Serum thyrotropin response to thyrotropin-releasing hormone and free thyroid hormone indices in patients with familiar thyroxine-binding globulin deficiency.
The response in serum thyrotropin (TSH) to synthetic thyrotropin-releasing hormone (TRH) as well as serum free thyroxine index (FT4I) and free triiodothyronine index (FT3I) was investigated in six patients with familial thyroxine-binding-globulin (TBG) deficiency. The total serum thyroxine (T4) and triiodothyronine (T3) concentrations were significantly decreased, compared with those of normal subjects (3,4 +/- 0.9 microng/dl, mean +/- S.D. vs. 9.0 +/- 1.5 microng/dl, p less than 0.01 and 87 +/- ng/dl vs. 153 +/- 37 ng/dl, p less than 0.01, respectively). FT4I was lower than the normal range in all but one (5.3 +/- 1.5 vs. 8.9 +/- 1.6, p less than 0.01), whereas FT3I was all in the normal range and of no significant difference from the normal control (132 +/- 22 vs 148 +/- 25). Serum TSH concentrations in TBG deficiency were all in the normal range (1.0-4.2 micronM/ml) and the maximum TSH increments following TRH 500 microng iv were 8.9 +/- 2.0 micronU/ml and of no significant difference from the normal control (10.2 +/- 4.5 micronU/ml). These results indicate that the euthyroid state in familial TBG deficiency is more clearly defined by TRH-test and the normal response to TRH in familial TBG deficiency is presumably under the control of the serum free T3 level rather than the serum free T4 level.
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008661:Metabolism, Inborn Errors / Q000097:blood / Q000235:genetics* / Q000503:physiopathology; D008875:Middle Aged; D012712:Serum Globulins / Q000172:deficiency*; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000503:physiopathology; D013972:Thyrotropin / Q000097:blood*; D013973:Thyrotropin-Releasing Hormone; D013974:Thyroxine / Q000097:blood*; D013975:Thyroxine-Binding Proteins / Q000172:deficiency*; D014284:Triiodothyronine / Q000097:blood*
D012712:Serum Globulins; D013975:Thyroxine-Binding Proteins; D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D013972:Thyrotropin; D013974:Thyroxine