THE NATURE OF THE SERUM IODINE AFTER LARGE DOSES OF I¹³¹*†

Elevated serum thyroglobulin. A marker of metastases in differentiated thyroid carcinomas.

“…The serum thyroglobulin levels in untreated patients with differentiated thyroid carcinoma ranged from 22.0 to 445.0 ng/ml with a mean of 144.3± 46.5 ng/ml (SEM) (n = 10). The mean serum thyroglobulin measured postoperatively in seven of these patients was 6.4±+1.5 ng/ml, not statistically different from the mean level of 5.1±0.49 ng/ml (range 0-20.7 ng/ml) observed in 71 out of 95 control subjects with detectable HTg levels. By contrast serum HTg levels were normal or undetectable in subjects with medullary carcinoma of the thyroid.…”

“…After the administration of 'I in patients with thyroid cancer, several authors have described the release of labeled iodinated proteins, among them thyroglobulin (6)(7)(8)(9). The.…”

The Thyroid Hormone-Plasma Protein Complex in Man. I. Differences in Different States of Thyroid Function12

“…It has been shown (8,9,15,16) that the administration of very large doses of I-131 results in the release into the circulation of an abnormal I-131-labelled product, probably thyroglobulin, which is proteinprecipitable but not butanol-soluble. Since it was therapeutically necessary to administer larger I-131 doses to our euthyroid subjects than to the patients with hyperthyroidism, the possibility had to be considered that the slower disappearance rate of the euthyroid plasma radioactivity in our studies was due to its content of an abnormally large, I-131-tagged thyroglobulin-like compound.…”

The Concentration and Significance of the Butanol-Extractable I131 of Serum in Patients with Diverse States of Thyroidal Function

“…Many investigators have, therefore, attempted to assess thyroidal function by measuring the concentration of protein-bound I'll (PB1181) in the plasma following the administration of radioactive iodine (7-11). The PBI111 (12), or even the total radioactivity in the plasma (13, 14), determined several days after the administration of the tracer, reflects the radioactivity of circulating thyroxine, except in patients who have received large doses of 1181 (15).It has been shown that the hormonal iodine which is extractable from serum with butanol and not re-extractable with alkali (hereafter referred to as the butanol-extractable iodine) is composed largely of thyroxine. Its concentration in serum differs significantly from that of the protein-bound iodine (16).…”

“…Many investigators have, therefore, attempted to assess thyroidal function by measuring the concentration of protein-bound I'll (PB1181) in the plasma following the administration of radioactive iodine (7)(8)(9)(10)(11). The PBI111 (12), or even the total radioactivity in the plasma (13,14), determined several days after the administration of the tracer, reflects the radioactivity of circulating thyroxine, except in patients who have received large doses of 1181 (15).…”