SAT-079 Early Biochemical Predictors of Surgical Remission in Patients with Acromegaly

Abstract Disclosure: D.H. Chen: None. B.L. Chang: None. A.N. Mamelak: None. V. Bonert: None. J.D. Carmichael: None. O. Cooper: None. Background: There is no consensus on criteria for early biochemical testing after acromegaly surgery to predict sustained biochemical remission. Our aim was to assess optimal postoperative markers and timepoints for remission. Methods: The prospective study enrolled patients with acromegaly from 2006-2023. Insulin like growth factor (IGF-I), IGF1/upper limit normal (ULN) ratios, and timed growth hormone (GH) levels were collected on oral glucose tolerance test (OGTT) on postoperative day (POD) 1 and weeks 6, 12, and 52. Patients were divided into group 1 (OGTT nadir GH <1 μg/L, normal IGF-1), group 2 (nadir GH >1 μg/L, normal IGF-1), group 3 (nadir GH <1 μg/L, elevated IGF-1), and group 4 (nadir GH >1 μg/L, elevated IGF-1). Primary endpoint was normal IGF-1 at weeks 12 and 52. Nominal variables were compared with Fisher’s exact test, continuous variables compared with Wilcoxon rank-sum test, and relative risks (RR) calculated. Results: 41 patients were enrolled, and 20 analyzable for all timepoints. Median age was 46 years (IQR 41.5-56.5), median tumor size 12 mm (IQR 10-23), and 8 were female. Overall remission at 12 and 52 weeks was 70% and 80%, respectively. At week 6, 13 were in group 1, 1 in group 2, 3 in group 3, 2 in group 4. By week 52, 2 patients moved from groups 3 and 4 to group 1 while those in group 1 at week 6 remained in group 1. Compared to those with persistent disease, week 12 remission was associated with less optic chiasm compression (33% vs. 67%, p=0.04), lower median Ki-67 (0.015 [IQR 0.005-0.020] vs. 0.030 [IQR 0.018-0.043], p=0.03), lower median POD1 GH (0.75 [IQR 0.28-1.20] vs. 1.90 [1.53-9.43] μg/L, p=0.002), POD1 GH <1 μg/L (100% vs. 0%, p=0.01), GH nadir <1 μg/L (92% vs. 8%, p=0.02), and lower median POD1 IGF-I/ULN (1.39 [IQR 0.99-1.62] vs. 2.04 [IQR 1.62-3.23], p=0.01). Predictors of remission included POD1 GH <1 μg/L (RR [95% confidence interval] = 2.20 [1.15-4.20]) and GH nadir <1 μg/L (RR = 2.44 [0.98-6.08]). At 1 year, compared to those with persistent disease, remission was associated with week 12 remission (100% vs. 0%, p=0.003), no optic chiasm compression (100% vs. 0%, p=0.003), lower median Ki-67 (0.015 [IQR 0.005-0.020] vs. 0.033 [IQR 0.023-0.046], p= 0.01), lower median POD1 GH (0.85 [IQR 0.38-1.20] vs. 2.55 [1.38-21.28] μg/L, p=0.01), GH nadir <1 μg/L (100% vs. 0%, p=0.01), and lower median POD1 IGF-I/ULN ratio (1.41 [IQR 1.02-1.65] vs. 2.46 [IQR 1.72-3.67], p=0.02). Predictors of remission included remission at week 12 (RR = 3.00 [0.97-9.30]) and GH nadir <1 μg/L (RR = 2.00 [1.00-4.00]). Discussion: POD1 GH <1 μg/L and OGTT nadir <1 μg/L but not IGF-1 levels were predictive of remission at week 12. At week 52, only nadir <1 μg/L was predictive of remission. Remission at week 12 was maintained at 1 year. Our study suggests that POD1 OGTT may be more predictive of biochemical remission at 1 year compared to POD1 GH and could be incorporated in early postoperative assessments. Presentation: Saturday, July 12, 2025