active principle of the thyroid gland, 1915, from thyro-, comb. form of thyroid, + oxy- (apparently a reference to the oxygen atom present in it, but OED has it as a shortening of oxy-indol) + chemical suffix -ine (2), denoting an amino acid.
1. After 65 days , serum thiiodothronine ( T 3 ), thyroxine ( T 4 ) and thyroid - stimulating ( TSH ) were analyzed by enzyme exaggeration radioimmunoassays.