Introduction Posaconazole is an azole used in treatment and prophylaxis of a broad spectrum of fungal infections. Antifungals such as ketoconazole have been shown to cause primary adrenal insufficiency (AI) as a result of direct inhibition on the steroidogenesis pathway. There is only one reported case of primary AI induced by posaconazole in a patient with mucormycosis. We report a case of posaconazole-related primary AI. Case A 63-year-old man with chronic myelomonocytic leukemia was admitted for fatigue and intermittent nausea and vomiting. He had recently discontinued prophylactic posaconazole 300 mg daily. He was assessed for AI with a morning cortisol of 1.9 mcg/dL followed by a failed cosyntropin stimulation (CS) test. Adrenocorticotropic hormone (ACTH) level was 154.6 pg/mL with negative 21-hydroxylase antibodies. The patient's symptoms improved with initiation of hydrocortisone and fludrocortisone. One year after discontinuation of posaconazole, he underwent a repeat CS test which showed normal adrenal function with normal ACTH at 34.1 pg/mL. Conclusion In this case, we demonstrate that prolonged use of posaconazole is associated with primary AI. As use of posaconazole increases, knowledge of the potential risk of AI is important and must be included in the differential diagnosis when these patients present with hypotension, hypoglycemia, and failure to thrive.

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