Desiccated Thyroid Extract Combined With Levothyroxine for TSH Suppression Therapy in DTC

The global incidence of Differentiated Thyroid Cancer (DTC) is rising. While surgery followed by TSH suppression is the standard of care, achieving target TSH levels with levothyroxine (L-T4) monotherapy remains challenging, with only 25-70% of intermediate/high-risk patients attaining it within 6-8 months. This therapeutic dilemma stems from three key issues: impaired T4-to-T3 conversion due to DIO2 polymorphisms, the non-physiological hormone ratio of T4 monotherapy, and L-T4's narrow therapeutic window. This often results in an "under- versus over-suppression" paradox, increasing risks of recurrence, atrial fibrillation, and osteoporosis. Combining L-T4 with desiccated thyroid extract (DTE; T4:T3 ≈ 4:1) may overcome these limitations by bypassing DIO2 defects and providing a more physiological hormone profile, thereby potentially improving TSH control while mitigating side effects. Supported by the 2023 Chinese guidelines and our promising pilot data (82% cumulative target attainment at a median of 1.4 months), we propose a two-stage national study: a multicenter cohort study followed by a randomized trial, to generate high-level evidence for this combination therapy in high-risk DTC.

Sex

All

Minimum age

18 Years

Maximum age

70 Years

Inclusion Criteria:

* Stage 1 eligibility: (1) Age ≥ 18 years；(2) Histologically proven DTC after initial surgery (± ¹³¹I)；(3) ATA recurrence risk intermediate (low-intermediate or high-intermediate) or high；(4) On L-T4 monotherapy: TSH above target despite FT4 ≥ 90 % of normal upper limit；(5) Signed informed consent and agreement to follow-up. Stage 2 eligibility: (1) Age 18-70 years (inclusive)；(2) Histologically proven DTC undergoing first-time surgery；(3) ATA recurrence risk intermediate (low-intermediate or high-intermediate) or high；(4) Signed informed consent and agreement to post-operative follow-up.

Exclusion Criteria:

* (1) Non-DTC histology; (2) Hyperthyroidism, toxic adenoma, or toxic nodular goiter; (3) Malabsorptive GI disorders (e.g., H.-pylori gastritis, atrophic gastritis, celiac disease) or history of gastric bypass; (4) Hypersensitivity to levothyroxine or desiccated thyroid; (5) Angina, coronary artery disease, tachyarrhythmia, osteoporosis; (6) Concurrent malignancy; (7) Pregnant, lactating, or planning pregnancy within 12 months; (8) Severe COPD, hepatic or renal insufficiency, uncontrolled hypertension or diabetes, or any condition that could bias outcome assessment; (9) Chronic use of psychotropics, systemic glucocorticoids, amiodarone, chemotherapy, iron, thionamides, PPIs, or other drugs interfering with thyroid hormone; (10) Previous exposure to levothyroxine, desiccated thyroid, or T3 preparations; (11) Participation in another clinical trial that could interfere with this study.

• RESULTTurner, H.L., van Etten, J., Firth, D. et al. Modelling rankings in R: the PlackettLuce package. Computational Statistics.2020; 35(3): 1027-1057.
• RESULTFussey JM, Khan H, Ahsan F, Prashant R, Pettit L. Thyroid-stimulating hormone suppression therapy for differentiated thyroid cancer: The role for a combined T3/T4 approach. Head Neck. 2017 Dec;39(12):2567-2572. doi: 10.1002/hed.24926. Epub 2017 Sep 27. PMID 28960722
• RESULTHao D, Tian L, He H, Zhu C, Guo L, Zhang K, Zhang J. Efficacy and safety of postoperative levothyroxine sodium tablets for improving serum thyroid hormone levels and tumor marker levels in patients with thyroid tumors. Eur J Transl Myol. 2023 Sep 5;33(3):11582. doi: 10.4081/ejtm.2023.11582. PMID 37668013
• RESULTWang Z, Angell TE, Sun W, Qin Y, He L, Dong W, Zhang D, Zhang T, Shao L, Lv C, Zhang P, Guan H, Zhang H. Analysis of the strategy of LT4 prescribing and TSH monitoring for thyroid carcinoma after lobectomy. Ann Transl Med. 2020 Oct;8(19):1238. doi: 10.21037/atm-20-4890. PMID 33178770
• RESULTChen W, Li J, Peng S, Hong S, Xu H, Lin B, Liang X, Liu Y, Liang J, Zhang Z, Ye Y, Liu F, Lin C, Xiao H, Lv W. Association of Total Thyroidectomy or Thyroid Lobectomy With the Quality of Life in Patients With Differentiated Thyroid Cancer With Low to Intermediate Risk of Recurrence. JAMA Surg. 2022 Mar 1;157(3):200-209. doi: 10.1001/jamasurg.2021.6442. PMID 34935859
• RESULTMing J, Zhu JQ, Zhang H, Sun H, Wang J, Cheng RC, Xie L, Li XR, Tian W, Huang T. A multicenter, prospective study to observe the initial management of patients with differentiated thyroid cancer in China (DTCC study). BMC Endocr Disord. 2021 Oct 21;21(1):208. doi: 10.1186/s12902-021-00871-x. PMID 34670546
• RESULTYavuz DG, Yazan CD, Hekimsoy Z, Aydin K, Gokkaya N, Ersoy C, Akalin A, Topaloglu O, Aydogan BI, Dilekci ENA, Alphan Uc Z, Cansu GB, Ozsari L, Iyidir OT, Olgun ME, Keskin L, Mert M, Can B, Gungor K, Galip T, Canturk Z, Elbuken G, Pekkolay Z, Kutbay NO, Yorulmaz G, Kalkan AT, Unsal YA, Yay A, Karagun B, Bozkur E. Assesment of attainment of recommended TSH levels and levothyroxine compliance in differentiated thyroid cancer patients. Clin Endocrinol (Oxf). 2022 Dec;97(6):833-840. doi: 10.1111/cen.14787. Epub 2022 Jun 12.