Testing immunoglobulin levels after a bronchiectasis diagnosis helps uncover potential immune deficiencies that could be contributing to the condition. Bronchiectasis involves chronic airway damage, often linked to recurrent infections, inflammation, or underlying immune issues. Immunoglobulins (like IgG, IgA, IgM, and sometimes IgE) are antibodies critical for fighting infections, particularly in the respiratory tract. Low levels might explain why someone’s getting frequent lung infections, which can drive the cycle of airway damage in bronchiectasis.

For example, conditions like Common Variable Immunodeficiency (CVID) or specific antibody deficiencies are associated with low immunoglobulin levels and can present with bronchiectasis. In CVID, bronchiectasis shows up in about 20-30% of cases due to repeated infections. IgG subclass deficiencies or low IgA (common in selective IgA deficiency) can also predispose someone to chronic respiratory issues. Testing helps confirm if these are factors.

It’s also practical: if levels are low, treatments like immunoglobulin replacement therapy could reduce infection rates and slow disease progression. On the flip side, normal or high levels might point to other causes, like allergic bronchopulmonary aspergillosis (linked to elevated IgE) or autoimmune issues. Either way, it’s about pinning down the root cause to guide treatment, not just treating the bronchiectasis in isolation. If the patient’s history screams recurrent sinus or lung infections, this step’s even more critical.