Ratanapornsompong Ganista, Sriphrapradang Chutintorn
Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand.
J Clin Transl Endocrinol. 2021 Jul 30;25:100264. doi: 10.1016/j.jcte.2021.100264. eCollection 2021 Sep.
Athyreotic patients require a daily levothyroxine (LT4) doses of 1.6-1.8 mcg/kg of actual body weight (BW) to achieve normal thyroid stimulating hormone (TSH) levels. Lean body mass (LBM) calculation may be a more accurate determination of LT4 dose in obese patients. Previous studies were mainly investigated in Caucasians and LBM is markedly different between various ethnic groups. We aim to identify the optimal dose of LT4 replacement therapy in hypothyroid Thai patients including obese subjects.
We retrospectively reviewed the medical records of Thai adults with hypothyroidism at the thyroid clinic. Patients had been received LT4 (Brand: Euthyrox) at a stable dose ≥ 75 mcg/day for at least 1 year. Patients with thyroid cancer, pregnant, and lactating women were excluded. LBM was calculated by the Hume formula.
Two hundred patients (80% females) with a mean age of 48.6 ± 14.8 years and a body mass index (BMI) of 24.5 ± 4.6 kg/m were included. Daily LT4 dose/kg of actual BW according to BMI 18.5-24.9, 25-29.9, and ≥ 30 kg/m were 1.67 ± 0.27, 1.51 ± 0.28 and 1.39 ± 0.34 mcg/kg, respectively. In contrast, LT4 dose/kg of LBM were 2.31 ± 0.39, 2.35 ± 0.45 and 2.36 ± 0.51 mcg/kg, respectively.
LBM is considered a better indicator for calculating an appropriate LT4 replacement dose than actual BW in hypothyroid obese Thai patients. The recommended daily dose of LT4 is 2.3 mcg/kg of LBM that could be applied for all ranges of BMI.
甲状腺功能减退患者需要每日服用1.6 - 1.8微克/千克实际体重（BW）的左甲状腺素（LT4），以达到正常的促甲状腺激素（TSH）水平。瘦体重（LBM）计算可能是确定肥胖患者LT4剂量的更准确方法。以往研究主要针对高加索人，且不同种族间的LBM存在显著差异。我们旨在确定甲状腺功能减退的泰国患者（包括肥胖患者）LT4替代治疗的最佳剂量。
我们回顾性分析了甲状腺门诊泰国成年甲状腺功能减退患者的病历。患者接受稳定剂量≥75微克/天的LT4（品牌：优甲乐）治疗至少1年。排除甲状腺癌患者、孕妇和哺乳期妇女。LBM通过休谟公式计算。
纳入200例患者（80%为女性），平均年龄48.6±14.8岁，体重指数（BMI）为24.5±4.6千克/平方米。根据BMI 18.5 - 24.9、25 - 29.9和≥30千克/平方米，每日LT4剂量/千克实际体重分别为1.67±0.27、1.51±0.28和1.39±0.34微克/千克。相比之下，每日LT4剂量/千克LBM分别为2.31±0.39、2.35±0.45和2.36±0.51微克/千克。
对于甲状腺功能减退的肥胖泰国患者，LBM被认为是比实际体重更好的计算合适LT4替代剂量的指标。LT4的推荐日剂量为2.3微克/千克LBM，可应用于所有BMI范围。
