Newer parameters of the octreotide test in patients with acromegaly.

Purpose: Predicting the therapeutic effects of first-generation somatostatin receptor ligands (fg-SRLs) is important when assessing or planning effective treatment strategies in patients with acromegaly. The oft-used maximum growth hormone (GH) suppression rate parameter of the octreotide test has a suboptimal predictive value. Therefore, this study explored newer parameters of the octreotide test for predicting the therapeutic effect of long-acting fg-SRLs.

Methods: In this single-center retrospective study, the octreotide test parameters and the therapeutic effects of fg-SRL at 3 months were investigated in 45 consecutive treatment-naïve patients with acromegaly between April 2008 and March 2023. Additionally, the relationship between the octreotide test parameters and the therapeutic effects of fg-SRLs was investigated. Tumor shrinkage was evaluated based on changes in the longitudinal diameter of the macroadenomas. The area GH suppression rate-time under the curve (AUC) and the time to nadir GH level were calculated and compared with the maximum GH suppression rate.

Results: The AUC estimated reductions in serum insulin-like growth factor I, and tumor shrinkage. The time to nadir GH level predicted tumor shrinkage more robustly than the maximum GH suppression rate in patients with macroadenoma.

Conclusion: The AUC and time to nadir GH level may potentially be newer parameters of the octreotide test for estimating the therapeutic effect of fg-SRLs.