PurposeTo evaluate the efficacy of a novel recombinant human thyroid-stimulating hormone (ZGrhTSH) as an alternative to thyroid hormone withdrawal (THW) in dynamic assessment of DTC patients.MethodsThis phase 3, open-label, multicenter trial, conducted across 27 sites in China, employed a self-controlled design to enroll patients. Eligible patients had previously undergone total or near-total thyroidectomy, with or without RAI therapy. During both the ZGrhTSH-stimulated phase and the THW phase, Dx-WBS and serum Tg measurements were performed on all participants. The study focused on the concordance of Dx-WBS results, stimulated Tg levels, and their combination in patients across the two phases. Additionally, the safety and immunogenicity profiles of ZGrhTSH were assessed as well.ResultsIn the assessment of radioiodine uptake and stimulated Tg levels, ZGrhTSH demonstrated efficacy comparable to that of THW. The concordance rate for scans between the two phases was 88.2% (95% CI: 83.7-92.7%). When setting stimulated Tg levels with a cutoff of 1 ng/mL, the concordance rate was 90.4% (95% CI: 86.1-94.6%), and the concordance of scans combined with stimulated Tg was 93.6% (95% CI: 90.1-97.1%). Adverse events associated with ZGrhTSH were reported in 22 patients (10.9%), all of which were mild and transient, graded as 1 or 2.ConclusionZGrhTSH showed non-inferior performance in detecting radioiodine uptake and serum Tg, and could be an effective and safe alternative for the dynamic evaluation of DTC patients.Trial registrationClinicalTrials.gov, NCT04971473. Registered July 7, 2021.