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E26 Endocrinology
Thyroid Toronto Notes 2019 Toxic Adenoma/Toxic Multinodular Goitre
Etiology and Pathophysiology
• autonomous thyroid hormone production from a functioning adenoma that is hypersecreting T3 and T4 • maybesingular(toxicadenoma)ormultiple(toxicmultinodulargoitre[Plummer’sdisease])
Clinical Features
• goitrewithadenomatouschanges
• tachycardia,heartfailure,arrhythmia,weightloss,nervousness,weakness,tremor,andsweats • seenmostfrequentlyinelderlypeople,oftenwithpresentationofatrialfibrillation
Investigations
• low TSH, high T3 and T4
• thyroidscanwithincreasedRAIUinnodule(s)andsuppressionoftheremainderofthegland
Treatment
• initiatetherapywithPTUorMMItoattaineuthyroidstate
• usehighdoseradioactiveiodine(I-131)toablatehyperfunctioningnodules
• β-blockersoftennecessaryforsymptomatictreatmentpriortodefinitivetherapy • surgicalexcisionmayalsobeusedas1stlinetreatment
Thyrotoxic Crisis/Thyroid Storm
Definition
• medicalemergency–acuteexacerbationofallofthesymptomsofthyrotoxicosispresentinginalife- threatening state secondary to uncontrolled hyperthyroidism!
• rare,butseriouswithmortalityratebetween10-30%
Etiology and Pathophysiology
• oftenprecipitatedbyinfection,trauma,orsurgeryinahyperthyroidpatient
Differential Diagnosis
• sepsis,pheochromocytoma,malignanthyperthermia,drugoverdose,neurolepticmalignantsyndrome
Clinical Features
• hyperthyroidism
• extremehyperthermia(≥40°C),tachycardia,vomiting,diarrhea,vascularcollapse,hepaticfailurewith
jaundice, and confusion
• mentalstatuschangesrangingfromdeliriumtocoma
Laboratory Investigations
• increased free T3 and T4, undetectable TSH
• ±anemia,leukocytosis,hyperglycemia,hypercalcemia,elevatedLFTs
General Measures
• fluids,electrolytes,andvasopressoragentsshouldbeusedasindicated
• acoolingblanketandacetaminophencanbeusedtotreatthepyrexia
• propranolol or other β-blockers that additionally decrease peripheral conversion of T3 → T4 can be
used, but should be used with caution in CHF patients as it may worsen condition
Specific Measures
• PTUistheanti-thyroiddrugofchoiceandisusedinhighdoses
• giveiodide,whichacutelyinhibitsthereleaseofthyroidhormone,onehourafterthefirstdoseofPTU
is given
■ Sodium iodide 1 g IV drip over 12h q12h
OR
■ Lugol’s solution 2-3 drops q8h
OR
■ Potassium iodide (SSKI) 5 drops q8h
• dexamethasone2-4mgIVq6hforthefirst24-48h;lowersbodytemperatureandinhibitsperipheral conversion of T3 → T4
Prognosis
• probably<20%mortalityrateifrapidlyrecognizedandtreated