Sir,

I read with interest the article by Harsum et al.1 The authors state that the diagnosis of common variable immunodeficiency (CVID) is made on the clinical history of recurrent infection, usually of the respiratory tract, in the context of reduced total IgG. However, Some points need to be clarified. Other causes of hypogammaglobulinaemia, for example, nephrotic syndrome and haematological malignancies, must be ruled out before the diagnosis of CVID has been made. So complete blood count with differential, urine protein analysis must be performed.2 History of medications is also crucial. Corticosteroids, gold salts, penicillamine, antimalarial drugs, sulphasalazine, fenclofenac, phenytoin, and carbamazepine can contribute to hypogammaglobulinaemia.2