Pituitary and peripheral tissues responses to the administration of L-T3 in resistance to thyroid hormone

Responses to the administration of incremental doses of L-T3 in 3 representative subjects: with RTH due to TR-beta gene mutation (left), RTH without a mutation in the TR genes (nonTR-RTH; right), and a normal individual (center). The hormone was given in 3 incremental doses, each for 3 days.
(A) Thyrotroph responses to TRH stimulation. Compared with normal, TSH responses are less suppressible by L-T3.
(B) Peripheral tissues responses. Note the stimulation of ferritin and SHBG and the suppression of cholesterol and CK in the normal subject. Responses in affected subjects, with or without a TR-beta gene mutation, were blunted or paradoxical.