[Familial goitrous cretinism with giant goiter and hyperthyroglobulinemia: report of two siblings].

A 39 year-old-man and a 44 year-old-woman who was his elder sister were admitted to our hospital for study and treatment of goiter and hypothyroidism. Both had giant goiters. When he was about 3 years old goiter was first noticed since then the goiter slowly increased in size until the time of admission, while her goiter increased in size from when she was about 30 years old. Though both cases were already recognized as cretinism, they had not been treated. Perchlorate discharge test showed impaired iodide organification in both cases. Their serum thyroglobulin concentration was extremely high (1800 ng/ml). To our knowledge, there have been no case reports of goiterous cretinism due to impaired iodide organification with hyperthyroglobulinemia except the report by Hirota, Y. et al.