Reversible total IgA deficiency associated with phenytoin treatment

A 55-y-old male developed long-standing upper respiratory symptoms during phenytoin treatment of epileptic fits. Complete lack of serum IgA was noted repeatedly. Following replacement of phenytoin, normal IgA levels were found and a slow improvement in respiratory symptoms occurred. Immunoglobulin deficiency, in particular low levels of IgA, are not uncommon among phenytoin treated subjects. The occurrence of frequent respiratory infections in such patients justifies the investigation of immunoglobulin levels.