LAUSR

CONTEXT Somatostatin analogs are recommended for preoperative therapy in Thyrotropin secreting pituitary adenomas (TSHomas). Octreotide suppression test (OST) was designed to differentiate TSHomas with Resistance to Thyroid Hormones, while its ability to test sensitivity of SSA has not be fully studied. OBJECTIVE To test the sensitivity of SSA in TSHomas with OST. PATIENTS We collected 48 pathologically confirmed TSHoma patients with complete 72 hours' data of OST into analysis. INTERVENTION Octreotide suppression test MAIN OUTCOME: Sensitivity timepoint and cutoff of OST RESULTS: During the entire OST, the TSH descended maximally 89.07% (73.85%,96.77%), while the FT3 and FT4 declined slowly [43.40% (37.80%,54.44%) and 26.59% (19.01%,33.13%), respectively]. The 24th hour was the timepoint wherein the stability occurs for TSH and the 48th hour for FT3 and FT4 during OST. In the patients who received both short- and long-acting Somatostatin analogs (SSA), the 24-hour timepoint was the most predictive timepoint for the percentage of TSH decline (Spearman's rank correlation analysis, r=0.571, p<0.001), while the 72-hour timepoint was optimal for predicting the magnitude of TSH decline (Spearman's rank correlation analysis, r=0.438, p=0.005). In the 24th timepoint, a positive correlation was also observed between TSH suppression rate and the percentage decrease and absolute value decrease of FT3 and FT4. Furthermore, in patients treated with long-acting SSA, the 72-hour timepoint was optimal for predicting both the percentage (Spearman's rank correlation analysis, r=0.587, p=0.01) and magnitude (Spearman's rank correlation analysis, r=0.474, p=0.047) of TSH decline. The 24th hour was the optimal timepoint with 44.54% (50% of median value of TSH in 72hOST) decrease of TSH being the observing cutoff. The adverse effect of OST was predominantly occurred in gastrointestinal system and no severe event occurred during OST. Paradoxical response could occur in OST and it did not influence the effect of SSA as long as sensitivity was confirmed. High level of hormonal control was achieved in the SSA-sensitive patients. CONCLUSION OST can be used as efficient tool to guide the adequate use of SSA. This article is protected by copyright. All rights reserved.