Caplan R H, Pagliara A S, Wickus G
JAMA. 1980;244(17):1934-8. doi: 10.1001/jama.244.17.1934.
To determine the frequency of thyroxine (T4) toxicosis, we calculated a free triiodothyronine index (FT3I) on 124 patients who displayed elevations of the free T4 index (FT4I) on initial screening. If the clinical presentation was not characteristic of hyperthyroidism or if the FT3I was not elevated, a thyrotropin-releasing hormone (TRH) test was performed. Of 83 hyperthryoid patients, 70 displayed elevations of both the FT4 and FT3 indices. Thirteen patients, however, had elevations of the FT4I alone. This frequency of T4 toxicosis is higher than generally appreciated. Forty-one patients, most of whom were ill with nonthyroidal diseases, had normal TRH test results and were classified euthyroid. We conclude that FT4I elevations owing to T4 toxicosis and nonthyroidal illnesses are common and that the laboratory differentiation between the syndromes may be difficult.
为了确定甲状腺素（T4）中毒的发生率，我们对124例初次筛查时游离T4指数（FT4I）升高的患者计算了游离三碘甲状腺原氨酸指数（FT3I）。如果临床表现不具有甲状腺功能亢进的特征，或者FT3I未升高，则进行促甲状腺激素释放激素（TRH）试验。在83例甲状腺功能亢进患者中，70例FT4和FT3指数均升高。然而，13例患者仅FT4I升高。这种T4中毒的发生率高于普遍认知。41例患者（其中大多数患有非甲状腺疾病）TRH试验结果正常，被归类为甲状腺功能正常。我们得出结论，由T4中毒和非甲状腺疾病导致的FT4I升高很常见，并且这两种综合征在实验室检查中的鉴别可能存在困难。
