Rootwelt K, Ganes T, Johannessen S I
Scand J Clin Lab Invest. 1978 Dec;38(8):731-6. doi: 10.3109/00365517809104880.
Patients on long-term treatment with either of the stereochemically related antiepileptic drugs phenytoin (DPH) or carbamazepine (CBZ) had similar changes in serum thyroid hormone concentrations. T4, FT4, FT4 index, T3, FT3, FT3 index and rT3 were reduced, whereas T3U and TSH were not significantly different from the reference group levels. Long-term phenobarbitone treatment had no convincing effect on the investigated parameters when used alone, but possibly potentiated the effect of CBZ. In patients starting on CBZ, T4 fell to a stable 70% of the basal level after 1--2 weeks. T3 decreased transitorily to 85% of the basal level. TSH showed a complementary but somewhat delayed transitory increase. T3U and TBG did not change significantly. The effect of CBZ and DPH can be explained by interference with thyroid hormone binding to TBG combined with enzyme-induced increased metabolic clearance rate of thyroid hormones without homeostatic maintenance of premedication levels of FT4 and FT3. We suggest that the regulated factor maintaining euthyroidism in these patients is the total quantity of thyroid hormones being degraded in the tissues per unit time. We conclude that serum concentrations of FT4 and FT3 do not reflect thyroid status adequately under all circumstances.
长期接受立体化学相关抗癫痫药物苯妥英（DPH）或卡马西平（CBZ）治疗的患者，其血清甲状腺激素浓度变化相似。T4、游离T4（FT4）、FT4指数、T3、游离T3（FT3）、FT3指数及反三碘甲状腺原氨酸（rT3）降低，而甲状腺素结合球蛋白（T3U）和促甲状腺激素（TSH）与参照组水平无显著差异。单独使用长效苯巴比妥治疗对所研究参数无明显影响，但可能增强了卡马西平的作用。开始服用卡马西平的患者，1 - 2周后T4降至基础水平的70%并稳定下来。T3短暂降至基础水平的85%。TSH呈互补性但稍有延迟的短暂升高。T3U和甲状腺素结合球蛋白（TBG）无显著变化。卡马西平和苯妥英的作用可解释为干扰甲状腺激素与TBG的结合，同时酶诱导甲状腺激素代谢清除率增加，而FT4和FT3的用药前水平未通过体内平衡维持。我们认为，维持这些患者甲状腺功能正常的调节因素是单位时间内组织中降解的甲状腺激素总量。我们得出结论，在所有情况下，FT4和FT3的血清浓度都不能充分反映甲状腺状态。
