Levothyroxine liquid solution versus tablet form for replacement treatment in pregnant women

Abstract

Objective: To evaluate the need and the magnitude of levothyroxine (LT4) increase in hypothyroid pregnant women on liquid compared to tablet formulations.

Methods: Patients were recruited by searching our “thyroid patients” database. The selection criteria were as follows: a) pregnant women on treatment for hypothyroidism (both liquid and tablet LT4) who gave birth at our hospital between February 2012 and January 2014; b) thyroid stimulating hormone (TSH) and free thyroxine (FT4) levels obtained at least 3 months before missed menstrual cycle, with a TSH value less than 2.5 mIU/L and c) TSH and FT4 obtained within 12 weeks of pregnancy, and each month subsequently.

Results: During pregnancy, 8/31 (25.5%) of the women had to increase the dosage of LT4. Of these, 7/17 (41.2%) were on LT4 replacement therapy with tablets, and 1/14 (7.1%) with liquid formulation (p = 0.038). Daily LT4 was significantly increased in the liquid group only (52.9 ± 19.5 versus 67.5 ± 19.2 mcg/day (p = 0.013). A logistic regression analysis showed that the treatment with LT4 tablets was the only predictor of LT4 increase (OR: 0.44; 95% CI: 0.04–0.83; p = 0.031).

Conclusion: Pregnant women on optimal replacement therapy before pregnancy require an increase of LT4 dosage more often when on a tablet than liquid formulation.

Chinese abstract

目的：评估相比于采用左旋甲状腺素（LT4）片剂替代疗法，甲状腺功能减退孕妇采用左旋甲状腺激素液替代疗法时需要增加的左旋甲状腺素剂量及必要性。

方法：患者选自我院“甲状腺相关疾病患者”数据库。入选标准：a)选取2012年2月∼2014年1月之间在我院分娩的正在进行甲减治疗（LT4液和片剂）的孕妇作为观察组；b）获得非经期的至少三个月前的促甲状腺激素(TSH)和游离甲状腺素（FT4）水平，且TSH低于2.5 mIU/L c)获得怀孕12周内以及接下来每个月的TSH和FT4水平。

结果：孕期8/31 (25.5%)孕妇需要增加LT4的服用剂量。这其中7/17 (41.2%)孕妇采用片剂LT4替代疗法，1/14 (7.1%)采用LT4液替代疗法(p=0.038)。LT4液组日LT4需要的增加量为(52.9 ± 19.5 versus 67.5 ± 19.2 mcg/day (p=0.013)。逻辑回归分析表明：LT4片剂疗法是LT4需求增加的唯一预测指标(OR: 0.44; 95% CI: 0.04–0.83; p=0.031)。

结论：孕妇进行激素替代治疗时，相比于采用LT4液，采用LT4片剂替代疗法时更需要增加LT4的剂量。

• Hypothyroidism
• levothyroxine
• liquid solution
• pregnant women

Declaration of interest

The authors have no conflicts of interest to declare.