Familial thyroxin-binding globulin excess with ichthyosis: a case report.

Thyroxin (T4) binding globulin (TBG) the major thyroid hormone transport protein in humans. Congenital or acquired problems lead to TBG excess. Inheritance of TBG excess follows an X-linked pattern. A 21-month-old boy with ichthyosis was referred to the Pediatric Endocrinology Clinic with high levels of thyroid hormones (TT3 = 325 ng/dl, TT4 23 microg/dl, FT3 = 3.49 pg/dl, FT4 = 1.44 ng/dl, TSH = 2.48 microIU/ml). He was clinically euthyroidic. Thyroid gland was normal in size and homogeneous. Thyroid autoantibodies were negative. TSH responded normally to thyroid releasing hormone (TRH) stimulus. TBG was elevated (56 microg/ml). Family investigation revealed high levels of TBG in mother grandfather, and an uncle. To our knowledge, no other TBG excess with ichthyosis has been reported in the literature.