Journal Article10.1089/THY.2004.14.1030
The Nature of Analogue-Based Free Thyroxine Estimates
26
TL;DR: Four analogue-based FT(4) assays passed tests of correlation with FT(2) concentrations, but they failed tests of specificity for FT(3) and accuracy in T(4), and protein-bound T( 4) binding protein contributed variably to test results.
read more
Abstract: Clinical laboratories often use analogue-based immunoassays to estimate serum free thyroxine (FT4) concentrations. These assays yield FT4 estimates that correlate closely with thyroxine (T4) binding protein concentrations. This correlation implies that either T4 binding proteins or protein bound T4 contribute to analogue-based FT4 values. To study the contributions made by T4 binding proteins to these FT4 estimates further, four analoguebased FT4 assays were applied to: (1) FT4 solutions without T4 binding proteins, (2) to T4 binding protein solutions without T4, and (3) to total T4 solutions containing T4 binding protein, FT4, and protein-bound T4. The FT4 estimates obtained with these solutions ranged from 0.2–8.6 ng/dL, when FT4 concentrations ranged from less than 0.2–12,000 ng/dL. In the FT4 solutions, gravimetrically determined FT4 concentrations were 500–12,000 ng/dL (0.5–12.0 µg/dL) without protein-bound T4, and the FT4 estimates obtained were 0.3–6.9 ng/dL. In the total T4 solutions, dialyzable F...
read more
Chat with Paper
AI Agents for this Paper
Find similar papers on Google Scholar, PubMed and Arxiv
Write a critical review of this paper
Analyze citations of this paper to find unaddressed research gaps
Citations
2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis
Douglas S. Ross,Henry B. Burch,David S. Cooper,M. Carol Greenlee,Peter Laurberg,Ana Luiza Maia,Scott A. Rivkees,Mary H. Samuels,Julie Ann Sosa,Marius N. Stan,Martin A. Walter +10 more
TL;DR: One hundred twenty-four evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice.
Hyperthyroidism and Other Causes of Thyrotoxicosis: Management Guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists
Rebecca S. Bahn,Henry B. Burch,David S. Cooper,Jeffrey R. Garber,M. Carol Greenlee,Irwin Klein,Peter Laurberg,I. Ross McDougall,Victor M. Montori,Scott A. Rivkees,Douglas S. Ross,Julie Ann Sosa,Marius N. Stan +12 more
TL;DR: Evidence-based clinical guidelines for the management of thyrotoxicosis are described that would be useful to generalist and subspeciality physicians and others providing care for patients with this condition.
1.2K
Hyperthyroidism and other causes of thyrotoxicosis: management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists.
Rebecca S. Bahn,Henry B. Burch,David S. Cooper,Jeffrey R. Garber,M. Carol Greenlee,Irwin Klein,Peter Laurberg,I. Ross McDougall,Victor M. Montori,Scott A. Rivkees,Douglas S. Ross,Julie Ann Sosa,Marius N. Stan +12 more
TL;DR: One hundred evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice as discussed by the authors.
1.1K
2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis.
Douglas S. Ross,Henry B. Burch,David S. Cooper,M. C. Greenlee,Peter Laurberg,Ana Luiza Maia,Scott A. Rivkees,Mary H. Samuels,Julie Ann Sosa,Marius N. Stan,Martin A. Walter +10 more
TL;DR: One hundred twenty-four evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice.
416
Hyperthyroidism and other causes of thyrotoxicosis: management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists.
R. Bahn,Henry B. Burch,David S. Cooper,Jeffrey R. Garber,M. C. Greenlee,Irwin Klein,P. Laurberg,I. McDougall,Victor M. Montori,Scott A. Rivkees,Douglas S. Ross,Julie Ann Sosa,Marius N. Stan +12 more
TL;DR: Evidence-based clinical guidelines for the management of thyrotoxicosis are described that would be useful to generalist and subspeciality physicians and others providing care for patients with this condition.
106
References
Limitations of a new free thyroxine assay (amerlex® free t4)
TL;DR: It appears that Amerlex® Free T4 is influenced by lower‐affinity, high‐capacity T4 binding sites in serum, so that apparent free T4 concentration may vary with changes in the concentration of such sites.
113
Effect of albumin concentration on the assay of serum free thyroxin by equilibrium radioimmunoassay with labeled thyroxin analog (Amerlex Free T4).
TL;DR: The data indicate that the albumin concentration influences FT4 values as measured by an RIA involving a thyroxin analog and that AmerlexFT4 values should be carefully interpreted when the patient has an abnormal concentration of serum albumin.
99
Validity of analog free thyroxin immunoassays.
TL;DR: The main implication of this analysis is that, to conform genuinely to the principles of "unbound analog" free hormone immunoassay, an analog must bind to serum proteins to a maximal extent of approximately 10% (but preferably less) in the absence of antibody.
91
Underestimates of serum free thyroxine (T4) concentrations by free T4 immunoassays.
TL;DR: A serum PBT4 dependent bias causes discordant FT4 measurements and probably explains the observed underestimates of FT4 in nonthyroidal illness.
77