Pinchera A, Ambrosino N, Mammoli C
Ann Ist Super Sanita. 1975;11(1-2):45-60.
The value of measurements of serum thyroxine (T4) and triiodothyronine (T3) concentrations in the clinical evaluation of thyroid function is well established. In the present report the properties of the methods currently available for the assessment of circulating thyroid hormones are examined. Recent data indicate that results of measurements of serum T4 by radioimmunoassay (RIA) or by displacement analysis are qualitatively and quantitatively similar. Evidence has been provided from this and other laboratories that elevated or subnormal serum levels of total tt4 may be observed in several euthyroid physiologicmal serum levels of total T4 may be observed in several euthyroid physiological or pathological conditions associated with altered capacity of the thyroxine-binding protein; in these cases a normal free thyroxine index is usually found indicating its importance in the evaluation of thyroid function. Several physiological observations and the recent recognition of clinical conditions associated with changes in the T4/T3 ratio, justify the present interest in the measurement of serum T3. The advantages of RIA methods with respect to displacement techniques in the determination of this hormone are well documented. The AA. report here their experience with a simple RIA method for total T3, using a single Sephadex G25 column for extraction of T3 from serum and for separation of bound from free hormone. The mean (+/-SD) values of serum T3 found in 78 normal, 23 hyperthyroid and 25 hypothyroid subjects were as follows:160+/37ng/dl, 604+/195ng/dl and 35+/23ng/dl respectively. High values were found in 19 pregnant women at delivery (236+/29ng/dl), but not in 5 subjects on contraceptives (156+/42ng/dl). A relatively large variability is noted when normal values reported from different laboratories are compared. This may be related at least in part to geographical and/or ethnical factors, but methodolgical differences may also be involved. The normal range of circulating T3 should be established in each individual laboratory.
血清甲状腺素（T4）和三碘甲状腺原氨酸（T3）浓度测定在甲状腺功能临床评估中的价值已得到充分确立。在本报告中，对目前可用于评估循环甲状腺激素的方法的特性进行了研究。最近的数据表明，通过放射免疫分析（RIA）或置换分析测定血清T4的结果在定性和定量上是相似的。本实验室及其他实验室已提供证据表明，在几种甲状腺功能正常的生理或病理情况下，当甲状腺素结合蛋白结合能力改变时，可能会观察到血清总T4水平升高或低于正常水平；在这些情况下，通常会发现游离甲状腺素指数正常，这表明其在评估甲状腺功能中的重要性。一些生理学观察以及最近对与T4/T3比值变化相关的临床情况的认识，证明了目前对血清T3测定的关注是合理的。在测定这种激素时，RIA方法相对于置换技术的优势已得到充分证明。作者在此报告了他们使用一种简单的RIA方法测定总T3的经验，该方法使用单个Sephadex G25柱从血清中提取T3并分离结合型和游离型激素。在78名正常受试者、23名甲状腺功能亢进受试者和25名甲状腺功能减退受试者中发现的血清T3平均（±标准差）值如下：分别为160±37ng/dl、604±195ng/dl和35±23ng/dl。在19名分娩时的孕妇中发现T3值较高（236±29ng/dl），但在5名服用避孕药的受试者中未发现（156±42ng/dl）。当比较不同实验室报告的正常数值时，会注意到相对较大的变异性。这可能至少部分与地理和/或种族因素有关，但也可能涉及方法学差异。每个实验室都应确定循环T3的正常范围。
