Toxic multinodular goitre

Toxic multinodular goitre (also known as toxic nodular goitre, toxic nodular struma) is a form of hyperthyroidism - where there is excess production of thyroid hormones. It is characterized by functionally autonomous nodules. It emerges insidiously from nontoxic multinodular goitre.

It is the second most common cause of hyperthyroidism (after Graves' disease) in the developed world. In countries where the population is iodine-deficient i.e. the developing world, iodine deficiency is the most common cause of hypothyroidism. (Decreased iodine leads to decreased thyroid hormone.) However, iodine deficiency can cause goitre (thyroid enlargement); within a goitre, nodules can develop.

Symptoms

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

• heat intolerance
• muscle weakness/wasting
• hyperkinesis
• tremor
• irritability
• weight loss
• osteoporosis
• increased appetite
• goitre (swelling of the thyroid gland)
• tachycardia (high heart rate - above 100 bpm at rest in adults)

Causes

Sequence of events ^[1]

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 hyperthryoidism.

Related eponym

Plummer's disease is named after the American physician Henry Stanley Plummer but refers to a single toxic nodule (adenoma) which may present with the background of a suppressed multinodular goitre.^[2]

Footnotes

1. ^ http://emedicine.medscape.com/article/120497-overview
2. ^ Plummer's disease eponymously named after Henry Stanley Plummer at Who Named It?

External links

• Photo of patient
• Photo of goitre