Glycyrrhizin (licorice)-induced hypokalemic myopathy. Report of 2 cases and review of the literature.

Fifty-nine cases of glycyrrhizin (licorice)-induced hypokalemic myopathy (GIHM), 2 females treated in our departments (85 and 73 years old) and 57 cases reported in the literature were studied, and conditions leading to the onset, factors, clinical manifestations, laboratory assessments, muscle biopsy findings, treatment and outcome were discussed. The 59 GIHM cases comprised 32 men, 25 women and 2 patients without record of sex; the average age was 55.2 years. In many cases, conditions leading to the onset of GIHM were habitual licorice ingestion, ingestion of antituberculosis agents containing licorice and long-term ingestion of licorice-containing agents for chronic gastritis, chronic hepatitis or chronic dermatitis. The combined use of hypotensive diuretic agents increased the risk of GIHM in an overwhelming number of cases. The main clinical symptom was flaccid quadriplegia in almost all cases, with muscle pain in 32.2% and peripheral dysesthesia in the extremities, manifested mainly by numbness (27.1%). Laboratory findings included a mean serum K+ value of 1.98 mEq/l (56 GIHM cases), a mean creatine kinase of 5,385.7 IU/l (n = 30), a mean blood aldosterone concentration of 2.92 ng/dl (n = 30; normal: 2.0-13.0 ng/dl) and a mean plasma renin activity of 0.17 ng/ml/h (n = 27; normal: 0.8-4.4 ng/ml/h). Muscle biopsy was performed in 17 of the 59 cases with resultant findings of myopathic changes consisting mainly of phagocytosis, necrotic fibers, vacuolar degeneration, together with sporadic neurogenic changes. Complete cure was attained in 57 of the 59 cases of GIHM by discontinued ingestion of glycyrrhizin (licorice) and potassium supplement.