When and how to address significantly elevated IgE levels in food allergy

Total serum immunoglobulin E (tIgE) levels and food specific IgE (sIgE) are frequently ordered during atopic evaluation. Significantly elevated immunoglobulin E (IgE) levels (typically >1000 IU/mL) warrant careful consideration because this may influence the differential diagnosis, prognostic assessment, disease severity, and therapeutic approach in food allergy. High tIgE levels, along with specific “red flags” (e.g., severe, multiorgan, refractory atopic disease; recurrent infections; autoimmunity; or positive family history) that may prompt consideration of a group of inborn errors of immunity known as primary atopic disorders (PAD). These patients may benefit from targeted therapies such as dupilumab, Janus kinase inhibitors, or hematopoietic stem cell transplantation, which can meaningfully alter disease trajectory when initiated early. Importantly, increased use of potent therapies may shift definitions of refractory or severe atopic disease, which makes patients with PADs potentially harder to identify. Very elevated tIgE levels also impact biologic dosing thresholds, potentially limiting access to IgE-targeted therapies and underscoring the need for IgE-independent dosing strategies. Although elevated sIgE levels are more predictive of allergy likelihood, they do not reliably indicate reaction severity or threshold. The sIgE:tIgE ratio may enhance predictive value, particularly in accelerated oral immunotherapy protocols that involve omalizumab, in which baseline ratios may correlate with early reactions and treatment response. This narrative review summarizes the relevant evidence for these considerations on how to address elevated tIgE and sIgE levels in food allergy to aid in diagnosis, risk stratification, and treatment planning.