Soppi E, Irjala K, Kaihola H L, Viikari J
Scand J Clin Lab Invest. 1984 Jun;44(4):353-6. doi: 10.3109/00365518409083819.
Acute effects of exogenous thyroxine on the serum thyroxine (T4), free thyroxine (FT4) and thyrotrophin (TSH) levels were studied in 20 hypothyroid women during the long-term maintenance therapy. All patients were euthyroid by clinical and laboratory parameters (T4). In nine patients TSH secretion was totally suppressed (less than 1 mu/l) by the mean dose of 178 micrograms thyroxine. Eleven patients had TSH values greater than 1 mu/l. Their mean thyroxine dose (132 micrograms) was not significantly lower than that which totally suppressed the TSH secretion. Ingestion of thyroxine resulted in maximal T4 and FT4 levels at 2 h after taking the drug. Simultaneously TSH concentration reached its minimum. The results indicate that it is necessary to know when the patient has taken the thyroxine in relation to determination of T4, FT4 and TSH levels in order to make the right decisions about the substitution dose of thyroxine. Thus it is essential to take blood sample for hormone determination before the patient ingests the daily thyroxine dose. However, among hypothyroid patients substituted by thyroxine there are individuals whose TSH secretion is not suppressed by normal T4 and FT4 levels.
在20名接受长期维持治疗的甲状腺功能减退女性中，研究了外源性甲状腺素对血清甲状腺素（T4）、游离甲状腺素（FT4）和促甲状腺激素（TSH）水平的急性影响。根据临床和实验室参数（T4），所有患者的甲状腺功能均正常。9名患者的促甲状腺激素分泌被平均剂量为178微克的甲状腺素完全抑制（低于1μl）。11名患者的促甲状腺激素值大于1μl。他们的平均甲状腺素剂量（132微克）并不显著低于完全抑制促甲状腺激素分泌的剂量。服用甲状腺素后2小时，T4和FT4水平达到最高。同时，促甲状腺激素浓度降至最低。结果表明，在测定T4、FT4和TSH水平时，有必要了解患者服用甲状腺素的时间，以便对甲状腺素替代剂量做出正确决策。因此，必须在患者服用每日甲状腺素剂量之前采集血样进行激素测定。然而，在接受甲状腺素替代治疗的甲状腺功能减退患者中，有一些人的促甲状腺激素分泌不会被正常的T4和FT4水平所抑制。
