IgE does not exclude allergy. Up to 20-30% of individuals with confirmed allergic disease have total IgE within the normal range.
• Conversely, a mildly elevated total IgE does not confirm allergic disease - other causes must be considered.
• Reference ranges vary between laboratories. Always compare your result to the specific range provided.
• Total IgE levels tend to be higher in males than females and in smokers compared with non-smokers.

What Do High IgE Levels Mean?

Elevated total IgE can indicate a range of conditions:

• Allergic rhinitis (hay fever): One of the most common causes of elevated IgE. Allergic sensitisation to pollens, house dust mites, moulds, or animal dander stimulates IgE production.
• Allergic asthma: IgE-mediated inflammation in the airways is the hallmark of allergic asthma. Total IgE is often moderately elevated (100-500 kU/L).
• Atopic dermatitis (eczema): Approximately 80% of patients with atopic eczema have elevated total IgE, sometimes very significantly (exceeding 1,000 kU/L in severe cases).
• Food allergy: IgE-mediated food allergies (to peanuts, tree nuts, milk, eggs, fish, shellfish, wheat, or soya) contribute to elevated total IgE.
• Parasitic infections: Helminth infections (roundworms, hookworms, schistosomiasis, strongyloides) are potent stimulators of IgE production and can produce very high levels, often exceeding 1,000 kU/L.
• Allergic bronchopulmonary aspergillosis (ABPA): Total IgE above 1,000 kU/L in a patient with asthma or cystic fibrosis is a key diagnostic criterion for ABPA. This condition requires antifungal treatment and corticosteroids.
• Hyper-IgE syndrome (Job syndrome): A rare primary immunodeficiency characterised by markedly elevated IgE (often exceeding 2,000 kU/L), recurrent staphylococcal skin abscesses, and pneumonias.
• Churg-Strauss syndrome (EGPA): Eosinophilic granulomatosis with polyangiitis is a rare vasculitis that can cause very high IgE alongside asthma, eosinophilia, and multi-organ involvement.

What Do Low IgE Levels Mean?

Low or undetectable total IgE is less commonly a clinical concern, but can have significance in certain contexts:

• Non-atopic individual: A low total IgE simply reflects the absence of allergic sensitisation or significant IgE-mediated immune activation. This is a normal finding in the majority of the population.
• Common variable immunodeficiency (CVID): Some patients with CVID have low IgE alongside low levels of other immunoglobulin classes (IgG, IgA). This primary immunodeficiency causes recurrent infections, particularly of the respiratory and gastrointestinal tracts.
• Selective IgE deficiency: Rare but described, isolated low IgE may occur without clinical significance. Its association with disease is not well established.
• Medications: Certain immunosuppressive drugs and biological therapies can reduce IgE levels. Omalizumab, paradoxically, increases measured total IgE in the short term (due to prolonged IgE half-life when bound to the drug) but reduces free IgE available to trigger allergic reactions.
• Ageing: IgE levels tend to decline modestly in older adults.
• Non-IgE-mediated conditions: If you have allergy-like symptoms but low total IgE, non-IgE-mediated mechanisms may be responsible. These include food intolerances (which involve different immune pathways or non-immune mechanisms), non-allergic rhinitis, and non-eosinophilic asthma.

How to Improve Your IgE Levels

Managing IgE levels is primarily about controlling the underlying allergic or inflammatory condition rather than targeting IgE itself:

Allergen Avoidance

• Identify your triggers: Specific IgE testing or skin prick testing can identify the allergens driving your symptoms. Once identified, targeted avoidance measures are the first line of treatment.
• House dust mite reduction: Use allergen-proof mattress and pillow covers, wash bedding at 60°C, remove carpets where practical, and maintain low humidity (below 50%).
• Pollen management: Monitor pollen counts, keep windows closed during peak pollen hours, shower and change clothes after outdoor exposure, and use wraparound sunglasses.
• Pet allergen control: If pet allergies are confirmed, keeping pets out of bedrooms and using HEPA air filters can reduce allergen exposure.

Medical Treatment

• Antihistamines: Non-sedating antihistamines (cetirizine, loratadine, fexofenadine) are the first-line treatment for allergic rhinitis and urticaria.
• Inhaled corticosteroids: The cornerstone of allergic asthma management, reducing airway inflammation and indirectly reducing IgE-mediated responses.
• Nasal corticosteroids: For allergic rhinitis, nasal steroid sprays (fluticasone, mometasone) are the most effective treatment.
• Immunotherapy (desensitisation): Allergen-specific immunotherapy (sublingual or subcutaneous) can modulate the immune response over time, shifting the balance from IgE-mediated to IgG4-mediated immunity. NICE recommends it for severe allergic rhinitis and bee/wasp venom allergy.
• Omalizumab (Xolair): For severe allergic asthma uncontrolled by standard therapy, this anti-IgE monoclonal antibody binds free IgE and reduces allergic inflammation.

Lifestyle Measures

• Maintain a healthy diet: A diet rich in fruits, vegetables, omega-3 fatty acids, and antioxidants may support a balanced immune response. Some evidence suggests that the Mediterranean diet is associated with lower allergy prevalence.
• Avoid smoking: Cigarette smoke irritates the airways and can exacerbate allergic conditions. Smoking also independently raises IgE levels.
• Manage stress: Psychological stress can worsen allergic conditions. Stress reduction techniques may help reduce symptom flares.

When Should You Get Tested?

Consider a total IgE test if you experience:

• Chronic nasal congestion, sneezing, or runny nose suggestive of allergic rhinitis
• Recurrent wheezing, breathlessness, or asthma symptoms, particularly if triggered by allergen exposure
• Persistent or severe eczema, especially if it began in childhood
• Recurrent urticaria (hives) or angioedema without a clear cause
• Suspected food allergy (immediate symptoms after eating specific foods)
• Recurrent skin or respiratory infections alongside very high IgE (suggestive of immunodeficiency)
• Travel to tropical or subtropical regions with subsequent eosinophilia (suggestive of parasitic infection)
• Assessment for anti-IgE therapy (omalizumab) candidacy

Your GP or specialist may order total IgE alongside a full blood count (to check for eosinophilia) and specific IgE tests for suspected allergens. For children with recurrent allergic symptoms, early testing can guide management and improve quality of life.

Which Lola Health Tests Include IgE (Total)?

Lola Health offers comprehensive blood testing that includes key immune and inflammatory markers:

• Peak Insights - Our most extensive health panel, including immune markers and a thorough assessment of your overall health.
• Vital Check — A detailed wellness assessment covering essential biomarkers to identify potential immune and inflammatory concerns.
• Core Health — An essential health check covering foundational biomarkers to monitor your overall wellbeing.

All Lola Health tests use venous blood draws performed by qualified phlebotomists for medical-grade accuracy. Results are reviewed by GP-certified professionals and delivered with personalised health recommendations.