Serum 3,3'-L-diiodothyronine, a direct radioimmunoassay in human serum: method and clinical results. [/sup 125/I tracer technique]
A specific radioimmunoassay for 3,3'-diiodothyronine (T/sub 2/) is described which is capable of detecting as little as 1.3 ng/dl. The antiserum recognizes mainly T/sub 2/; biliary conjugates of T/sub 2/ bind slightly to the antibody. The intraassay and interassay coefficients of variation were, respectively, 5.7% and 13.1%. T/sub 2/ was detected in the serum of hypothyroid patients treated with triiodothyronine (T/sub 3/) and in euthyroid subjects treated with reverse triiodothyronine (rT/sub 3/). These results suggest that both T/sub 3/ and rT/sub 3/ are deiodinated to T/sub 2/. Serum concentrations of T/sub 2/ in normal subjects decreased with age. Between 20 and 40 years the mean concentration was 4.3 +- 2.0 ng/dl (2 SD), between 41 and 60 years it varied from 1.9 to 5.8 ng/dl (3.8 +- 0.3 ng/dl, SE) and in elderly subjects have 60 years concentrations varied from unmeasurable to 4 ng/dl (2.9 +- 0.4 ng/dl, SE). Low serum T/sub 2/ concentrations were found in anorexia nervosa (2.5 +- 0.3 ng/dl, SE). In hypothyroidism the serum concentrations were low or unmeasurable. As most of the hypothyroid subjects were elderly their serum T/sub 2/ concentrations overlapped with the low values found in the elderly euthyroid subjects. In classical hyperthyroidism serum T/sub 2/ concentrations were greatly increased (3.3 to 31 ng/dl (11.8 +- 2.7 ng/dl, SE) but in ''T/sub 3/ toxicosis'' the concentrations were only modestly increased (2.4 to 8.8 ng/dl, 5.2 +- 0.8 ng/dl, SE).
- Research Organization:
- Univ. of Geneva
- OSTI ID:
- 5090531
- Journal Information:
- J. Clin. Endocrinol. Metab.; (United States), Vol. 45:3
- Country of Publication:
- United States
- Language:
- English
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550601* - Medicine- Unsealed Radionuclides in Diagnostics