Acute myopathy associated with chronic licorice ingestion: reversible loss of myoadenylate deaminase activity.

A patient with acute rhabdomyolysis and absence of myoadenylate deaminase (MADA) associated with chronic licorice intoxication is presented. Clinical and laboratory examination of the patient and morphologic study over skeletal muscle were performed. The major effect of licorice intoxication is hypokalemia, which may explain most of the observed clinical symptoms and morphological changes. The absence of MADA may be a consequence of the direct toxic effect of licorice glycosides. To our knowledge, this is the first report in which a lack of MADA and chronic licorice intoxication has been shown to be associated with clinical, histochemical, biochemical, and morphological changes, which were completely reversed with potassium supplementation and licorice withdrawal.