Abnormal Dexamethasone Suppression Tests in a Rifapentine-Treated Patient With Primary Aldosteronism

Aldosterone-producing adenoma (APA) is a main cause of primary aldosteronism (PA). Given that a large benign-appearing unilateral masse (>1 cm in diameter) may represent an aldosterone and cortisol-co-secreting adenoma, dexamethasone suppression testing is required in such patients to exclude or confirm the diagnosis of hypercortisolism. Tuberculosis is highly prevalent in China, and rifamycins are often used in these patients. Rifapentine belongs to the rifamycin family, and we herein for the first time report a case of misdiagnosis of hypercortisolism due to rifapentine use in a patient with APA. Thus, in patients treated with rifapentine, diagnosis of hypercortisolism based on dexamethasone suppression tests can be very misleading.