Editing Hyperthyroidism (section)

== '''Toxic MNG (Plummer's Disease)''' ==

* An enlarged nodular thyroid     containing one or more autonomously functioning nodules leading to a state     of hyperthyroidism
** Second most common cause of      hyperthyroidism
* Risk factors
** Older age - uncommon      <50yo
** Iodine deficient region
** Female (5:1)
* Pathophysiology
** Autonomously functioning      nodules occur after a mutation in TSH receptor gene leads to constitutive      synthesis and secretion of thyroid hormones
** Rarely malignant, do not      generally require biopsy
* Presentation
** Develops slowly from      subclinical hyperthyroidism into thyrotoxicosis
* Workup
** TFTs and thyroid Abs
** Exclude Graves and      autoimmune thyroiditis
** Nuclear scintigraphy -      first-line imaging
*** Identifies location and       distribution of autonomously functioning nodules and/or regions
** USS
*** Also useful to characterise       any nodules that may require biopsy
* Management - three options
** Antithyroid drugs -      virtually never used for definitive treatment, but can help as pre-op      preparation
*** Use methimazole before both       RAI and surgery, with or without beta blockade
*** Start on carbimazole 5mg       daily
** Radioactive iodine -      effective, but generally takes about 6 months to work. Especially good in      settings of high operative risk. Second dose necessary in about 25%.
*** Most common option in USA
*** Need higher dose than in       Graves disease because of lower uptake
** Surgery - prompt, permanent      cessation of hyperthyroidism (within a month). Removal of Goitre.      Treatment of any nodules/malignancy. Will need thyroxine. Can be more      difficult operation than normal thyroidectomy due to size of goitre. Need      near-total or total thyroidectomy.