[The use of radioactive iodine in diagnosing thyroid diseases in Iceland. 1964].

A brief description of human iodine metabolism is given. The results of 4 hours, 24 hours and 48 hours thyroid I-131 uptake and 48 hours PBI-131 measurements in 88 (28 males, 60 females) euthyroid volunteers are presented (Table I, fig. 2 and 3). The uptake in Icelandic euthyroids is ca. 50% lower than in euthyroids in Great Britain and U.S.A. (Table II). A 4 hours uptake > 21% of dose is the best criterion for hyperthyrodism, but a 48 hours uptake < 5% the best criterion for hypothyroidism. 48 hr PBI-131 is of no aid in diagnosis of hypothyroidism, but of some value in the diagnosis of hyperthyroidism (> 0.2% dose/1 plasma).Clinical assessment of 96 patients (10 hypothyr. 49 euthyroid. 37 hyperthyr.) is compared with the assessment based on I-131 studies (tabl. III & IV, fig. 4,5 and 7). The results of TSH stimulation test on 1 clin. Euthyroid with low uptake and 7 hypothyroids (6 primary, 1 secondary) are presented (fig. 6). BMR results (normal = 15%) in 56 of these patients are compared with clinical assessment (table V). No correlation between I-131 uptake and BMR was found in euor hypothyroid, but some correlation was found in hyperthyroids (r = + 0.53).