Although there is abundant published evidence that radioiodinated antigens interfere in digoxin radioimmunoassays, other radioimmunoassays are similarly affected. We investigated the relationship of radioiodinated antigen structure to its function in the immunoassay. Carrier-free 125I-labeled iodotyrosine and iodohistamine derivatives were incubated with human serum, and the bound and free frac...

Filter paper discs saturated with dried blood can be used in the Immunotube solid-phase thyroxine radioimmunoassay. This assay utilizes polypropylene tubes to which antibody to thyroxine is covalently bound. The filter paper standards and samples are placed in the tubes, followed by an assay buffer that contains I125-labeled thyroxine and compounds to displace thyroxine from its binding protein...

Rising thyroid stimulating hormone (TSH) levels in patients being treated for primary hypothyroidism usually indicate poor compliance with thyroxine therapy. In rare instances, drugs or diseases affecting absorption of thyroxine or drugs that accelerate thyroxine metabolism can manifest in a similar fashion. Nephrotic syndrome is a rare cause of such a presentation though its presence can rapid...

A group of 13 normal subjects were evaluated for their extrathyroidal thyroxine distribution. The method employed the measurement of the acute plasma disappearance of a thyroxine-(131)I tracer and its concomitant uptake into the liver and forearm. The analysis of these parameters allowed the theoretical construction of a four compartmental mathematical model system comprised of the plasma, extr...

Few attempts have been made to relate the structure of substances deiodinated by the systems in vitro which degrade thyroxine to specific structural requirements necessary for the reaction. In general, it has been found that several thyronine derivatives may be degraded by the rabbit muscle or rat liver microsomal thyroxine-degrading systems, but that none is more efficiently degraded than thyr...

Dear Editor, About : “Çalık A, Küçüktülü U, Bilgin Y, Çinel A, Alhan E, Pişkin B. Prevention of recurrences after thyroidectomy in an endemic area with prophylactic levothyroxine use. Tr J Med Sci 29: 273-277, 1999." I have read an article entitled “Prevention of recurrences after thyroidectomy in an endemic area with prophylactic levothyroxine use” by Adnan Çalık and coworkers with a great int...

Various indexes of thyroid status were measured in sera from normal men and women, normal women who were using oral contraceptives, hyper. and hypothyroid patients, and hypothyroid patients being successfully managed with various forms of replacement therapy. Total circulating thyroxine concentrations were measured by three methods as well as the thyroxine.binding capacity of the serum inter-al...

After numerous negative experiments on the possible effect of thyroxine on oxidations in animal tissue slices and homogenates, experiments were tried with this hormone on a vegetable enzyme, ascorbic acid oxidase. It was found that small amounts of thyroxine stimulated the oxygen uptake of the ascorbic acid-ascorbic acid oxidase system. Since ascorbic acid oxidase is a copper protein (I), the e...

In previous reports (1, 2), it was suggested that the binding of thyroxine to human serum albumin resulted primarily from an electrostatic interaction between anionic portions of the thyroxine molecule and cationic sites on t.he protein. From the reduction in thyroxine binding exhibited by acetylated albumin preparations, it seemed likely that part of the reactive cationic sites were made up of...

Thyroid 2000;10:31–9. 6. Sapin R. Serum thyroxine binding capacity-dependent bias in five free thyroxine immunoassays: assessment with serum dilution experiments and impact on diagnostic performance. Clin Biochem 2001;34:367–71. 7. Christofides ND. Free analyte immunoassay. In Wild D, ed. The immunoassay handbook, 2nd ed. London: Nature Publishing Group, 2001:61–77. 8. Christofides ND, Wilkinso...