Endocrine Abstracts

Purpose: Transsphenoidal endoscopic surgery (TSS) is the first-line treatment for Cushing’s disease (CD). However, persistence of hypercortisolism after TSS considered important problem. In this case search for CD remission predictors is actual.

Aim: To study the role of preoperative oral high-dose dexamethasone suppression test (HDDST) and pituitary magnetic resonance imaging (MRI) in the prognosis of CD remission after TSS.

Materials and methods: 101 patients (12 men, 89 women, mean age 41 years (15–72) with confirmed CD were included. HDDST and pituitary MRI were performed before the TSS in all cases. Invasive growth of adenoma was assessed by the Knosp classification. Postoperative examination was done one year after surgery. Remission criteria were: secondary adrenal insufficiency (the need for glucocorticoid replacement) or combination of normal midnight ACTH and serum cortisol levels, normal 24 hour urine free cortisol (UFC) excretion and serum cortisol suppression less than 50 nmol/l in 1-mg dexamethasone test. The optimal threshold value of serum cortisol suppression in the HDDST for prediction of CD remission after TSS was calculated by ROC-analysis.

Results: One year after surgery CD remission was confirmed in 63 patients, whereas in 38 patients hypercortisolism persisted. The optimal threshold value of serum cortisol suppression in the HDDST for prediction of CD remission after TSS was ≤74%. Test’s sensitivity and specificity were 86.8% and 84%, respectively. The probability of wrong prediction was 16% (P=0.0001). The results of TSS did not depend on the MRI adenoma size: remission of hypercortisolism was achieved in 64% of microadenomas and in 56% of macroadenomas. However in patients with non-invasive adenomas (Knosp 0–2) 47 of 50 patients with adenoma size ≥3 mm developed remission (94%), in 24 patients who had MRI-negative or <3 mm adenoma CD remission developed only in 11 cases (45.8%).

Conclusion: According to our data serum cortisol suppression more than 74% in preoperative HDDST may be used as a prognostic criterion for CD remission after TSS. The adenoma size may be used as a prognostic criterion in patients with non-invasive adenomas: the lesion size ≥3 mm is associated with high CD remission rate after TSS.