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

Purpose: Acromegaly patients occasionally achieve either of the remission criterion of IGF-1 or GH level postoperatively; however, treatment for patients with discordant IGF-1 and GH levels 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: Overall, 110 acromegaly patients underwent initial surgery and a 75-g oral glucose tolerance test (OGTT) 3 months postoperatively. Of the 110, 23 patients with normal IGF-1 and nadir GH levels of ≥ 0.4 µg/L on OGTT (high-GH group) were categorized into three subtypes based on their repeated examinations 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: 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 women (P = 0.0178) than men 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 that 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 considering the possibility of recurrence in the future.