3,5,3′-Triiodothyronine Thyrotoxicosis due to Increased Conversion of Administered Levothyroxine in Patients with Massive Metastatic Follicular Thyroid Carcinoma
| Autor: | Emiko Nomura, Fumio Matsuzuka, Kaoru Kobayashi, Nobuyuki Amino, Nagaoki Toyoda, Yuuki Takamura, Akihiro Miya, Yasuhiro Ito, Mitsushige Nishikawa, Akira Miyauchi |
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| Rok vydání: | 2008 |
| Předmět: |
Adult
Male medicine.medical_specialty Endocrinology Diabetes and Metabolism Clinical Biochemistry Levothyroxine Thyroid Function Tests Iodide Peroxidase Biochemistry Thyroid function tests Thyroid carcinoma Endocrinology Internal medicine Adenocarcinoma Follicular Follicular phase Prevalence medicine Humans Thyroid Neoplasms Neoplasm Metastasis Thyroid cancer Aged Aged 80 and over Triiodothyronine medicine.diagnostic_test business.industry Biochemistry (medical) Middle Aged medicine.disease Tumor Burden Thyroxine Thyrotoxicosis Iodothyronine deiodinase Disease Progression Adenocarcinoma Female business medicine.drug |
| Zdroj: | The Journal of Clinical Endocrinology & Metabolism. 93:2239-2242 |
| ISSN: | 1945-7197 0021-972X |
| DOI: | 10.1210/jc.2007-2282 |
| Popis: | Some patients with massive metastatic thyroid carcinoma exhibit T(3) thyrotoxicosis. We investigated the prevalence and cause of T(3) thyrotoxicosis and the clues to the diagnosis.Serum free T(3) (FT(3)), free T(4) (FT(4)), and TSH were measured in patients with massive metastases from papillary, follicular, or medullary thyroid carcinomas (31, 20, and seven patients, respectively). Patients without recurrence served as controls. Thyrotoxic patients were reexamined 1 wk after withdrawal of levothyroxine. Type 1 and type 2 iodothyronine deiodinase (D1 and D2) activities were measured in three tumor tissues from thyrotoxic patients.The serum FT(3) level and FT(3)/FT(4) ratio in the follicular carcinoma (FC) group were significantly higher than those in the papillary carcinoma group or patients without recurrence. Four patients (20%) in the FC group but none in the other groups demonstrated T(3) thyrotoxicosis or a FT(3)/FT(4) ratio greater than 3.5. One week after withdrawal of levothyroxine, both FT(3) and FT(4) levels decreased. Retrospective measurements of FT(3) in frozen stored sera demonstrated that FT(3) exceeded the upper normal limit when FT(4) began to decrease but remained within the normal range. Tumor tissues showed high D1 and D2 activities.Twenty percent of patients with massive metastatic FC exhibited T(3) thyrotoxicosis, most likely due to increased conversion of T(4) to T(3) by tumor expressing high D1 and D2 activities. Occasional measurement of serum FT(3) in addition to FT(4) and TSH is recommended in patients with massive metastatic FC, especially when serum FT(4) decreases on fixed doses of levothyroxine. |
| Databáze: | OpenAIRE |
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