Endocrine Abstracts

Background: The treatment of choice in patients with Cushing Disease (CD) is pituitary surgery (PS). A successful PS is generally followed by adrenal insufficiency (AI). Although the remission rate after PS may reach 96.6% of cases, approximately 1/3 of cured patients experience the recurrence of the disease during lifetime. The aim of this study was to analyze the duration of AI in relation with the recurrence of CD.

Materials and methods: We performed a retrospective analysis on patients with CD followed at our center between 1995 and 2017 and who met the following inclusion criteria: age above 18 years, presence of adrenal insufficiency 2–3 months after PS and a minimum follow-up of 3 years. Adrenal insufficiency was confirmed on either basal cortisol <3 μg/dl or a cortisol peak <18 μg/dl during consynthropin test (1 mcg or 250 μg). Recurrence was defined by high urinary free cortisol (UFC) levels and a positive dexamethasone suppression test (1 mg overnight or 2×2 mg: cortisol >1.8 mg/dl).

Results: According to the inclusion criteria we selected 54 patients. The mean follow-up was 6.6 years (median: 5 years, interquartile range (IQR): 4–9.25 years). The recurrence rate at 3 years was 11.1% (6/54) while the cumulative rate was 14.8% (8/54). Six out of eight patients experienced the recurrence in the first 3 years after PS, one patient at 4 years and one after 15 years. AI recovery rate without disease recurrence was 35.3% at 3 years with a cumulative rate of 48.8%. Comparison between the two groups (remission/recurrence) showed a similar gender ratio (F:M=8:1), BMI (25.4±4.1 vs.27.7±6.6, P=0.4), age at PS (43.5±16.1 vs 41.5±14.3 years, P=0.7). Also hormonal characteristics and radiologic features did not show any significant difference between the two groups. The duration of AI was the only parameter significantly different (median 24.3, IQR: 11.9–40 vs 10.7, IQR: 8.1–17.2). In particular, the recovery time of adrenal function represented a significant predictor for persistent remission (OR: 1.14, CI: 1.003–1.313, P=0.046). Using the duration of AI as diagnostic test for persistent remission we observed a good accuracy (AUC 0.91, P<0.001). The persistence of AI after 22 months had a PPV of 100% and NPV of 47% for persistent remission.

Conclusion: Our study show that the duration of adrenal insufficiency after PS in patients with CD may be a useful predictor for persistent disease remission.