The functional status of incidentally discovered bilateral adrenal lesions.

OBJECTIVE

To investigate autonomous cortisol and aldosterone secretion and insulin resistance (IR) indices, in patients with incidentally discovered bilateral adrenal lesions (BA).

PATIENTS

Thirty-six patients with BA, 113 patients with unilateral adrenal incidentalomas (UA) and 89 healthy subjects (C) with normal adrenal imaging.

MEASUREMENTS

All participants underwent adrenal imaging, baseline biochemical and hormonal measurements and the following investigations on consecutive days: (i) A 2-h oral glucose tolerance test (OGTT) (75 g) with glucose and insulin measurements every 30 min. (ii) An adrenocorticotrophin (ACTH) stimulation test with intravenous (i.v.) bolus administration of 250 μg of ACTH (1-24) and measurement of serum cortisol and aldosterone before and after 30 and 60 min. (iii) A low-dose dexamethasone suppression test (LDDST) (0·5 mg of dexamethasone every 6-h for 2 days) with cortisol measurement 6 h after the last dexamethasone dose and (iv) A NaCl (0·9%) postdexamethasone saline infusion test (PD-SIT) (2 l of NaCl 0·9% iv in 4 h) following the LDDST, with aldosterone measurement at the end of the test.

RESULTS

Cortisol and aldosterone cut-offs based on the mean + 2 SD values obtained from the C group following the LDDST and PD-SITs were calculated (34·11 nm and 74·83 pm, respectively). Based on the above cut-offs, autonomous cortisol and aldosterone secretion was found in 42·5 and 15·9% of patients with UA, and in 41·7 and 19·4% of patients with BA, respectively. In addition, 17·7% of patients with UA and 19·4% of patients with BA had concomitant autonomous cortisol and aldosterone secretion. Cortisol and aldosterone levels following the LDDST and PD-SIT were significantly higher in the BA compared to the UA group, respectively. Furthermore, patients with BA had more pronounced glucose levels and insulin resistance (IR) indices compared to patients with UA.

CONCLUSIONS

Patients with BA have more pronounced autonomous cortisol and aldosterone secretion and glucose metabolism alterations than patients with UA. Further studies are needed to evaluate the potential long-term consequences of these findings.