[Hormone replacement in patients with carcinoma of the thyroid (author's transl)]

82 patients with well-differentiated thyroid carcinoma had been treated by total thyroidectomy and radioiodine destruction of any residual thyroid tissue. They were then given high doses of L-thyroxine (T4), enough to suppress endogenous stimulation by TSH, the recommended dose being at least 300 microgram daily. Six weeks after starting 150 microgram T4 daily there was no significant response to 400 microgram TRH i.v. in 56% of the 82 patients. The T4 dose was then increased until all TRH tests had become negative. There was a significant correlation between the number of negative tests and body surface: at a dose of 40-60 microgram/m2 none of the tests was negative, while at a dose of 80-100 microgram/m2 the test was negative in 83%, the frequency of negative tests increasing up to 94% at higher doses. Mild hyperthyroidism occurred in 17%. It is concluded that after adequate surgical and radioiodine treatment 80-100 microgram/m2 T4 should be given to patients with well-differentiated thyroid carcinoma. The effectiveness of suppressing TSH levels should be checked with the TRH test after six weeks.