[Can the thyrotropin (TSH) suppressive dose of L-thyroxine (T4) be individually predicted in athyroid patients?]

TSH-suppressive doses of L-thyroxine (T4) are needed in the treatment of athyreotic cancer patients in order to prevent metastases. We were interested to know whether the TSH-suppressive dose can be predicted on a body weight-or body surface basis in athyreotic individuals, which might save them the control TRH-test. 92 athyreotic patients (22 men, 70 females; age 25-81, mean 50.4 yrs; body weight ranging from 48-114 kg, mean 73), who have been operated for differentiated thyroid cancer and who have had at least one treatment ablative doses of 131-I, were investigated. After 4 weeks without thyroid hormone supplementation (checked by TSH serum concentration above 20 microU/ml) patients were set on 150 mcg of L-T4/day. TSH serum concentration before and 20' after 200 mcg of TRH were measured by the ultrasensitive TSH kit of Behringwerke. Total and free T4 as well as total T3 were also measured by radioimmunoassay kits. TRH tests were performed 6 weeks after start of treatment in 51 patients and 8 or more weeks respectively in 41 patients. Only the inclusion of the influence of age (multiple correlation) yielded a significant positive correlation between basal TSH and L-T4 dose/body weight.(ABSTRACT TRUNCATED AT 250 WORDS)