Concentration of thyroxine-binding globulin: value of direct assay. Issue 6059 (19th February 1977)

• Record Type: Journal Article
• Authors: Burr, W A; Ramsden, D B; Evans, S E; Hogan, T; Hoffenberg, R
• Is Part Of: BMJ. Volume 1:Issue 6059(1977)
• Page Start: 485
• Page End: 488
• Publication Date: 1977-02-19
• Subjects: Medicine -- Periodicals; Medicine -- Periodicals; Medicine; Periodicals; 610
• DOI: 10.1136/bmj.1.6059.485
• Languages: English
• ISSNs: 0007-1447

Abstract

Abstract : The concentration of thyroxine-binding globulin (TBG) in the serum can now be measured by direct assays that are simple and inexpensive. Comparison of a direct measurement of TBG concentration with a widely used indirect method (Thyopac-3) showed that the indirect method was inaccurate when TBG concentrations were high. This will result in an increase in the derived free thyroxine index (FTI), so that euthyroid patients with a raised TBG concentration may be at risk of being labelled thyrotoxic. Correction of serum total thyroxine (T4) concentration according to the actual TBG concentration (T4:TBG ratio) provided a better correlation with thyroid state than FTI.