Fluconazole and acetazolamide in the treatment of ectopic Cushing's syndrome with severe metabolic alkalosis

Cushing's syndrome (CS) due to ectopic ACTH production accounts for about 10% of all types of CS and is frequently associated with metabolic alkalosis. Treatment of CS involves surgical resection and/or medical therapy to control hypercortisolism. We present the case of an 80-year-old woman affected by CS due to an unknown cause. The patient had severe metabolic alkalosis with refractory hypokalemia. To treat the underlying CS, fluconazole was initiated due to unavailability of ketoconazole. In spite of markedly decreasing cortisol levels, metabolic alkalosis persisted. Treatment of metabolic alkalosis with acetazolamide was thus initiated and pH levels successfully lowered. This case report shows that hypercortisolism can be effectively treated with fluconazole in cases where ketoconazole is unavailable or not tolerated and that persistent severe metabolic alkalosis caused by glucocorticoid excess can be safely and successfully treated with acetazolamide. LEARNING POINTS: Hypercortisolism can be effectively treated with fluconazole where ketoconazole is unavailable or not tolerated. Glucocorticoid excess can cause severe metabolic alkalosis. Persistent severe metabolic alkalosis can be safely and successfully treated with acetazolamide.