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Anatomy and Physiology of Head and Neck Endocrine Glands
Published in R James A England, Eamon Shamil, Rajeev Mathew, Manohar Bance, Pavol Surda, Jemy Jose, Omar Hilmi, Adam J Donne, Scott-Brown's Essential Otorhinolaryngology, 2022
Synthesis and release of thyroid hormones begin with absorption of iodine from the small intestine. Thyroid cells actively concentrate iodine at a level 20–50 times higher than plasma levels. Within the follicular cells, iodine is oxidised and bound to thyroglobulin. Thyroglobulin forms the polypeptide framework from which T3 and T4 are synthesised. Production of thyroglobulin is unique to the thyroid; it can therefore serve as a tumour marker following total thyroidectomy and radioiodine treatment for thyroid cancer.
Thyroid cancer
Published in Anju Sahdev, Sarah J. Vinnicombe, Husband & Reznek's Imaging in Oncology, 2020
Gitta Madani, Polly S Richards
Total thyroidectomy is still undertaken for most papillary carcinomas (and their variants) and follicular and Hürthle cell carcinomas that are larger than 1 cm, but there is a trend towards partial thyroidectomy for low grade and borderline tumours. Lymph node dissection is undertaken if there is nodal involvement. Postoperative radioactive iodine therapy is usually given, and the patient rescanned with 123I at 3–6 months to confirm complete ablation and the absence of metastatic disease. Thyroid hormone is administered (often after radioiodine treatment is completed) to replace hormone and inhibit TSH production. Thyroglobulin as a tumour marker is used in the follow-up of patients after surgery but is only accurate as a marker when there is complete absence of thyroid tissue (13).
Endocrine tumours
Published in Peter Hoskin, Peter Ostler, Clinical Oncology, 2020
Patients treated for differentiated thyroid cancer require life-long follow-up. This will involve regular thyroglobulin measurements. In the early post-treatment period whole body iodine uptake scans are performed. Thyroid hormone replacement therapy is usually withdrawn 2–6 weeks before such investigations. This precipitates a physiological rise in TSH, and therefore acts as a provocation test to facilitate detection of occult disease. In recent years, recombinant thyrotropin-α (Thyrogen®) given by intramuscular injection has been used for those individuals who do not have an adequate TSH response to hormone withdrawal, and for those where the transient myxoedema after hormone withdrawal is intolerable. A thyroglobulin level of >2 ng/mL 72 hours after TSH provocation usually warrants further investigation (neck ultrasound or MRI, CT scan of the thorax, whole body radioiodine scan) to exclude local relapse and distant metastatic disease.
Thyroid-dedicated internally-cooled wet electrode for benign thyroid nodules: experimental and clinical study
Published in International Journal of Hyperthermia, 2022
So Yeong Jeong, Jung Hwan Baek, Sae Rom Chung, Young Jun Choi, Ki-Wook Chung, Tae Yong Kim, Jeong Hyun Lee
The laboratory findings in the clinical study were as follows. The CBC and blood coagulation tests of all patients were normal at pretreatment evaluation. The initial mean TSH, fT4 and T3 were 2.1 ± 1.8 μU/ml (0.08–8.2), 1.3 ± 0.3 ng/dl (1.0–2.5) and 149.7 ± 23.0 ng/dl (116–202), respectively. The initial calcitonin and thyroglobulin were 2.1 ± 1.2 pg/ml (1.5–5.2) and 36.6 ± 52.1 ng/ml (1.5–233), respectively. In the initial laboratory test, eight patients had an elevated thyroglobulin level with a mean of 74.8 ± 67.4 ng/ml (range: 32.5–233). After RFA, thyroid function was well preserved in all patients, and the mean thyroglobulin level had significantly decreased to 26.9 ± 62.2 ng/ml at the 6-month follow-up (p=.046). Five out of the eight patients who had an initial elevated thyroglobulin level were normal on a 6-month follow-up after RFA.
2022 Expert consensus on the use of laser ablation for papillary thyroid microcarcinoma
Published in International Journal of Hyperthermia, 2022
Lu Zhang, Wei Zhou, Jian Qiao Zhou, Qian Shi, Teresa Rago, Giovanni Gambelunghe, Da Zhong Zou, Jun Gu, Man Lu, Fen Chen, Jie Ren, Wen Cheng, Ping Zhou, Stefano Spiezia, Enrico Papini, Wei Wei Zhan
Expert Recommendation 19: In the event of local hemorrhage, local pressure should be applied until the bleeding stops. Surgical consultation is needed in case of severe bleeding. Recommendation strength: strong recommendation; low quality evidence.3. Abnormal thyroid function is a minor complication after PLA. A transient increase of serum anti-thyroid antibodies and thyroglobulin levels may be observed. Delayed transient hyperthyroidism or hypothyroidism is rare and generally self-limiting [28]. If hyperthyroidism occurs, the majority of patients will spontaneously recover by avoiding iodine in their diet. Severe hyperthyroidism is treated using oral antithyroid drugs. If thyroid hormone surge occurs, levothyroxine tablets can be taken orally. Thyroid function should be monitored regularly in these patients, with dosage adjusted accordingly.
Thyroid-disrupting effects of chlorpyrifos in female Wistar rats
Published in Drug and Chemical Toxicology, 2022
Joice Karina Otênio, Karine Delgado Souza, Odair Alberton, Luiz Rômulo Alberton, Karyne Garcia Tafarelo Moreno, Arquimedes Gasparotto Junior, Rhanany Alan Calloi Palozi, Emerson Luiz Botelho Lourenço, Ezilda Jacomassi
Thyroid hormones are produced in a process that involves the active transport of iodine into follicles through the specific transmembrane transporter sodium/iodide symporter, followed by the oxidation and incorporation of tyrosine residues in the thyroglobulin molecule. This iodination of tyrosine results in monoiodinated (MIT) and diiodinated (DIT) residues that are enzymatically bound to form T3 and T4 (Köhrle et al.2018). Iodinated thyroglobulin that contains MIT, DIT, T3, and T4 is stored as an extracellular polypeptide in colloids near the lumen of thyroid follicular cells. Hormone release occurs through endocytosis and the lysosomal digestion of thyroglobulin in follicular cells. Although the thyroid gland preferentially produces T4, the main circulating thyroid hormone is T3 (Yavuz et al.2019). More than 99% of T3 and T4 combine immediately with various plasma proteins, including thyroxine-binding globulin, thyroxine-binding prealbumin, and albumin. Thus, T3 and T4 levels can be measured as a total (free + bound protein) or as a free fraction (Mullur et al.2014).