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The Plummer effect is one of several physiological feedforward mechanisms taking place in follicular cells of the healthy
The Plummer effect is one of several physiological feedforward mechanisms taking place in follicular cells of the healthy thyroid gland
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobe (anatomy), lobes. The lower two thirds of the lobes are connected by a thin band of Connective tissue, tissue cal ...
and preventing the development of thyrotoxicosis
Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. ...
in situations of extremely high supply with iodine
Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...
.
History
In 1923 the American physicianHenry Stanley Plummer
Henry Stanley Plummer ( – ) was an American internist and endocrinologist who, along with William Mayo, Charles Mayo, Augustus Stinchfield, E. Starr Judd, Christopher Graham, and Donald Balfour founded Mayo Clinic. Plummer is also immortali ...
discovered that high-dose iodine may be effective in the treatment of Graves’ disease
Graves' disease (german: Morbus Basedow), also known as toxic diffuse goiter, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyro ...
. Today, “Plummering”, i.e. therapy with Lugol's iodine solution, is one of several emergency measures in the management of severe thyrotoxicosis.
Mechanism
Via the Plummer effect, a high iodine concentration inhibits the proteolysis of thyroglobulin and the release of pre-formedthyroid hormones
File:Thyroid_system.svg, upright=1.5, The thyroid system of the thyroid hormones T3 and T4
rect 376 268 820 433 Thyroid-stimulating hormone
rect 411 200 849 266 Thyrotropin-releasing hormone
rect 297 168 502 200 Hypothalamus
rect 66 216 386 25 ...
from thyroid follicles. Therefore, its mechanism differs from that of the Wolff–Chaikoff effect
The Wolff–Chaikoff effect is a presumed reduction in thyroid hormone levels caused by ingestion of a large amount of iodine.
It was discovered by Drs. Jan Wolff and Israel Lyon Chaikoff at the University of California, Berkeley: in 1948, th ...
, where iodine inhibits the uptake of iodine in thyroid cells and the formation of thyroid hormones, and of the dehalogenase inhibition effect, where high iodine levels block deiodinase
Deiodinase (or "Monodeiodinase") is a peroxidase enzyme that is involved in the activation or deactivation of thyroid hormones.
Types
Types of deiodinases include:
Iodothyronine deiodinases catalyze release of iodine directly from the thyron ...
s and other dehalogenase A dehalogenase is a type of enzyme that catalyzes the removal of a halogen atom from a substrate.
Examples include:
*Reductive dehalogenases
*4-chlorobenzoate dehalogenase
* 4-chlorobenzoyl-CoA dehalogenase
* Dichloromethane dehalogenase
* Fluoroa ...
s.
The Plummer effect lasts about 7 to 10 days, but unlike the Wolff-Chaikoff effect, it isn't subject to an escape phenomenon.
The three different mechanisms of high iodine response, the Plummer effect, the Wolff-Chaikoff inhibition effect, and the adaptive escape phenomenon, synergistically work together to fend off potentially harmful consequences of excess iodine load and ensure thyroid homeostasis.
Clinical implications
Unlike the Wolff–Chaikoff effect, the Plummer effect does not prevent the thyroid from taking up radioactive iodine, e.g. in the case of nuclear emergencies. Therefore, "plummering" with high-dose iodine is only effective in a short time window after the release of radionuclides. Wrong timing of iodine use may even increase the risk by triggering the Plummer effect. The Plummer effect is, however, helpful in the management of thyrotoxicosis, where the usage of Lugol’s solution helps to limit the release of thyroid hormones into the bloodstream.See also
*Jod-Basedow phenomenon
The Jod-Basedow effect (also Jod-Basedow syndrome and Jod-Basedow phenomenon) is hyperthyroidism following administration of iodine or iodide, either as a dietary supplement, iodinated contrast medical imaging, or as a medication (mainly Amiodaron ...
*Potassium iodide
Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are us ...
*Lugol's iodine
Lugol's iodine, also known as aqueous iodine and strong iodine solution, is a solution of potassium iodide with iodine in water. It is a medication and disinfectant used for a number of purposes. Taken by mouth it is used to treat thyrotoxicosi ...
*Wolff–Chaikoff effect
The Wolff–Chaikoff effect is a presumed reduction in thyroid hormone levels caused by ingestion of a large amount of iodine.
It was discovered by Drs. Jan Wolff and Israel Lyon Chaikoff at the University of California, Berkeley: in 1948, th ...
References