Secretory Piece and IgA Deficiency in a Patient with Waldenstrom's Macroglobulinemia

: A case of a patient suffering from Waldenstrom's macroglobulinemia who developed diarrhea and mild steatorrhea is described. Laboratory studies revealed low serum IgA, intestinal secretory IgA deficiency, and small intestine bacterial overgrowth as demonstrated by the C14-cholylglycine breath test. These findings suggest that selective IgA deficiency and secretory component deficiency may be contributing factors in the development of diarrhea in Waldenstrom's macroglobulinemia.