Overexpression of Type 2 Iodothyronine Deiodinase in Follicular Carcinoma as a Cause of Low Circulating Free Thyroxine Levels
| Autor: | Brian W. Kim, Gilbert H. Daniels, P. R. Larsen, Anthony P. Weetman, Alkes L. Price, John W. Harney, B. J. Harrison |
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| Rok vydání: | 2003 |
| Předmět: |
Adult
Male endocrine system medicine.medical_specialty endocrine system diseases Endocrinology Diabetes and Metabolism Clinical Biochemistry Levothyroxine Iodide Peroxidase Biochemistry Thyroid function tests Thyroid carcinoma Endocrinology Thyroid peroxidase Internal medicine Adenocarcinoma Follicular medicine Humans Thyroid Neoplasms Thyroid Nodule Aged Triiodothyronine medicine.diagnostic_test biology business.industry Biochemistry (medical) Thyroid Thyroxine medicine.anatomical_structure Iodothyronine deiodinase biology.protein Thyroid function business medicine.drug |
| Zdroj: | The Journal of Clinical Endocrinology & Metabolism. 88:594-598 |
| ISSN: | 1945-7197 0021-972X |
| Popis: | Thyroid function is normally undisturbed in patients with thyroid carcinoma. We have identified three patients with large or widely metastatic follicular thyroid carcinoma who had a persistently increased ratio of serum T(3) to T(4) in the absence of autonomous production of T(3) by the tumor. To investigate the possibility of tumor-mediated T(4) to T(3) conversion, we assayed types 1 and 2 iodothyronine selenodeiodinase (D1 and D2) activity in a 965-g follicular thyroid carcinoma resected from one of these patients. The V(max) for D2 was 8-fold higher than in normal human thyroid tissue. Resection of this tumor, leaving the left thyroid lobe intact, normalized the serum T(3) to T(4) ratio. In two other patients, treatment with sufficient levothyroxine to suppress TSH was associated with a high normal T(3) and a subnormal free T(4) index. In one, concomitant administration of the D1 inhibitors, propylthiouracil and propranolol, did not decrease the elevated serum T(3) to T(4) ratio. These data illustrate that increased T(4) to T(3) conversion in follicular thyroid carcinomas, probably by D2, can cause a significant perturbation in peripheral thyroid hormone concentrations. |
| Databáze: | OpenAIRE |
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