Nuclear thyroxine binding in human mononuclear blood cells from hyperthyroid and hypothyroid patients before and after treatment

Abstract

Nuclear binding of [¹²⁵I]T₄ in human mononuclear blood cells was examined in six hyperthyroid and six hypothyroid patients before and after treatment. In hypothyroid patients the nuclear T₄ binding was initially increased and subsequently normalized as the patients became euthyroid suggesting a homeostatic counter-regulation. The thyroid state did not affect the nuclear T₄ binding in hyperthyroid patients. Treatment with methimazol however increased the nuclear T₄ binding, suggesting either a direct effect of methimazol on the hormone-receptor interaction or that the patients had become slightly hypothyroid during the treatment. The TSH was shown not to affect nuclear T₄ binding. The thyroid state of the patients did not significantly affect the nuclear accumulation of the T₃ produced intracellularly by deiodination of T₄.

Key Words:

• myxoedema
• thyrotoxicosis
• T₄ receptors