Since our letter was printed in January 1989, we have come across an additional example of thyroxine-binding globulin (TBG) excess associated with hypothyroidism.
In a recent article, Menon reported the case of a 21-month-old boy with developmental and growth delay and other clinical features of hypothyroidism. Investigations confirmed the diagnosis of hypothyroidism: serum thyroxine (T4) 28 nmol/L (normal range 60 to 140 nmol/L), thyroid-stimulating hormone (TSH) 100 mU/L (normal range 2 to 10 mU/L), and bone age 4 months.
