Toxic multinodular goitre

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

• heat intolerance
• muscle weakness/wasting
• hyperactivity
• fatigue
• tremor
• irritability
• weight loss
• osteoporosis
• increased appetite
• non-painful goitre (swelling of the thyroid gland)
• tachycardia (high heart rate - above 100 beats per minute at rest in adults)
• tracheal compression
• exophthalmos

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.

Toxic multinodular goiter can be treated with antithyroid medications such as propylthiouracil or methimazole, radioactive iodine, or with surgery.[5] Another treatment option is injection of ethanol into the nodules.[7]

The usage of terminology for types of goiter has varied over the past century. Physicians and surgeons tend to differentiate among solitary-nodule goiter, multinodular goiter, and non-nodular goiter more thoroughly in recent decades than they formerly did. Thus some sources have described, or still describe, thyroid adenoma (toxic adenoma) as synonymous with toxic multinodular goiter,[8] but other sources differentiate those two as single-nodule disease versus multinodular disease (respectively) with pathogenesis that is likely differing in most cases (e.g., single neoplastic cell clone versus multifocal or diffuse molecular metabolic change). The medical eponyms "Plummer disease" (named after American physician Henry Stanley Plummer[9]) 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.