Urinary Biopyrrin is a Biomarker for Atopic Dermatitis Severity

Urine Biopyrrin Correlates with Eczema Activity

Urinary biopyrrin is a marker for severe eczema.

What is Atopic Dermatitis?

Atopic dermatitis is a chronic inflammatory skin disease that causes severe itching, and results in eczematous skin lesions at the sites of scratching. Atopic dermatitis, along with food allergies, is often the first manifestation of allergic disease in young children. The pattern of the eczema rash differs depending on the age of the person affected: Infants tend to rub their cheeks against their shoulders, scratch their chests and rub the backs of their heads against the bed, while older children and adults tend to scratch in flexural areas, such as the inside of the elbows and behind the knees.

Generally speaking, three criteria are required in order to make a diagnosis of atopic dermatitis. First, there must be itching present. If a person doesn’t have itching, he or she cannot have atopic dermatitis. Second, there must be a rash present. The rash occurs as a result of scratching, but will have different appearances depending on how long the rash has been present. With acute atopic dermatitis, there are often blisters (vesicles) with clear fluid present. Bleeding may occur as a result of severe scratching. As the rash becomes more chronic, the skin may look rough, thickened and have a leathery appearance (lichenification). The last criterion that needs to be met is that the person must be atopic. Atopic refers to the characteristic of being allergic, although it is not uncommon for people with atopic dermatitis to not show allergies on allergy skin testing. These people may make allergic antibodies against proteins in their own body.

What Triggers Atopic Dermatitis?

Food allergies and contact aeroallergens (such as pet dander and dust mites), are common triggers for atopic dermatitis. Irritants and dry weather can also worsen symptoms. People with atopic dermatitis may also have a flare in their symptoms due to an infection caused by bacteria, fungi or viruses.

It can be difficult to predict when a flare of atopic dermatitis may occur, but once itching has become severe and scratching occurs, it can be difficult to get symptoms under control. There is a need for a biomarker for atopic dermatitis that can be followed to predict exacerbations of atopic dermatitis.

Is It Possible to Predict Flares of Atopic Dermatitis?

Recently, a group of researchers from Japan discovered an association between urinary biopyrrin and atopic dermatitis severity. Biopyrrin, a metabolite of bilirubin, is excreted in the urine, and is a marker of inflammation in the body. Urinary biopyrrin has been previously shown to be elevated in people with heart disease, asthma and extreme physical exercise. In the study published in 2014, Japanese researchers showed that the level of urinary biopyrrin correlated with the severity of atopic dermatitis – the people with the worst atopic dermatitis had the highest levels of urinary biopyrrin, while people with moderate atopic dermatitis had medium levels of urinary biopyrrin, and healthy people and people with mild atopic dermatitis had low levels of urinary biopyrrin.

Urinary biopyrrin may represent a biomarker for atopic dermatitis that could help predict exacerbations before they occur, so that appropriate treatments can be started in order to prevent severe attacks. Such treatments may include increasing bathing, moisturizing, and using higher potency topical corticosteroids. By following urinary biopyrrin levels, people suffering from atopic dermatitis may have better control of their symptoms, have a better quality of life, and avoid the need for systemic corticosteroids that could cause severe side effects.

Learn all about atopic dermatitis.


Chiba T, Tatematsu S, Nakao M, Furue M. Urinary Biopyrrin: A Potential Inflammatory Marker of Atopic Dermatitis. Ann Allergy Asthma Immunol. 2014;112:182-3.

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