What does the Aspergillus fumigatus IgE test measure?

Why is Aspergillus fumigatus IgE measured?

Detection of Aspergillus fumigatus-specific IgE confirms type-I sensitisation and is a cornerstone of diagnosing allergic bronchopulmonary aspergillosis (ABPA), a Th2-driven pulmonary syndrome that complicates asthma and cystic fibrosis. Sensitisation also contributes to severe asthma with fungal sensitisation and may be implicated in allergic rhinitis or hypersensitivity pneumonitis when occupational or environmental exposure is high. A positive result indicates immune recognition but does not by itself establish disease; clinical correlation with symptoms, imaging, and pulmonary function is essential.

Reference ranges

Standard reference

<0.35 kU/L is considered negative; 0.35–0.69 kU/L equivocal (class 1); ≥0.70 kU/L positive (classes 2–6), with higher classes reflecting greater sensitisation.

Functional medicine optimal

Undetectable (<0.35 kU/L). Titres ≥0.70 kU/L confirm sensitisation; ABPA typically produces markedly elevated total IgE and Aspergillus-specific IgE, whereas simple sensitisation may show low-positive titres.

Units

kU/L, IU/mL

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.