Toxic nodular goiter
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|Toxic nodular goiter|
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Toxic nodular goiter (TNG) (or Plummer syndrome) is a condition that can occur when a hyper-functioning nodule develops within a longstanding goiter. This results in hyperthyroidism, without the ophthalmologic effects of increased levels of thyroid hormone as in Grave's disease. These toxic multi or uni-nodular goiters are most common in women over the age of 60.
Toxic nodular goiter is the presence of thyrotoxicosis and thyroid nodules. It is prevalent in people older than 40 years old who have an iodine deficiency. There is a much higher incidence of TNG in European countries in comparison to the United States. This condition is not common in the United States and Canada due to the iodine addition in table salt. Americans consume much higher dosages of iodine compared to the 25–100 ug/day that Europeans consume.
TNG is caused by a toxic multinodular goiter. Autonomous thyroid nodules become hyper-functional from mutations in the follicular cell. The mutation activates cAMP (cyclic adenosine monophosphate), causing an increase in the cells' function and growth. This is different from the thyroid condition called Grave’s disease, as Grave’s disease causes a hyper-function from external factors such as immunoglobulin that activate the TSH receptors. Hyper-function of TSH, thyroid stimulating hormone, activates the thyroid, which in excess can cause a condition known as goiter. The nodules that form could be driven by a loss of inhibition or gain of function mutations; however, this is purely speculation as the cause is still unknown. These nodules are assumed to be irreversible and when functional can lead to thyrotoxicosis.
Thyrotoxicosis has been documented to have some cases of spontaneous remission without treatment as seen in the study done by Siegel and Lee. It is possible that the remission of thyrotoxicosis is a result of spontaneous hemorrhage and cystic degeneration. This situation means that bleeding would occur in the thyroid, which could cause the nodules to break down, reversing the symptoms. These results of spontaneous remission were contrary to the study’s previous results showing that the nodules were irreversible. Patients presenting symptoms of toxic nodular goiter can also be treated using the same procedures as hyperthyroidism.
- Stedman's Electronic Medical Dictionary
- synd/1094 at Who Named It?
- H. S. Plummer. The clinical and pathological relationship of simple and exophthalmic goiter. American Journal of the Medical Sciences, Thorofare, N.J., 1913, 146: 790-795. Transactions of the Association of American Physicians, Philadelphia, 1928, 43: 159.
- Siegel, R.D., and Lee, S.L. Toxic nodular goiter: Toxic adenoma and toxic multinodular goiter. (1998). Endocrinology & metabolism clinics of North America, 27:1. P.151-168