A Case of Pseudohyperaldosteronism Induced by Yokukansan and Shakuyakukanzoto That Resulted in Severe Hypokalemia

Pseudohyperaldosteronism can be induced by the excessive use of Chinese herbal medicines (Kampo medicines), resulting in serious disorders. We report a case of pseudohyperaldosteronism induced by two Kampo medicines which resulted in severe hypokalemia. A 70-year-old woman was hospitalized for a left calcaneal fracture. She had no subjective symptoms other than trauma. On her admission, blood test results revealed a low serum potassium level of 2.4 mmol/L by chance, as well as low levels of both renin and aldosterone. The patient had been taking 5 g of Yokukansan per day for the past three months. In addition, she was on 5 g Shakuyakukanzoto per day for three months until a month prior to hospitalization. The daily licorice content from the aforementioned herbs was 1.0 g and 4.0 g, respectively. After hospitalization, the administration of the Kampo medicines was discontinued, and 610 mmol of potassium was administered over a period of 13 days, which resulted in the normalization of serum potassium levels. Pre-existing hypertension slowly improved as well. Patients consuming licorice at doses of 2.5 g per day or more, as in our case, are at a high risk of developing pseudohyperaldosteronism. Furthermore, the risk is particularly high with long-term licorice consumption as well as for women and elderly patients. To this end, high-dose potassium supplementation may be necessary for normalizing serum potassium levels. Therefore, awareness regarding the adverse effects of licorice is crucial, even in cases of low dosages of licorice.