Brown M E, Refetoff S
Ann Intern Med. 1980 Apr;92(4):491-5. doi: 10.7326/0003-4819-92-4-491.
Measurements of thyroid hormone concentrations in serum are commonly used to determine the proper dose of hormone replacement. We have noted that early in the course of thyroxine (T4) replacement in myxedema, serum T4 concentrations may be transiently elevated before reaching a lower "steady-state" level. This observation is illustrated in a study of six patients. Serum T4, free thyroxine index, and triiodothyronine (T3) rose to peak concentrations at 2 to 6 weeks, 35% to 120% above the values achieved 4 to 8 months later. Values were transiently in the thyrotoxic range in five of the six patients. This phenomenon is most likely due to a decrease in the metabolic clearance rate of the absorbed hormone associated with hypometabolism. Thus, serum T4 and T3 concentrations during the first 6 months of therapy do not reflect the optimal dose of T4 replacement on a long-term basis.
血清甲状腺激素浓度的测量常用于确定激素替代治疗的合适剂量。我们注意到，在黏液性水肿患者进行甲状腺素（T4）替代治疗的早期，血清T4浓度在达到较低的“稳态”水平之前可能会短暂升高。一项对6名患者的研究说明了这一观察结果。血清T4、游离甲状腺素指数和三碘甲状腺原氨酸（T3）在2至6周时升至峰值浓度，比4至8个月后达到的值高出35%至120%。6名患者中有5名的数值曾短暂处于甲状腺毒症范围内。这种现象很可能是由于与代谢减退相关的吸收激素代谢清除率降低所致。因此，治疗前6个月的血清T4和T3浓度并不能长期反映T4替代治疗的最佳剂量。
