Abstract
In a case of hypothyroidism with clubbing of fingers and toes, exophthalmos, myxoedema tuberosum and myxoedema pretibiale, serum T4 value was low, but both values of serum T3 and TSH were normal and serum LATS was potitive. Three months later both values of serum T4 and T3 decreased and serum TSH value increased without any treatment. These results show that serum T3 as well as T4 might be related to the feedback control of TSH secretion. In a case of Pendred's syndrome, serum T4 value was low, values of serum T3 and BMR were within normal and serum TSH value was high. Normal serum T3 may have kept this patient in a state of compensatory hypothyroidism. In these patients, administration of 25-50 μg of l-T3 per day was sufficient to suppress the secretion of serum TSH from thyroid gland completely.
