The patient is probably having a delayed allergenic response to an indoor mold allergen. Early reactions can occur immediately following allergen inhalation but can also manifest 4-10 hours after exposure to wet and damp areas, such as bathrooms and basements.
Allergic asthma represents the most common asthma phenotype. The average age of onset is younger than that of nonallergic asthma, with allergens triggering exacerbations in 60%-90% of children compared with 50% of adults. Triggers can include mold spores, seasonal pollen, dust mites, and animal allergens. There is also an increased incidence of co-occurring allergic rhinoconjunctivitis and atopic dermatitis in patients with allergic asthma.
During an acute asthma exacerbation, lung examination findings may include wheezing, rhonchi, hyperinflation, or a prolonged expiratory phase. In children, supraclavicular and intercostal retractions and nasal flaring, as well as abdominal breathing, are particularly telling. Total serum immunoglobulin E levels are usually higher in allergic vs nonallergic asthma (> 100 IU), although this marker is not specific to asthma.
The allergic asthma phenotype usually responds to inhaled corticosteroid therapy. Although evidence suggests that allergic vs nonallergic asthma is less severe in many cases, compelling data point to a causal relationship between mold allergy and asthma severity in a subgroup of younger asthma patients; specifically, mold sensitization may be associated with asthma attacks requiring hospital admission in this population.
Although spirometry assessments should be obtained as the primary test to establish the asthma diagnosis, to test for allergic sensitivity to specific allergens in the environment, allergy skin tests and blood radioallergosorbent tests may be used. Up to 85% of patients with asthma demonstrate positive skin test results, and in children, this sensitization is reflective of disease activity. Such testing for allergen-specific immunoglobulin E is critical in prescribing allergen avoidance techniques and allergen immunotherapy regimens, although the method shows a relatively high false positive rate and should not be performed during an exacerbation.
Zab Mosenifar, MD, Medical Director, Women's Lung Institute; Executive Vice Chairman, Department of Medicine, Cedars Sinai Medical Center, Los Angeles, California.
Zab Mosenifar, MD, has disclosed no relevant financial relationships.