During pregnancy, there is no established treatment for idiopathic hyperaldosteronism (IHA), the most common form of primary aldosteronism due to bilateral adrenal hyperplasia. Here, we report the case of a pregnant patient with IHA who was successfully treated with esaxerenone, a nonsteroidal mineralocorticoid receptor (MR) antagonist. A 39-year-old woman was diagnosed with IHA and commenced on nifedipine 20 mg daily because she desired to be pregnant. After 1 year, she became pregnant. Her blood pressure was well controlled until 34 weeks of gestation when her home blood pressure became elevated up to 140/90 mmHg. Although the dose of nifedipine was increased to 80 mg daily, her blood pressure increased to 151/97 mmHg, and urinary test showed proteinuria of 2+ in 35 weeks of gestation. She was diagnosed with superimposed preeclampsia (SPE) and additionally treated with esaxerenone. Her blood pressure decreased to 120-140/98-100 mmHg and the proteinuria improved to ±. A successful cesarean section at 37 weeks resulted in the delivery of a healthy baby boy. Her blood pressure was well controlled although esaxerenone was discontinued 2 weeks after the delivery. This is the first case of a pregnant woman who was safely treated with esaxerenone despite being a female at advanced maternal age who had been diagnosed with IHA and developed SPE. Further studies are needed to investigate the efficacy and safety of nonsteroidal selective MR antagonist in similar pregnant patients with IHA to establish better treatment strategy for these patients.
