Low immunoglobulin A levels detected via the tissue transglutaminase assay can reveal previously undetected monoclonal proteins.

Increased awareness of coeliac disease and the 2009 NICE guidance has led to an increase in patients being screened for Immunoglobulin A deficiency. We have shown previously that this provides an opportunity for the early identification of other underlying primary immunodeficiency, e.g. common variable immunodeficiency. In this context, the underlying gastrointestinal problem appears to be related to bacterial overgrowth. Here, we demonstrate that in addition this also provides an opportunity to reveal underlying secondary immunodeficiency due to other causes in patients with gastrointestinal presentation, notably lymphoproliferative disorders. In one 3-month period, of 60 cases reviewed for low Immunoglobulin A, we found four new paraproteins through this testing route; one symptomatic multiple myeloma, one asymptomatic multiple myeloma, one monoclonal gammopathy of uncertain significance and one in a known chronic lymphocytic leukaemia patient.