Tamaki H, Amino N, Takeoka K, Mitsuda N, Miyai K, Tanizawa O
Department of Laboratory Medicine, Osaka University Medical School, Japan.
Obstet Gynecol. 1990 Aug;76(2):230-3.
We examined the dose requirements of thyroxine (T4) and desiccated thyroid during eight pregnancies of six women who had undergone total thyroidectomy for thyroid carcinoma. In five pregnancies from four patients treated with T4, serum free T4, which was measured by a newly developed radioimmunoassay, decreased during pregnancy but increased above the normal range after delivery. Consistent with these changes in free T4, serum TSH (measured by a highly sensitive immunoradiometric assay) increased during pregnancy but returned to an undetectable level after delivery, with one exception. The serum triiodothyronine (T3)-to-T4 ratio, which is related to peripheral conversion of T4 to T3, was lower in patients treated with T4 than in normal controls, regardless of pregnancy. The ratio decreased further during pregnancy, and so relative deficiency of T3 during pregnancy was suspected, especially in T4-treated patients. On the other hand, in two pregnancies from two other patients treated with desiccated thyroid at a dose most equivalent to that of T4, serum free T4 decreased to a low-normal value during gestation but returned to the normal range after delivery, whereas serum TSH scarcely changed during pregnancy. These findings indicate that replacement therapy for pregnant patients with hypothyroidism after total thyroidectomy should include an increased dose of T4; in contrast, the dose of desiccated thyroid need not be changed.
我们研究了6名因甲状腺癌接受全甲状腺切除术的女性在8次妊娠期间甲状腺素（T4）和甲状腺干粉的剂量需求。在4名接受T4治疗的患者的5次妊娠中，通过新开发的放射免疫测定法测量的血清游离T4在妊娠期间下降，但产后升至正常范围以上。与游离T4的这些变化一致，血清促甲状腺激素（通过高灵敏度免疫放射测定法测量）在妊娠期间升高，但产后除1例例外均恢复到检测不到的水平。无论是否妊娠，接受T4治疗的患者中与T4向T3外周转化相关的血清三碘甲状腺原氨酸（T3）与T4的比值均低于正常对照组。该比值在妊娠期间进一步下降，因此怀疑妊娠期间尤其是接受T4治疗的患者存在T3相对缺乏。另一方面，在另外2名接受甲状腺干粉治疗且剂量与T4最相当的患者的2次妊娠中，血清游离T4在妊娠期降至低正常水平，但产后恢复到正常范围，而血清促甲状腺激素在妊娠期间几乎没有变化。这些发现表明，全甲状腺切除术后甲状腺功能减退的妊娠患者的替代治疗应增加T4剂量；相比之下，甲状腺干粉的剂量无需改变。
