Elevation of Sex Hormone Binding Globulin (SHBG) Levels in Some Sera with Inherited Increase in Thyroxine Binding Globulin (TBG)
Previous observations reported from this laboratory have shown that there is often an elevation of sex hormone-binding globulin (SHBG) in sera with excess thyroxine (T4) protein binding (e.g., familial dysalbuminemic hyperthyroxinemia (FDH) (1). The elevation of sex hormone transport protein was apparently not an estrogen-mediated effect, as cortisol-binding globulin (CBG) levels in sera with elevated SHBG were normal. Since SHBG is a thyroid hormone (TH) sensitive protein, the possibility was entertained that the elevation of SHBG in subjects with excess T4 protein binding (as in FDH) may have been due to the availability of a greater than normal amount of T4 for tissue uptake (despite a normal level of free thyroxine (FT4)). In view of these observations, SHBG determinations, as well as in vitro T4 uptakes from sera, were studied in another hyperthyroxinemic syndrome caused by an excess of T4 transport protein, viz. inherited TBG increase.
KeywordsThyroxine Binding Globulin Familial Dysalbuminemic Hyperthyroxinemia Thyroxine Binding Globulin Concentration Excess Thyroxine
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- 1.Premachandra BN, Nisula B, Pardridge WM, et al. 59th Meeting Amer Thyroid Assn, New Orleans, LA, 1983, p T-25.Google Scholar