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Toronto Notes 2019 Thyroid Endocrinology E29 Labs
• initially decreased free T3 followed by decreased TSH and finally decreased free T4
Treatment
• treattheunderlyingdisease;thyroidhormonereplacementworsensoutcomes
• thyroidfunctiontestsnormalizeoncepatientiswell(initiallywithatransientincreaseinTSH)
Non-Toxic Goitre
Definition
• generalizedenlargementofthethyroidglandinaeuthyroidindividualthatdoesnotresultfrom inflammatory or neoplastic processes
Pathophysiology
• theappearanceofagoitreismorelikelytopresentduringadolescence,pregnancy,andlactationdueto increased thyroid hormone requirements
■ early stages: goitre is usually diffuse
■ later stages: multinodular non-toxic goitre with nodule, cyst formation and areas of ischemia,
hemorrhage, and fibrosis
Etiology
• iodinedeficiencyorexcess
• goitrogens:brassicavegetables(e.g.turnip,cassava)
• drugs:iodine,lithium,para-aminosalicylicacid
• anydisorderofhormonesynthesiswithcompensatorygrowth • peripheralresistancetothyroidhormone
Treatment
• removegoitrogens
• radioiodinetherapy(needveryhighdosesgivenlowiodineuptake,usedaslastresort)
• suppressionwithL-thyroxine(rarelydone)
• surgerymaybenecessaryforseverecompressivesymptoms;however,thesepatientsareoften
asymptomatic
Complications
• compressionofneckstructurescausingstridor,dysphagia,pain,andhoarsenessofvoice
• multinodulargoitremaybecomeautonomousleadingtotoxicmultinodulargoitreandhyperthyroidism
Thyroid Nodules
Definition
• clearlydefineddiscretemass,separatedfromthethyroidparenchyma
• palpablenodulesarefoundinapproximately5%ofwomenand1%ofmen
Etiology
• benigntumours(e.g.colloidnodule,follicularadenoma)
• thyroidmalignancy
• hyperplasticareainamultinodulargoitre
• cyst:truethyroidcyst,areaofcysticdegenerationinamultinodulargoitre
Investigations
sTSH
Low TSH Normal/elevated TSH
Thyroid scan
Thryoid ultrasound and biopsy Treat hyperthyroidism
Thyroid ultrasound and biopsy
Hot nodule
No biopsy Treat hyperthyroidism
Cold nodule
Figure10.Approachtotheevaluationofathyroidnodule AdaptedfromDr.JGoguen,UniversityofToronto,MMMD2013
Thyroid Malignancies
• seeOtolaryngology,OT37