Endocrine Abstracts

Background: First-line therapy of ACTH-independent Cushing’s Syndrome (CS) is the resection of the underlying tumor in all cases. After surgical cure of CS, most patients develop transient secondary adrenal insufficiency with a variable time of recovery. Adrenal function testing can identify patients who may require glucocorticoid replacement.

Methods: We reviewed 61 patients diagnosed with ACTH-independent CS excluding 6 with adrenocortical carcinoma; 40 underwent unilateral adrenalectomy for adrenocortical adenoma or bilateral macronodular hyperplasia. Postoperatively, blood was sampled for plasma cortisol levels at 08:00AM; 4 hours and 24 hours after administration of 1 mg Synacthen depot im. Glucocorticoid replacement was started if basal plasma cortisol<5 μg/dl, or a stimulated plasma cortisol<20 μg/dl. Follow up was performed at 3, 6, 9 months and 1 year or more in selected cases, in order to see the duration of glucocorticoid replacement, morphological aspect of the contralateral adrenal and complications remission.

Results: Between 2005–2015, 55 patients were diagnosed with benign ACTH-independent CS in our clinical department, 7 men and 48 women, aged 52±11.68 (range 26–76): 43 adenomas and 12 bilateral macronodular hyperplasia. Tumor size ranged from 16 to 140 mm (39±20.2 mm). Subclinical Cushing (pathological dexamethasone test only) was diagnosed in 29 cases and overt Cushing in 26 cases. Mixed glucocorticoid and androgen secretion was found in four cases. From all cases, forty underwent unilateral adrenalectomy; six patients were excluded because of missing data. From the remaining 34 patients, 18 were with secondary adrenal insufficiency (15 with overt CS and 3 with subclinical CS), receiving replacement therapy 3–18 months after surgery. The decision of ceasing therapy was based on a stimulated cortisol ≥20 μg/dl. A longer period of substitution was required for those patients with atrophic contralateral adrenal at initial morphological evaluation.

Conclusion: Only about a half of the patients with CS develop postoperatively secondary adrenal insufficiency. The synacthen depot test is useful for the decision of starting or ceasing the replacement therapy.