Malabsorption Due to Chronic Giardiasis as a Presenting Symptom of Common Variable Immunodeficiency.

Common variable immunodeficiency (CVID) is a primary immunodeficiency that presents with a broad spectrum of clinical manifestations. We report the case of a 33-year-old man, initially referred to the outpatient internal medicine clinic for anemia. At the evaluation, the patient complained of diarrhea and unintentional weight loss for the last six months. He had no known medical conditions, but his previous medical history highlighted recurrent respiratory infections since childhood and also oral ulcers. The investigation identified iron-deficiency anemia caused by a malabsorption syndrome due to chronic giardiasis (Giardia lamblia cysts identified in fecal culture and Giardia lamblia trophozoites identified in the villi epithelium). Further investigation revealed bilateral bronchiectasis and splenomegaly. Suspecting CVID, a serum protein electrophoresis was performed, which showed a flattening of the gamma region, corresponding to a severe deficit of immunoglobulin (Ig) G, IgA, and IgM. A deficiency in the production of IgG in response to immunizations was confirmed, and the other causes of hypogammaglobulinemia were excluded. Therefore, a diagnosis of CVID was established. Malabsorption due to chronic giardiasis is a rare cause of iron deficiency anemia and an unusual presentation of CVID.