Background: In some patients with adrenal tumors cortisol regulation may be under the control of abnormal or ectopic hormone receptors. The objective of this study is investigate the presence of these aberrant receptors in subjects with adrenal incidentaloma and biochemical criteria of subclinical hypercortisolism.
Patients and methods: We studied seventeen patients with adrenal incidentalomas, ten patients with a unilateral tumor (age 4870, M/F: 4/6) and seven patients with bilateral tumors (age 5368, M/F: 5/2), and biochemical features of subclinical cortisol hypersecretion. They were studied for plasma cortisol responses to various stimuli: upright posture, meal, terlipressin, cinitapride, combined hypothalamic-hormones (TRH and LHRH) and ACTH. Six normal controls were similarly studied. All subjects were given dexamethasone orally in order to avoid any ACTH-dependent variation of plasma cortisol. Responses to stimulation were classified as negative (increase of cortisol <25%), partial (2549%) and positive (≥50%).
Results: Fourteen out of seventeen patients responded to at least one stimulus other than ACTH. The most frequent cortisol response was obtained after terlipressin administration. A positive response to terlipressin was seen in 3/4 patients with bilateral tumors and in all of the patients (5/5) with unilateral incidentaloma. A partial to positive response was seen after the administration the others stimulus except to cinitapride. No response was observed in control subjects. Plasma ACTH remained supressed in all subjects throughout the study.
Conclusions: Aberrant membrane receptors detected by stimulation tests appear to be common in unilateral and bilateral incidentalomas with subclinical autonomous cortisol hypersecretion. The identification of these receptors could provide the novel opportunity to treat some of these patients with pharmacological agents.