Variations in Thyroid Hormone Transport Proteins and Their Clinical Implications
- 1 January 1992
- journal article
- review article
- Published by Mary Ann Liebert Inc in Thyroid®
- Vol. 2 (3), 237-245
- https://doi.org/10.1089/thy.1992.2.237
Abstract
Variations in major thyroid hormone transport proteins may be inherited or acquired and may be associated with changes in serum concentration of the proteins or their affinity for thyroid hormones. These variations most frequently involve thyroxine-binding globulin (TBG), but changes in transthyretin and albumin are also observed. The consequent alteration of thyroid hormone-binding capacity in serum is associated with variations in total thyroid hormone concentration. Increased serum total thyroid hormone levels are found in subjects with TBG excess, familial dysalbuminemic hyperthyroxinemia, and transthyretin-associated hyperthyroxinemia. Conversely, diminished serum thyroid hormone values are observed in subjects with TBG deficiency, and decreased concentration or affinity of transthyretin and albumin is not associated with variations in serum concentrations of thyroid hormones. The transport protein-associated variations in serum total thyroid hormone concentrations do not reflect a change in thyroid status. Euthyroidism can be easily established in subjects with transport protein abnormalities by the normal free thyroid hormone and TSH concentrations. It is, however, crucial to select methods for free thyroid hormone measurement that are not affected by abnormalities of transport proteins. Some assays, such as the analog method, often provide artifactual and misleading results, which may lead to inappropriate and even detrimental treatments. The evolutionary advantage of TBG (and albumin) in terms of thyroid homeostasis still remains to be elucidated.Keywords
This publication has 50 references indexed in Scilit:
- Molecular basis of inherited thyroxine-binding globulin defectsTrends in Endocrinology & Metabolism, 1992
- Molecular cloning and primary structure of rat thyroxine-binding globulinBiochemistry, 1991
- Alterations in prealbumin concentration after adrenal autotransplantation for Parkinson's diseaseExperimental Neurology, 1990
- Familial Occurrence of Dysalbuminaemic Hyperthyroxinaemia, Lipomatosis and Ankylosing SpondylitisScandinavian Journal of Rheumatology, 1990
- The plasma membrane and thyroid hormone entry into cellsTrends in Endocrinology & Metabolism, 1989
- Sequence of the variant thyroxine-binding globulin of Australian aborigines. Only one of two amino acid replacements is responsible for its altered properties.JCI Insight, 1989
- Maternal Free Thyroxine and Thyroxine-Binding Globulin during Pregnancy Ending in Congenital Malformations in the OffspringGynecologic and Obstetric Investigation, 1989
- Protein binding and stability of norepinephrine in human blood plasma.-Involvement of prealbumin, ∝1-acid glycoprotein and albuminLife Sciences, 1988
- Iatrogenic hypothyroidism and postpartum hyperthyroidism in familial dysalbuminaemic hyperthyroxinaemia.BMJ, 1987
- A PREALBUMIN VARIANT WITH AN INCREASED AFFINITY FOR T4 AND REVERSE‐T3Clinical Endocrinology, 1984