Benvenga Salvatore, Di Bari Flavia, Vita Roberto
Department of Clinical and Experimental Medicine, University of Messina, Viale Gazzi,, 98125, Messina, Italy.
Master Program on Childhood, Adolescent and Women's Endocrine Health, University of Messina, Viale Gazzi,, 98125, Messina, Italy.
Endocrine. 2017 Apr;56(1):138-145. doi: 10.1007/s12020-017-1244-2. Epub 2017 Feb 3.
The aim of this study was to assess whether oral liquid levothyroxine would correct tablet levothyroxine malabsorption induced by calcium or iron, two sequestrants of levothyroxine.
Nineteen adult hypothyroid patients with tablet levothyroxine malabsorption caused by calcium and/or iron supplements were switched from tablet to liquid levothyroxine at the same dose. Primary outcomes were: (1) significantly lower mean serum thyroid-stimulating hormone with the liquid compared with the tablet formulation, and (2) significantly greater rate of serum thyroid-stimulating hormone less than or equal to 4.12 or 2.5 mU/L.The mean follow-up was 25.2 ± 16.5 weeks.
TSH was lower with liquid levothyroxine compared with tablet levothyroxine (7.48 ± 5.8 vs. 1.95 ± 1.3 mU/L, P < 0.001), both in the calcium group (8.74 ± 7.2 vs. 2.15 ± 1.4, P < 0.001) and iron group (8.74 ± 7.2 vs. 1.68 ± 0.9, P < 0.001). Thyroid-stimulating hormone levels ≤4.12 mU/L in all patients, calcium group and iron group were more frequent post-switch (95, 87 and 100%) compared to pre-switch (26, 22 and 29%, P < 0.001), and so were thyroid-stimulating hormone levels ≤2.50 mU/L (66, 59 and 76% compared to 5, 9 and 0%, P < 0.001). The pattern held comparing the first liquid levothyroxine thyroid-stimulating hormone levels and the first tablet levothyroxine thyroid-stimulating hormone levels or the corresponding rates of thyroid-stimulating hormone levels below the target.
Liquid levothyroxine is resistant to the sequestration by calcium or iron. The high rate of thyroid-stimulating hormone normalization already at the first check (6-8 weeks) should avoid frequent adjustments in levothyroxine doses and assays of thyroid-stimulating hormone, with consequent financial savings.
本研究旨在评估口服液体左甲状腺素是否能纠正由钙或铁（两种左甲状腺素螯合剂）引起的左甲状腺素片吸收不良。
19例因补充钙和/或铁导致左甲状腺素片吸收不良的成年甲状腺功能减退患者，以相同剂量从左甲状腺素片转换为液体左甲状腺素。主要结局为：（1）与片剂相比，液体剂型的平均血清促甲状腺激素显著降低；（2）血清促甲状腺激素水平小于或等于4.12或2.5 mU/L的发生率显著更高。平均随访时间为25.2±16.5周。
与左甲状腺素片相比，液体左甲状腺素的促甲状腺激素水平更低（7.48±5.8对1.95±1.3 mU/L，P<0.001），在钙组（8.74±7.2对2.15±1.4，P<0.001）和铁组（8.74±7.2对1.68±0.9，P<0.001）中均如此。转换后，所有患者、钙组和铁组促甲状腺激素水平≤4.12 mU/L的情况比转换前更频繁（分别为95%、87%和100%对26%、22%和29%，P<0.001），促甲状腺激素水平≤2.50 mU/L的情况也是如此（分别为66%、59%和76%对5%、9%和0%，P<0.001）。比较首次液体左甲状腺素促甲状腺激素水平与首次左甲状腺素片促甲状腺激素水平或低于目标值的促甲状腺激素水平相应发生率时，该模式依然成立。
液体左甲状腺素对钙或铁的螯合具有抗性。首次检查（6 - 8周）时促甲状腺激素正常化率很高，应避免频繁调整左甲状腺素剂量和促甲状腺激素检测，从而节省费用。
