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Evaluation of a new free-thyroxin assay

Journal Article · · Clin. Chem. (Winston-Salem, N.C.); (United States)
OSTI ID:5799360
The Amerlex Free Thyroxin (T/sub 4/) Radioimmunoassay Kit (Amersham International Ltd.) is a new direct equilibrium radioimmunoassay for free T/sub 4/ based on an antiserum with very high affinity for T/sub 4/, and a unique /sup 125/l-labeled T/sub 4/ analog as tracer. It is a very simple single-tube radioimmunoassay, making use of Amerlex particles to separate antibody-bound from free species. Interassay precision (CV) is 3.7% at 13 pmol/L and 2.3% at 30 pmol/L; within-assay precision is 4.2% at 21 pmol/L. The reference interval is 11-22 pmol/L. The assay did not misclassify any patients tested who had untreated myxedema or untreated thyrotoxicosis. The free T/sub 4/ assay excelled both the free T/sub 4/ index and the T/sub 4//T/sub 4/-binding globulin ratio in correcting for increased thyroxin-binding globulin from pregnancy, and it was better than the index but not better than the ratio in correcting for increased thyroxin-binding globulin in users of oral contraceptives.
Research Organization:
Queen Elizabeth Hospital, Woodville, South Australia
OSTI ID:
5799360
Journal Information:
Clin. Chem. (Winston-Salem, N.C.); (United States), Journal Name: Clin. Chem. (Winston-Salem, N.C.); (United States) Vol. 27:12; ISSN CLCHA
Country of Publication:
United States
Language:
English