Endocrine Abstracts

Background: Pituitary surgery is the primary therapy for Cushing’s disease (CD). Basal cortisol level (BCL) is measured postoperatively to evaluate the immediate efficacy of surgical treatment, but no definitive cut-off value has yet been determined as reliable. Our pituitary-dedicated centre uses an arbitrary BCL less than 50 nmol/l as expected early remission marker, identifying all patients with higher BCL as a risk group for early surgical failure.

Objectives: (i) To assess whether BCL is indicative of immediate outcome of pituitary surgery as first-line CD treatment (ii) If (i) is affirmative, to ascertain the optimal BCL cut-off value based on our centre data

Methods: This single centre retrospective study reviewed 42 consecutive patients who underwent pituitary surgery as initial therapy for CD. BCL was measured during the first postoperative week. Surgical success was defined as biochemical remission at 3-month follow-up, whereas surgical failure was defined as persistent CD at 3-month follow-up. ROC curve was used for statistical analysis.

Results: Out of 42 patients, 36 were in remission and 6 had persistent CD at 3-month follow-up. Postoperative BCL ranged 11-2326 nmol/l. According to ROC curve (AUROC:0.926; 95%CI:0.843,1.0;P = 0.001), BCL was an excellent indicator of early surgical outcome. A cut-off value of 50 nmol/l we ordinarily used was 100% sensitive and 58.3% specific for determining surgical success, meaning 41.7% of patients perceived as potential immediate surgical failure actually achieved remission. A more appropriate cut-off value of 317 nmol/l (sensitivity 100%, specificity 80.6%) still detected all surgical failures with only 19.4% of successful outcomes having higher BCL.

Conclusions: (i) Postoperative BCL indicates early outcome in pituitary surgery as initial treatment for CD. (ii) Postoperative BCL higher than we previously thought can be found in successful early outcomes, justifying the wait-and-see approach. Further studies on larger samples are required to determine the optimal cut-off value.