MON-148 Weight Gain in Patients with Acromegaly after Pituitary Surgery: Predictive Factors and Insights - A Large Single Center Experience

Abstract M. Stack: None. E.V. Varlamov: Grant Recipient; Self; Pfizer, Inc., Lumiio, Recordati. D.S. Lim: None. F. Langlois: Consulting Fee; Self; Recordati, Ipsen. M. Fleseriu: Consulting Fee; Self; Amryt, Camurus, Crinetics, Ipsen, Recordati. Grant Recipient; Self; Amryt, Crinetics, Ionis Pharmaceuticals Inc., Recordati. Background: Excessive growth hormone (GH) and insulin-like growth factor 1 (IGF-1) in patients (pts) with acromegaly (acro) leads to skeletal overgrowth and metabolic changes. GH lipolytic effect ↑ lean body mass, ↓ fat mass, and ↑ insulin resistance. Partial reversal of such changes can occur after GH adenoma surgery. At follow-up (f/u), weight outcomes postoperatively (postop) vary in studies from no change to significant weight gain. Objective: Enhance understanding and identify predictors of postop weight changes in pts with acro. Design & Method: IRB approved retrospective review of pts with acro who underwent pituitary surgery at OHSU (2006-2022) with >12 months (mo) f/u. Excluded: pts who started/stopped weight- altering drugs or were in a weight loss program (3 mo pre- to 12 mo postop), pregnancy, and uncontrolled hyper/hypothyroidism. Age, sex, weight, BMI, IGF-1, GH, pituitary function status, HbA1C, comorbidities, and medications were recorded. Data analysis: SPSS29, Excel. Results: 15 pts were excluded, for a final cohort of 93 pts (53 females), age 45.4 ± 17.1 years, BMI 29.5 ± 6.5 kg/m2, mean f/u 44.4 ± 23.5 mo. 53 pts were in remission at 12 mo. 65% gained weight at 12 mo postop; 43% > 3% and 32% > 5%. Mean weight gain was 2.6 ± 7.2 kg (2.7%) from baseline to 12 mo postop (89.9 ± 23.9 vs 92.5 ± 26.4 kg, p < 0.001), with no significant sex-based differences at 3, 6, and 12 mo f/u. Age, preop BMI, preop GH, preop IGF-1xULN, % ↓ in IGF-1, acro remission status, pituitary deficiencies, DM2, hyperlipidemia, hypertension and obstructive sleep apnea were not significantly associated with weight gain at 6 and 12 mo. Females with > 3% weight gain had higher preop IGF-1xULN vs those with < 3% weight gain at both 6 (p = 0.036) and 12 mo (p = 0.01). No difference in weight gain at 12 mo was observed in treatment-naïve vs previously treated pts. Postop medications for acro were not associated with weight change at 6 and 12 mo. Weight gain tended to be higher in pts with pituitary surgery pre-2016 (3.8% vs 1.3%, p = 0.057).Discussion: This large single center study highlights that 65% pts with acro gained weight at 12 mo postop, with a noteworthy proportion gaining > 3% and 5%. Weight gain is relatively similar with previous reports: 1-3 kg in pts with surgical/medical remission. Among multiple factors examined, higher preop IGF-1 was associated with weight gain in females only. The mechanism of observed sex difference needs further study. Pts with surgery since 2016 tended to gain less weight, possibly due to proactive discussion with pts of weight gain risk at our Center. Conclusion: Our findings emphasize a risk of significant postop weight gain in pts with acro; in females, weight gain of > 3 % was associated with preop IGF-1 levels. Given that obesity increases cardiovascular risk, lifestyle or pharmacological methods to prevent weight gain after pituitary surgery should be actively considered. Monday, June 3, 2024