Immunoglobulin E deficiency: a forgotten clue pointing to possible immunodeficiency?

Area of Science:

• Clinical Immunology
• Laboratory Medicine
• Diagnostic Pathology

Background:

• Primary antibody deficiencies are frequently diagnosed late.
• Very low immunoglobulin E (IgE) levels, detected during allergy investigations, may signal other immunodeficiencies.
• Early identification of immunodeficiency is crucial for patient outcomes.

Purpose of the Study:

• To evaluate the utility of a new laboratory policy for identifying potential antibody deficiencies based on very low IgE levels.
• To assess the diagnostic yield of investigating low IgE in routine patient samples.
• To improve the detection rates of primary antibody deficiencies.

Main Methods:

• Implementation of a laboratory policy to test for linked antibody deficiency in patients with very low IgE.
• Audit of routine laboratory results over a two-year period.
• Analysis of immunoglobulin levels and serum electrophoresis in selected cases.

Main Results:

• Very low IgE (≤2 IU/mL) was detected in 3.2% (85/2622) of routine samples.
• Six patients (2 children, 4 adults) exhibited immunoglobulin levels below age-appropriate reference ranges.
• The laboratory's initiative led to the unsuspected diagnosis of antibody immunodeficiency in two of these six patients.

Conclusions:

• Very low serum IgE levels warrant further investigation, including immunoglobulin quantification and serum electrophoresis.
• Common variable immunodeficiency, a potential cause of adult lung disease, is often overlooked.
• Proactive laboratory screening can facilitate earlier diagnosis of antibody deficiencies.