Giardiasis as a cause of hypokalemic myopathy in congenital immunodeficiency.

Hypokalemic myopathy may occur in several infections. We report a case of severe and transient myopathy secondary to hypokalemia induced by chronic intestinal infection with Giardia lamblia in a patient with common variable hypogammaglobulinemia. Hypokalemic myopathy is documented by serum enzymes, electromyography (reduction in the number of voluntarily activated motor unit action potentials and an increase in polyphasic motor unit action potentials, and pathological changes (hematoxylin-eosin, ATPase staining). The case reported involves hypokalemic myopathy induced by giardiasis in a patient with primary immunodeficiency; the histopathological changes observed in a skin/muscle biopsy from this patient are described for the first time.