Toxic multinodular goitre

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Toxic multinodular goiter
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Toxic multinodular goiter
Other namesToxic nodular goiter, Plummer's disease, multinodular toxic goiter, TMNG, MNTG
Most common causes of hyperthyroidism by age.[1]
SpecialtyEndocrinology

Toxic multinodular goiter (TMNG), also known as multinodular toxic goiter (MNTG), is an active

multinodular goiter associated with hyperthyroidism
.

It is a common cause of hyperthyroidism

Toxic multinodular goiter is the second most common cause of hyperthyroidism (after Graves' disease) in the developed world, whereas iodine deficiency is the most common cause of hypothyroidism in developing-world countries where the population is iodine-deficient. (Decreased iodine leads to decreased thyroid hormone.) However, iodine deficiency can cause goiter (thyroid enlargement); within a goitre, nodules can develop. Risk factors for toxic multinodular goiter include individuals over 60 years of age and being female.[5]

Signs and symptoms

Symptoms of toxic multinodular goitre are similar to that of hyperthyroidism, including:[5]

Causes

Sequence of events:[6]

  1. Iodine deficiency leading to decreased
    T4
    production.
  2. Induction of thyroid cell hyperplasia due to low levels of T4. This accounts for the multinodular goitre appearance.
  3. Increased replication predisposes to a risk of mutation in the TSH receptor.
  4. If the mutated TSH receptor is constitutively active, it would then become 'toxic' and produces excess T3/T4 leading to hyperthyroidism.

Diagnosis

Hyperthyroidism is diagnosed by evaluating symptoms and physical exam findings, and by conducting laboratory tests to confirm the presence of excess thyroid hormones. It is characterized by high levels of thyroid hormone in the blood along with a low level of thyroid-stimulating hormone (TSH). After diagnosing hyperthyroidism, a

radioactive iodine. This scan can identify toxic nodules, which appear as a single area of overactivity, as well as toxic multinodular goiter, which presents with multiple areas of overactivity. In addition, a thyroid ultrasound can be conducted to better evaluate the presence of thyroid nodules.[7]

Fine-needle aspiration for

Grave's disease
also shows hyperplasia, but typically more prominent thickening of follicular linings):

  • Diffuse thyroid hyperplasia typically shows variably sized follicles
    Diffuse thyroid hyperplasia typically shows variably sized follicles
  • Thyroid hyperplasia with a hyperplastic nodule. It characteristically has no capsule (distinguishing it from thyroid adenoma or carcinoma).
    Thyroid hyperplasia with a hyperplastic nodule. It characteristically has no capsule (distinguishing it from thyroid adenoma or carcinoma).
  • The follicular linings may be thickened, with papillary projections (but lack nuclear features of papillary thyroid carcinoma)
    The follicular linings may be thickened, with papillary projections (but lack nuclear features of
    papillary thyroid carcinoma
    )
  • The epithelium may also be flattened by enlarged follicles.
    The epithelium may also be flattened by enlarged follicles.
  • It can show hypercellular or microfollicular areas. There is no surrounding capsule (in contrast, a thyroid follicular adenoma or carcinoma is generally encapsulated).
    It can show hypercellular or microfollicular areas. There is no surrounding capsule (in contrast, a
    carcinoma
    is generally encapsulated).
  • As shown in these microfollicles, it can have mildly enlarged nuclei with mildly clumped chromatin, and clear cytoplasms, but cellular characteristics of papillary thyroid carcinoma are absent.
    As shown in these microfollicles, it can have mildly enlarged nuclei with mildly clumped chromatin, and clear cytoplasms, but cellular characteristics of papillary thyroid carcinoma are absent.
  • Thyroid hyperplasia with a Sanderson polster, which is a group of small follicles that protrude into the lumen of a larger follicle. It should not be confused for papillary projections.
    Thyroid hyperplasia with a Sanderson polster, which is a group of small follicles that protrude into the lumen of a larger follicle. It should not be confused for papillary projections.
  • Various forms of degeneration are typically seen, with various forms pictured.
    Various forms of degeneration are typically seen, with various forms pictured.

Treatments

Toxic multinodular goiter can be treated with antithyroid medications such as

methimazole, radioactive iodine, or with surgery.[5] Another treatment option is injection of ethanol into the nodules.[9]

A Cochrane review compared treatments using recombinant human thyrotropin-aided radioactive iodine to radioactive iodine alone.[10] In this review it was found that the recombinant human thyrotropin-aided radioactive iodine appeared to lead to a greater of thyroid volume at the increased risk of hypothyroidism.[10] No conclusive data on changes in quality of life with either treatments were found.[10]

History

The

medical eponyms "Plummer disease" (named after American physician Henry Stanley Plummer[12]) and "Parry disease" (named after English physician Caleb Hillier Parry) have been used to refer to toxic multinodular goiter, toxic adenoma, and toxic diffuse goiter (Graves' disease); the specific entity in each patient/case is not always clear retrospectively, especially in older literature. This is logical given that advanced medical imaging that can show what is happening at various places within a thyroid gland inside a living person (such as nuclear medicine imaging of radioiodine tracer uptake) was not available until after the 1940s.[citation needed
]

References

  1. .
  2. .
  3. .
  4. .
  5. ^ a b c A.D.A.M. Medical Encyclopedia (2012). "Toxic nodular goiter". U.S. National Library of Medicine. Retrieved 30 January 2013.
  6. ^ Toxic Nodular Goiter at eMedicine
  7. ^ "Toxic Nodule and Toxic Multinodular Goiter". American Thyroid Association. Retrieved 2023-02-15.
  8. ^ Philip R Orlander, MD, FACP; Chief Editor: George T Griffing, MD. "Toxic Nodular Goiter Workup". Medscape. {{cite web}}: |author= has generic name (help)CS1 maint: multiple names: authors list (link) Updated: Oct 25, 2021
  9. .
  10. ^ .
  11. ^ Elsevier, Dorland's Illustrated Medical Dictionary, Elsevier.
  12. Who Named It?

External links