Immunoglobulin A (IgA)

High IgA means increased immunoglobulin A production, often from mucosal immune activation. Causes include recent or chronic infections, inflammatory conditions (e.g., IBD, celiac), liver disease, and autoimmune disorders; less commonly it reflects an IgA monoclonal gammopathy or IgA nephropathy. Interpretation needs clinical correlation: repeat testing, evaluate for infection/autoimmune disease, check liver and urine/protein, and consider specialist referral if unexplained.

IgA stands for immunoglobulin A, an antibody class primarily defending mucosal surfaces (respiratory, gastrointestinal, and urogenital tracts) and circulating in blood. Secretory IgA (sIgA), found in saliva, tears, and breast milk, blocks pathogens from attaching to and penetrating mucous membranes, aiding early-life and mucosal immunity. Two subclasses, IgA1 and IgA2, have slightly different distributions and roles.

Low IgA means reduced mucosal antibody protection, raising risk of recurrent sinopulmonary and gastrointestinal infections. It can be selective IgA deficiency (often asymptomatic) or secondary to drugs, protein loss, malignancy, or immune disease. Consequences include frequent infections, allergies or autoimmune conditions, and rare transfusion reactions. Management involves treating infections, updating vaccinations, specialist assessment, and avoiding IgA‑containing blood products if anti‑IgA antibodies exist.

A positive IgA antibody test shows that IgA-class antibodies to a specific pathogen are present. It usually indicates a mucosal immune response from recent or ongoing infection or past exposure, but timing matters. Results must be interpreted with symptoms, other antibody classes (IgM/IgG), and diagnostic tests because false positives or cross-reactions can occur. Consult a clinician for further evaluation.

Elevated IgA is most commonly seen with IgA‑secreting plasma‑cell disorders: IgA multiple myeloma, IgA‑type monoclonal gammopathy of undetermined significance (MGUS), and solitary plasmacytoma. Certain B‑cell lymphomas and other hematologic malignancies (including some chronic lymphocytic leukemias) can occasionally produce IgA paraproteins. Polyclonal IgA rises usually reflect infections or liver disease rather than cancer.

When to worry about IgA levels? Low IgA is concerning if you have recurrent sinopulmonary or severe infections, chronic diarrhea, poor vaccine responses, allergies, or autoimmune disease—consider immunology referral. High IgA that’s persistently elevated or rising with systemic symptoms (fatigue, weight loss, bone pain, abnormal labs) may signal chronic infection, liver disease, autoimmune disease, or monoclonal gammopathy and warrants repeat testing and specialist evaluation.