Toxic multinodular goitre
|Toxic multinodular goiter|
|Classification and external resources|
It is a common cause of hyperthyroidism in which there is excess production of thyroid hormones from functionally autonomous thyroid nodules, which do not require stimulation from thyroid stimulating hormone (TSH).
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. Risk factors for toxic multinodular goiter include individuals over 60 years of age and being female.
- heat intolerance
- muscle weakness/wasting
- weight loss
- increased appetite
- non-painful goitre (swelling of the thyroid gland)
- tachycardia (high heart rate - above 100 beats per minute at rest in adults)
Sequence of events:
- Iodine deficiency leading to decreased T4 production.
- Induction of thyroid cell hyperplasia due to low levels of T4. This accounts for the multinodular goitre appearance.
- Increased replication predisposes to a risk of mutation in the TSH receptor.
- 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. Another treatment option in recent years (2013) is ethanol ablation of the nodules.
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.
- de Rooij, A; Vandenbroucke, JP; Smit, JW; Stokkel, MP; Dekkers, OM (2009). Clinical outcomes after estimated versus calculated activity of radioiodine for the treatment of hyperthyroidism: systematic review and meta-analysis.journal=European journal of endocrinology 161 (5). pp. 771–777. doi:10.1530/EJE-09-0286. PMID 19671708.
- Krohn, K; Fuhrer, D; Bayer, Y; Eszlinger, M; Brauer, V; Neumann, S; Paschke, R (2005). "Molecular pathogenesis of euthyroid and toxic multinodular goiter.". Endocrine reviews 26 (4): 504–524. doi:10.1210/er.2004-0005. PMID 15615818.
- Reid, JR; Wheeler, SF (2005). "Hyperthyroidism: diagnosis and treatment.". American family physician 72 (4): 623–630. PMID 16127951.
- A.D.A.M. Medical Encyclopedia (2012). "Toxic nodular goiter". U.S. National Library of Medicine. Retrieved 30 January 2013.
- Plummer's disease eponymously named after Henry Stanley Plummer at Who Named It?