Food-dependent Cushing's syndrome: from molecular characterization to therapeutical results

Abstract

Cortisol secretion in ACTH-independent macronodular adrenal hyperplasia (AIMAH) may be regulated by the aberrant expression of several G-protein-coupled receptors. Bilateral adrenalectomy is the treatment of choice in most cases. We searched for aberrant receptor expression in a patient with AIMAH and evaluated the response to medical and surgical treatment. A 35-year-old woman with amenorrhea, hirsutism, and hypertension presented ACTH-independent cortisol secretion with high androgen levels. Abdominal computed tomography showed bilateral adrenal macronodules (4.5 cm right and 1.0 cm left). Scintigraphy with I(131)-norcholesterol showed bilateral uptake, prevalent on the right side. Several in vivo stimulation tests were assessed before and after treatment and in vitro studies were performed after unilateral adrenalectomy. Plasma cortisol increased after a standard meal test (60%) and oral glucose loading (147%), and the response was blunted by pretreatment with 100 microg s.c. octreotide. The therapy with long-acting release octreotide (octreotide-LAR) showed an improvement in urinary free cortisol (UFC) levels. Unilateral adrenalectomy was performed and histopathology revealed macronodular AIMAH. Cortisol and androgens increased after perifusion of tumoral tissue with glucose-dependent insulinotropic polypeptide (GIP), and GIP and LH-receptor overexpression was found in both the adrenal nodules and the adjacent cortex. After surgery, UFC and androgen levels normalized followed by clinical improvement. GIP and LH-receptor expression may coexist in AIMAH, influencing the functional and morphological phenotype. Aberrant hormone receptor expression enables specific pharmacological treatment, but long-term studies are needed to evaluate its real efficacy. Unilateral adrenalectomy may be a safe initial option, particularly for asymmetric bilateral adrenal enlargements.