Management policy for postoperative acromegaly patients with normal IGF-1 and high GH levels on oral glucose tests

Abstract Purpose Acromegaly patients occasionally achieve either the remission criterion of IGF-1 or GH level postoperatively; however, whether additional treatment modalities should be administered in patients with unclear clinical courses remains unclear. This study aimed to clarify the clinical courses and features of postoperative patients with normal IGF-1 and high GH levels and support their management. Methods In total, 110 acromegaly patients underwent initial surgery and a 75-gram oral glucose tolerance test (OGTT) 3 months postoperatively. Patients with normal IGF-1 and high GH levels on OGTT (high-GH group) were categorized into three subtypes based on their clinical courses thereafter: late-remission type (nadir GH level on OGTT of < 0.4 µg/L later), recurrence type (elevated IGF-1 and GH levels later), and persistent type (normal IGF-1 levels and constantly high nadir GH levels on OGTTs). Results The proportion of patients in the high-GH group was 23.6%, and they were distributed as follows: late-remission type (n = 10), recurrence type (n = 5), and persistent type (n = 8). There were significantly more females (P = 0.0178) than males in the late-remission type, and patients in the persistent type had significantly larger tumors (P = 0.0110) and higher preoperative GH levels (P = 0.0018) than those who achieved complete remission 3 months postoperatively. Conclusion Careful monitoring without additional medications is recommended at first in acromegaly patients with normal IGF-1 and high GH levels because of the low recurrence rate, especially in female patients and patients with high preoperative GH levels.