What happens during the Organification of iodide?
Organification is a biochemical process that takes place in thyroid gland. It is the incorporation of iodine into thyroglobulin for the production of thyroid hormone, a step done after the oxidation of iodide by the enzyme thyroid peroxidase (TPO).
How does iodide inhibit thyroid hormone release?
Iodide Salt☆ In normal individuals, excess iodide inhibits thyroid hormone synthesis. This is referred to as the acute Wolff-Chaikoff effect. The proposed mechanism is that iodopeptide(s) are formed that temporarily inhibit thyroid peroxidase (TPO) mRNA and protein synthesis and, therefore, thyroglobulin iodinations.
How does iodine affect hyperthyroidism?
Too much iodine can make hyperthyroidism worse by leading the thyroid gland to produce too much thyroid hormone. A person with hyperthyroidism should avoid eating excessive amounts of iodine-rich foods, such as: iodized salt.
Why does iodine cause hypothyroidism?
Its symptoms are very similar to those of hypothyroidism, or low thyroid hormones. Since iodine is used to make thyroid hormones, an iodine deficiency means your body can’t make enough of them, leading to hypothyroidism.
What is the mechanism of action of thyroid hormones?
Thyroid hormone receptors function by binding to specific thyroid hormone-responsive sequences in promoters of target genes and by regulating transcription. Thyroid hormone receptors often form heterodimers with retinoid X receptors.
What is the role of thyroglobulin in thyroid hormone synthesis?
Thyroglobulin (Tg) acts as a substrate for the synthesis of the thyroid hormones thyroxine (T4) and triiodothyronine (T3), as well as the storage of the inactive forms of thyroid hormone and iodine within the follicular lumen of a thyroid follicle.
What is the role of iodine in thyroid hormone synthesis?
Iodine plays a key role in the regulation of thyroid function and thyrocyte proliferation, and this phenomenon is called “autoregulation.” Excess iodine causes reduced hormone secretion, thyroglobulin proteolysis, and thyroid blood flow, and it also inhibits thyroid follicular cell growth in vivo and thyrocyte …
What affects iodine absorption?
Consumption of foods that contain goitrogens, substances that interfere with the uptake of iodine in the thyroid, can exacerbate iodine deficiency [2]. Foods high in goitrogens include soy, cassava, and cruciferous vegetables (e.g., cabbage, broccoli, and cauliflower).
Does high iodine intake cause hyperthyroidism?
Excess iodine intake is considered to be associated with hyperthyroidism or hypothyroidism in some vulnerable individuals [5, 6]. Iodine-induced hyperthyroidism (IIH) has been reported as a side effect of iodine supplementation. This is also called as “Jod-Basedow phenomenon”.
What is the target of the thyroid hormone?
| Endocrine gland/ source of hormone | Hormone | Target organ or tissue |
|---|---|---|
| Anterior pituitary (adenohypophysis) | LH (luteinizing hormone) | Ovaries / testes (Leydig cells) |
| GH (growth hormone) | All tissues | |
| TSH (thyroid stimulating hormone) | Thyroid gland | |
| Prolactin | Mammary gland |
What is the pathophysiology of organification defect in iodine?
Organification defect in iodine caused by abnormal H 2 O 2 production is rare, so abnormal Tg and TPO synthesis is thought to be the major cause of defective organification of iodine. The prevalence of neonatal hypothyroidism is approximately 1/4000, one-fifth of which is caused by genetically determined thyroid dyshormonogenesis.
What is the mechanism of action of iodine in the thyroid?
Iodide is known to control thyroid function. Its main effects are to decrease the response of the thyroid to thyrotropin (TSH); to acutely inhibit its own oxidation; to reduce its trapping after a delay; and, at high concentrations, to inhibit thyroid hormone secretion12).
Does iodine deficiency affect thyroid function long term?
Recent studies demonstrated that long-term thyroid function of subjects who experienced both iodine deficiency and iodine excess during childhood tended to be abnormal despite optimization of their current iodine intake.
What is the historical method to evaluate iodine nutrition?
Assessment of the size of the thyroid is the historical method to evaluate iodine nutrition because iodine deficiency is associated with an increased goiter rate19). In areas of moderate to severe iodine deficiency, iodine status had been assessed by goiter palpation.
