Immediate postoperative growth hormone level and early postoperative oral glucose tolerance test as predictive tools for the long-term surgical remission in acromegaly

Abstract

[한글]

[영문]OBJECTIVE: The suppression of growth hormone (GH) in an oral glucose tolerance test (OGTT) has been accepted as the most reliable parameter for the determination of remission in acromegaly. In this study, we analyzed the immediate postoperative GH level and 1 week postoperative OGTT as the early predictive tools of long-term surgical remission.METHODS: Three hundred thirty-eight patients with acromegaly underwent transsphenoidal adenomectomy between Jan 1992 and Dec 2008 by a single neurosurgeon (S.H. Kim). In these patients, GH was measured 2, 6, 12, 18, 24, 48, 72 hours postoperatively, and OGTT was performed 1 week after operation, in every 6 months for the first 3 years, and annually thereafter. In this study, 194 patients who had been followed up longer than 1.5 years with at least three times of OGTT were evaluated. These included 153 patients with surgical remission and 41 patients with non-remission, and their outcomes in each group were evaluated and compared.RESULTS: Patients were followed up for 1.5?12.4 years (mean duration, 3.80±0.17 years) after operation with 3-15 times (mean, 5.0±0.14) of postoperative OGTT. One hundred seventy-seven patients underwent gross total resection and remission was achieved in 153 patients. These included 10 patients with invasion of cavernous sinus. In 41 patients with non-remission, 17 patients underwent incomplete resection which included patients with cavernous sinus invasion. All immediate postoperative 2, 6, 12, 18, 24, 48, 72-hour GH levels showed good predictability for long-term surgical remission (P<0.05), especially, 24-hour postoperative GH level had the highest predictability (0.67±0.06 ng/mL in a remission group vs 7.12±2.06 ng/mL in a non-remission group, P<0.05). The nadir GH level in 1 week postoperative OGTT was 0.55±0.05 ng/mL in a remission group and 8.53±2.35 ng/mL in a non-remission group. One week postoperative OGTT had 81.7% of sensitivity and 95.1% of specificity for the remission when 1 ng/mL was chosen as a cut-off value for the determination of remissionCONCLUSION: Immediate postoperative GH levels and OGTT are reliable values that predict long-term surgical remission in acromegaly. These results suggest that we might consider early re-operation when immediate postoperative GH levels or 1 week postoperative OGTT indicate low probability of long-term remission and postoperative magnetic resonance imaging shows a suspicious remnant tumor.