Correlation between Different Postoperative Serum Cortisol Cut-off Values Measured in Different Periods and Long-term Outcomes in Patients with Cushing's Disease

Objective To investigate the correlation between different postoperative serum cortisol cut-off values measured in different periods and the long-term outcomes in patients with Cushing's disease (CD). Methods The clinical data of 102 CD patients undergoing transsphenoidal surgery (TSS) in Peking Union Medical College Hospital from May 1985 to July 2008 were analyzed retrospectively. The differences of long-term outcomes were compared between patients with cortisol levels below 2 μg/dl (2 μg/dl group) and levels between 2 and 5 μg/dl (5 μg/dl group) in the 1^st postoperative day and 3 and 6 months after surgery. Results The mean follow-up duration was (10.7±1.7) years (range:5-29.1 years). Among these 102 patients,the disease was cured in 74 patients (72.5%) and recurred in 28 patients (27.5%). On the 1^st postoperative day,there were 63 patients in the 2 μg/dl group,in which 48 patients (76.2%) achieved long-term cure;there were 39 patients in the 5 μg/dl group,in which 26 (66.7%) achieved long-term cure. The difference was not statistically significant (χ²=1.097,P=0.295). Three months after TSS,the long-term cure rate was 84.2% (48/57) in the 2 μg/dl group,which was significantly higher than that (65.0%,26/40) in the 5 μg/dl group (χ²=4.795,P=0.029). Six months after TSS,the long-term cure rate was 88.7% (47/53) in the 2 μg/dl group,which was significantly higher than that(69.2%,27/39) in the 5 μg/dl group(χ²=5.400,P=0.020). Conclusion The serum cortisol level of below 2 μg/dl is more useful than 2-5 μg/dl 3 months and 6 months after surgery in predicting the prognosis of CD patients.