Japanese
Title標識抗T4モノクローナル抗体を用いた血中FT4の測定
Subtitle技術報告
Authors池窪勝治*, 才木康彦*, 太田圭子*, 石川昌子*, 山口晴司*, 伊藤秀臣*, 日野恵*, 服部尚樹**, 石原隆**, 森寺邦三郎**, 倉八博之**
Authors(kana)
Organization*神戸市立中央市民病院核医学科, **内分泌内科
Journal核医学
Volume31
Number4
Page379-392
Year/Month1994/4
Article報告
Publisher日本核医学会
Abstract「要旨」 標識抗T4抗体を用いる1ステップ法FT4ラジオアッセイ (Amerlex-MAB FT4) について標識T4誘導体によるラジオイムノアッセイ (Amerlex-M FT4) と比較検討した. 本測定法は37℃, 30分の反応時間で, 迅速かつ簡便に測定でき, 精度および再現性は良好であった. Amerlex-M FT4では血清アルブミンおよびT4自己抗体の影響を強く受けるのに反し本法ではほとんど認められなかった. 本法によるFT4の正常域は0.99〜1.54 ng/dlであり, 甲状腺機能正常, 亢進症および低下症の分離は良好であった. 正常妊婦におけるFT4値は妊娠初期に比べて中期および後期で若干低値を示したが, 血清アルブミンやTBG濃度の変化による測定上の問題ではなく, 生理的な変動と考えられた. 以上より, 本法によるFT4の測定は, 甲状腺機能を知る上で臨床上きわめて有用であると考えられた.
Practice臨床医学：一般
KeywordsRadiolabeled antibody radioassay, Analog tracer RIA, Amerlex-MAB FT4, Amerlex-M FT4, Serum albumin concentrations.
English
TitleMeasurement of Serum Free Thyroxine Concentrations Using anti-T4 Monoclonal Antibody
SubtitleTechnical Report
AuthorsKatsuji IKEKUBO*, Yasuhiko SAIKI*, Keiko OHTA*, Masako ISHIKAWA*, Haruji YAMAGUCHI*, Hidetomi ITO*, Megumu HINO*, Naoki HATTORI**, Takashi ISHIHARA**, Kunisaburo MORIDERA**, Hiroyuki KURAHACHI**
Authors(kana)
Organization*Department of Nuclear Medicine, **Department of Internal Medicine, Kobe City General Hospital
JournalThe Japanese Journal of nuclear medicine
Volume31
Number4
Page379-392
Year/Month1994/4
ArticleReport
PublisherTHE JAPANESE SOCIETY OF NUCLEAR MEDICINE
Abstract[Summary] A new one-step radiolabeled antibody radioassay for measuring free T4 (FT4) in serum (Amerlex-MAB FT4) was evaluated in comparison with an analog tracer RIA of FT4 (Amerlex-M FT4) . In this new method, 125I-labeled anti-T4 monoclonal antibody which has cross-reactivity with T3 is used as a tracer. When incubated with serum sample, the tracer binds to FT4 and the remaining tracer binds to a T3 coated particle (Amerlex MAB) . The radioactivity bound to Amerlex MAB is measured. Counts of 125I bound to the T3 coated particle were inversely proportional to sample FT4 concentrations. The assay procedure is as follows. Fifty microliter of patient's serum or standard FT4, 500 μl of Amerlex MAB and tracer is incubated at 37℃ for 30 minutes and centrifuged. Then the radioactivity of Amerlex MAB is measured using an autowell gamma counter. The intra- and interassay coefficients of variation were 1.6-2.7% and 2.6-8.0%, respectively. Although Amerlex-M FT4 values were significantly increased by adding human albumin to the serum, Amerlex-MAB FT4 values were not effected by the change of albumin concentrations. In nonthyroidal illness patients, Amerlex-MAB FT4 values were not affected by the concentrations of albumin, TBG and NEFA. The euthyroid central 95% reference range for FT4 determined by Amerlex-MAB FT4 was 0.99 to 1.54 ng/dl. The FT4 levels correlated well with the metabolic status. Although Amerlex-M FT4 values were spuriously increased in patients with anti-T4 autoantibodies, Amerlex-MAB FT4 values were not affected by the autoantibodies. Amerlex-MAB FT4 values of normal pregnant women were slightly lower in the second and third trimesters than in the first trimester. These lower FT4 concentrations in late pregnancy were considered likely not to be artefact by low serum albumin or high serum TBG but to be a physiological event. Amerlex-MAB FT4 values correlated well with FT4 indices and inversely correlated with TSH levels. A significant correlation (n=401, r=0.86, p=0.0001) was observed between Amerlex-MAB FT4 and Amerlex-M FT4 values in various thyroid conditions without antithyroid autoantibodies. In summary, this new assay for FT4 is simple, rapid and reproducible The measurement is useful for the evaluation of physiological thyroid function and helpful in the management of patients with thyroid diseases.
PracticeClinical medicine
KeywordsRadiolabeled antibody radioassay, Analog tracer RIA, Amerlex-MAB FT4, Amerlex-M FT4, Serum albumin concentrations.

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