Adrenal Cushing's syndrome due to bilateral macronodular adrenal hyperplasia: Prediction of the efficacy of β-blockade therapy and interest of unilateral adrenalectomy

Abstract

Bilateral adrenalectomy is the standard treatment for Cushing's syndrome (CS) related to ACTH-independent bilateral macronodular hyperplasia (AIMAH), although it imposes life-long adrenal insufficiency. This study reports a clinical case in order to discuss the clinical interest of pharmacological β-blockade of illegitimate membrane receptors and unilateral adrenalectomy as alternatives to bilateral adrenalectomy for treatment of CS due to AIMAH. Evidence for cortisol stimulation by upright posture and insulin-induced hypoglycemia in a patient with CS related to AIMAH led us to try β-blockers as a therapeutic test and then as a first line treatment. Thus, a 3-day β-blocker test (320mg/d propranolol) induced normalization of cortisol secretion, with return of hypercortisolism at the end of the test. A long term treatment with 320mg/d propranolol allowed sustained normalization of cortisol secretion and progressive disappearance of Cushingoid features but after 8 months the patient complained of Raynaud's syndrome and fatigue. Lowering propranolol dosage or switching to atenolol was less efficient to reduce cortisol levels. Unilateral adrenalectomy was then performed as a second line treatment, leading to normalisation of the 24h urinary cortisol without adrenal insufficiency. Long term control of blood pressure and glycemia were observed during a 7-year follow-up without β-blocker. In conclusion, a 3-day propranolol test may identify patients with AIMAH who can benefit from a long term β-blocker treatment. In case of intolerance to β-blocking agents, unilateral adrenalectomy may allow for long term control of Cushing's syndrome related to AIMAH without adrenal insufficiency.