Posaconazole-induced hypertension and hypokalemia due to inhibition of the 11b-hydroxylase enzyme

Posaconazole is an antifungal therapy reported to cause incident hypertension. Hypokalemia is also a known side effect. The combination of hypertension and hypokalemia suggests mineralocorticoid excess. We present the case of a 15-year-old adolescent male with hypertensive urgency while on prophylactic posaconazole therapy for a combined immunodeficiency. We identify the mechanism of posaconazole-induced hypertension to be inhibition of the 11b-hydroxylase enzyme, resulting in elevated levels of the mineralocorticoid receptor activator deoxycorticosterone. Loss of function of the 11b-hydroxylase enzyme is responsible for a rare form of congenital adrenal hyperplasia and can be associated with life-threatening adrenal crisis.