Can I Be Tested for Atopic Dermatitis?

During the diagnosis process, a dermatologist will conduct a medical history and physical exam to help determine if an individual has atopic dermatitis (AD) or to rule out other conditions. If based on the history and exam there isn't clear evidence of an atopic dermatitis diagnosis a provider may request additional tests. While there are no definitive lab tests that are used to diagnose atopic dermatitis, tests can help to help support the diagnosis of atopic dermatitis or identify other conditions that may be causing symptoms instead.

What tests might a doctor order?

Patch testing

A patch test can be conducted to determine to detect allergic contact dermatitis. During a patch test, the person will have a patch that is covered in allergenic chemicals and is placed on the skin for 48 hours. The patch test can help identify contact allergy to metals (e.g., nickel), rubber, leather, formaldehyde, lanolin, fragrances, etc.

Allergy skin testing

A skin prick test (which may also be called a scratch or puncture test) will check for an immediate allergic reaction. During this test a drop of allergen extract will put placed on the skin, sometimes a small prick will be applied to place the allergen into the skin's surface.

Blood tests

A provider may order a blood test that will look for allergen-specific IgE antibody. A negative test result may help to rule out specific allergies, but a positive test result may only indicate that there is a sensitization. You may require additional information to confirm whether a positive result is clinically relevant or not. Blood tests may also be ordered to see if there are high levels of eosinophils. Eosinophils cells in the blood are part of an immune reaction. Elevated blood eosinophils often occur in people with atopic diseases, including atopic eczema.

Skin biopsy

Sometimes a skin biopsy will be performed. A biopsy is when a provider will numb an area and then remove one or more than one small pieces of skin. A skin biopsy may help rule out other conditions that may present similarly to AD, such as psoriasis or even a low-grade skin cancer.

FLG gene testing

The primary function of the skin is to act as a barrier that restricts water loss and prevents the entry of irritants, allergens, and pathogens. The outermost layer of the skin (the corneal layer) contains a protein filaggrin that plays a key role in the skin's structure and formation.

The gene that codes for this protein is called FLG, and researchers have identified more than 40 mutations in this gene that have been associated with about half of patients with moderate to severe AD. Not all people with FLG mutations will develop AD and not all people with AD have the FLG mutation, nonetheless, a filaggrin deficiency has been described as something that may contribute to the pathogenesis of atopic dermatitis.

Experiences with diagnostic tests

In our In America Atopic Dermatitis 2017 survey we asked participants about their experiences getting diagnosed with atopic dermatitis, specifically, we asked what tests they had performed during the diagnostic process. Half of the survey respondents had diagnostic testing done, with almost two-thirds of respondents having skin patch testing conducted. A look at participants responses to our survey questions about diagnostic testing. Testing for the FLG mutation may be used for risk assessment for atopic diseases.

"During your diagnosis process were any of the following tests conducted?"

• 64% of respondents had skin patch testing
• 55% of respondents had an allergy prick or intradermal testing done
• 46% of respondents had a skin biopsy
• 32% of respondents had blood tests performed

"Do you have the filaggrin (FLG) genetic mutation?"

• 98% had not been tested for the FLG genetic mutation or were unsure if they've been tested
• 1% had tested positive for the FLG genetic mutation

When you were diagnosed with atopic dermatitis did you have any testing done? Have you had the genetic testing for the FLG mutation? Share your diagnosis story with the community.