Japanese
Title低蛋白血症におけるfree T4 RIA測定値の信頼性に関する検討
Subtitle原著
Authors松村要*, 中川毅*, 信田憲行**, 服部孝雄*, 奥田康之*, 田口光雄*, 山口信夫*
Authors(kana)
Organization*三重大学医学部放射線科, **附属病院中央放射線部
Journal核医学
Volume22
Number4
Page511-520
Year/Month1985/4
Article原著
Publisher日本核医学会
Abstract「要旨」血清蛋白に変動のある症例におけるfree T4 RIA測定値の信頼性を検討するため, 4種のRIAキット [GammaCoat 2-step法 (GC−2) , LiquiSol (LS) , Amerlex (AM) , GammaCoat 1-step法 (GC-1) ] を用いて, 低蛋白, 低アルブミン血症の老人19人の血中free T4値を測定した. 透析法によるfree T4値は正常域に分布し, これらが正常甲状腺機能であることを示した. LSによるfree T4値はTBG低下群のみ著しく有意の低値 (P<0.001) となり, TBG濃度の測定値への影響が疑われ, AMとGC-1は, TEG正常群, 低下群ともに有意の低値 (P<0.01〜0.001) となり, アルブミン濃度の測定値への影響が疑われた. LS, AM, GC-1では検体量を減少させるとB/B0は増加し, 同様の変化がホルモンフリー血清でも見られ, 低蛋白血症血清にTBG, アルブミンを添加して正常濃度とすると, free T4値も正常域に復したことから, TBG, アルブミンとトレーサーの結合反応が測定値に影響すると考えた. しかし, GC-2はこのような変動が見られず, 測定値も正常域に分布し, 透析法による値と良好な相関を示した (r=0.80, p<0.001).
Practice臨床医学：一般
KeywordsRadioimmunoassay, Free T4, Hypoproteinemia, TBG
English
TitleEvaluation of Free Thyroxine Radioimmunoassays for Assessing Thyroid Function in Hypoproteinemia
Subtitle
AuthorsKaname MATSUMURA*, Tsuyoshi NAKAGAWA*, Noriyuki SHINODA**, Takao HATTORI*, Yasuyuki OKUDA*, Mitsuo TAGUCHI*, Nobuo YAMAGUCHI*
Authors(kana)
Organization*Department of Radiology, Mie University Medical School, **Central Clinical Division of Radiology, Mie University Hospital
JournalThe Japanese Journal of nuclear medicine
Volume22
Number4
Page511-520
Year/Month1985/4
ArticleOriginal article
PublisherTHE JAPANESE SOCIETY OF NUCLEAR MEDICINE
Abstract[Summary] Four commercial free T4 RIA kits [Gamma-Coat by the two-step method (GC-2) , Gamma-Coat by the one-step method (GC-1) , LiquiSol (LS) and Amerlex (AM) ] were evaluated both from clinical data in hypoproteinemia and binding reactions in the assay systems in comparison with equilibrium dialysis. Sera were obtained from 19 geriatric inpatients with hypoalbuminemia due to malnutrition. These patients were divided into two groups, A in which serum total T4 was less than 6μg/dl (8 cases) and group B in which total T4 was 6μg/dl or more (11 cases) . The serum TBG concentration of group A was significantly decreased (p<0.001) while that in group B was within normal limits. The free T4 values by equilibrium dialysis were within normal limits in both groups, supporting these patients were euthyroidism. The free T4 values by GC-2 were consistently within normal limits in both groups. The free T4 values by LS in group B were within normal limits while those in group A were significantly decreased (p<0.001) .There was a significant correlation between the free T4 values by LS and the TBG concentrations (r=0.64, p<0.01) . Thus the free T4 value by LS RIA was considered to be affected by the TBG concentration. The free T4 values by AM were significantly decreased in both group A and B (p<0.001, p<0.01, respectively) and those by GC-1 were also significantly decreased in both groups (both p<0.001) . There was a significant correlation between free T4 values by AM and by GC-1 and the serum albumin concentrations (r=0.52, p<0.05 and r=0.74, p<0.001, respectively) . In these two methods, the free T4 value was considered to be affected by the serum albumin concentration. The effect of the serum TBG and albumin concentrations in these kits was, by an experiment, further confirmed to be within normal range after correction of the protein concentrations. The effect of a sample volume on the value for free T4 was evaluated in 4 RIA kits. The value was constant in all sera in GC-2 RIA, as predicted by mass law equation, while it changed in response to a sample volume in the other 3 RIA kits. From the fact that the changes in patient sera were similar to those in hormone free serum, it was concluded that the binding of tracer by TBG and albumin was the cause of the abnormal value in hypoproteinemia.
PracticeClinical medicine
KeywordsRadioimmunoassay, Free T4, Hypoproteinemia, TBG

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