THYROXINE BINDING GLOBULIN DEFICIENCY - CONSTITUTIONAL GROWTH RETARDATION ERRONEOUSLY DIAGNOSED AS ISOLATED THYROTROPIN DEFICIENCY

An 11-year-old boy with X-chromosome-linked thyroxine binding globulin (TBG) deficiency and constitutional growth retardation was erroneously treated for isolated thyroid stimulating hormone (TSH) deficiency and secondary hypothyroidism. Growth hormone, TSH, and adrenocorticotropic hormone were normal. Since TSH deficiency can be confused with TBG deficiency, it is recommended that all such patients be checked for TBG deficiency by comparison of the T-3 uptake with the protein bound iodine (PBI) concentration. The lack of response of a low PBI value to thyroid replacement may be another clue to TBG deficiency. © 1969 The C. V. Mosby Company.