Profile of Levothyroxine Replacement Therapy in Graves’ Disease Patients with Hypothyroidism Post-Radioactive Iodine Ablation Focus on Different Weight-Based Regimens

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Saravut Mathiphanit
Nalin Yenseung
Waralee Chatchomchuan
Siriwan Butadej
Soontaree Nakasatien
Ekgaluck Wanothayaroj
Rajata Rajatanavin
Thep Himathongkam
Yotsapon Thewjitcharoen


Objective. To evaluate the status of euthyroidism achieved among Thai patients with post-ablative hypothyroidism and to examine the difference between various weight-based daily levothyroxine (LT4) replacement regimens in these patients.

Methodology. We conducted a retrospective review of Thai patients with Graves’ disease (GD) who developed hypothyroidism following radioactive iodine treatment from 2016  to 2020 at Theptarin hospital. Daily LT4 dose was calculated based on actual body weight (ABW), ideal body weight (IBW), and estimated lean body mass (LBM).

Results. We reviewed a total of 271 patient records. Of these, 81.2% were females with a mean age of 40.8±11.7 years, LT4 intake duration of 27.1±14.6 months, and LT4 dose/kg ABW of 1.4±0.5 μg/kg/day. At the final follow-up, 62.4% of patients achieved thyroid-stimulating hormone (TSH) levels within the reference interval, 15.5% had TSH levels over, and 22.1% had TSH levels under the reference range. Obese patients required a lower daily LT4 dose relative to ABW and higher daily LT4 dose relative to IBW to attain euthyroidism (ABW 1.1±0.4 μg/kg/day and IBW 2.0±0.8 μg/kg/day). Estimated daily LT4 dose based on LBM showed a constant dosage of 2.0 μg/kg/day in all BMI categories.  

Conclusions. Suboptimum LT4 replacement therapy was found in almost half of hypothyroid patients with GD treated with radioactive iodine. Estimated LBM was a better indicator for dosing calculation in these patients compared with ABW and IBW.


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How to Cite
Mathiphanit, S. ., Yenseung, N. ., Chatchomchuan, W., Butadej, S., Nakasatien, S., Wanothayaroj, E., Rajatanavin, R. ., Himathongkam, T., & Thewjitcharoen, Y. (2022). Profile of Levothyroxine Replacement Therapy in Graves’ Disease Patients with Hypothyroidism Post-Radioactive Iodine Ablation: Focus on Different Weight-Based Regimens. Journal of the ASEAN Federation of Endocrine Societies, 37(1), 62–68.
Original Articles
Author Biographies

Saravut Mathiphanit, Diabetes and Thyroid Center, Theptarin Hospital, Bangkok, Thailand


Nalin Yenseung, Diabetes and Thyroid Center, Theptarin Hospital, Bangkok, Thailand


Waralee Chatchomchuan, Diabetes and Thyroid Center, Theptarin Hospital, Bangkok, Thailand


Siriwan Butadej, Diabetes and Thyroid Center, Theptarin Hospital, Bangkok, Thailand

Research Nurse

Ekgaluck Wanothayaroj, Diabetes and Thyroid Center, Theptarin Hospital, Bangkok, Thailand


Rajata Rajatanavin, Diabetes and Thyroid Center, Theptarin Hospital, Bangkok, Thailand


Thep Himathongkam, Diabetes and Thyroid Center, Theptarin Hospital, Bangkok, Thailand


Yotsapon Thewjitcharoen, Diabetes and Thyroid Center, Theptarin Hospital, Bangkok, Thailand



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