Simultaneous Measurement of Total and Free Triiodothyronine and Thyroxine in Human Serum
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概要
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The method of simultaneous measurement of total triiodothyronine (T<SUB>3</SUB>) and thyroxine (T<SUB>4</SUB>) in serum has been developed by modifying Sterlings method. More sensitive standard curve was obtained by using Sephadex-charcoal mixture to separate free from bound form, where only one or two m<I>l</I> of serum is required. Also the method of simultaneous measurement of free T<SUB>3</SUB> and T<SUB>4</SUB> was described on the basis of the fact that dialyzate of free T3 could be completely precipitated in the same way as the measurement of free T<SUB>4</SUB>. Dialyzable fraction of T<SUB>3</SUB> (DFT<SUB>3</SUB>) and DFT<SUB>4</SUB> have become simultaneously obtainable by using <SUP>125</SUP>I-T<SUB>3</SUB> and <SUP>131</SUP>I-T<SUB>4</SUB> resulting in saving time and serum.<BR>Total T<SUB>3</SUB> and total T<SUB>4</SUB> values (mean±SD) were respectively, 0.31±0.12, 7.5±1.0μg per 100m<I>l</I> in normal, 0.73±0.15, 19.0±2.9μg per 100ml in hyperthyroid, and 0.14±0.06, 1.3±0.4μg per 100ml in hypothyroid. The respective values (mean±SD) for DFT<SUB>3</SUB> and DFT<SUB>4</SUB> were 0.53±0.17, 0.044±0.015% in normal, 1.19±0.63, 0.092± 0.031% in hyperthyroid and 0.23±0.04, 0.028±0.006% in hypothyroid. Percentage of DFT<SUB>3</SUB> was approximately ten times as high as that of DFT<SUB>4</SUB> in each thyroid state.<BR>The respective values (mean±SD) for the absolute concentration of free T<SUB>3</SUB> (AFT3) and AFT<SUB>4</SUB> were 2.21±0.90, 3.60±0.32 mμg per 100ml in normal, 6.70±2.60, 19.6±3.8 mpg per 100ml in hyperthyroid and 0.36±0.04, 0.35±0.02 mpg per 100 m<I>l</I> in hypothyroid. Total T<SUB>3</SUB> is minimal as compared with total T<SUB>4</SUB>, but AFT<SUB>3</SUB> is not so different from AFT<SUB>4</SUB>.<BR>The ratios of total T<SUB>3</SUB> to total T<SUB>4</SUB> and of AFT<SUB>3</SUB> to AFT<SUB>4</SUB> were 0.053±0.012, 0.67± 0.31 in normal, 0.037±0.004, 0.44±0.14 in hyperthyroid and 0.119±0.073, 1.10± 0.67 in hypothyroid.<BR>These ratios increased along with the decrease of thyroid hormone in serum, which suggests that the less are thyroid hormones in serum the more important is T<SUB>3</SUB>.<BR>From these data and kinetic study indicating degradation rate of 51μg per day for T<SUB>3</SUB> and 75μg per day for T<SUB>4</SUB>, the physiological meaning of T<SUB>3</SUB> may be more important in health and diseases than considered before.
- 社団法人 日本内分泌学会の論文