Incidental findings of adrenal tumours,"incidentalomas", occur in 1-5 % in the general population and 10-25 % of these patients will exhibit biochemical mild hypercortisolism. Although the patients do not have clinical signs of classical Cushing's syndrome, they have an increased risk for hypertension, dyslipidemia, diabetes mellitus, osteoporosis and obesity. The hypothesis of the study is, that surgery of the adrenal adenoma responsible for the increased secretion of cortisol, will in part cure or ameliorate the metabolic syndrome.
Inclusion Criteria: * Adrenal tumour with biochemical mild hypercortisolism defined as pathological dexamethasone suppression test (cortisol \> 50 nmol/L at 8.00 am after 1 mg dexamethasone at 10 pm, plus one of the following criteria * Low or suppressed adrenocorticotropic hormone (ACTH) * Low or suppressed dehydroepiandrosterone (DHEA) * No or pathological circadian rhythm of cortisol Exclusion Criteria: * Increased levels of 24 hours urinary excretion of cortisol * Pregnancy or lactation * Inability to understand information or to comply with scheduled follow-up * Mild hypercortisolism with bilateral adrenal tumours, without a gradient (lateralization on venous sampling)