Hashimoto’sDisease
Hashimoto’sDisease
• AkaChronicLymphocyticThyroiditis• Autoimmunediseasecausingprimaryhypothyroidism• PrimarycauseofhypothyroidisminUS
• 1in1000• ThirdmostprevalentautoimmunediseaseintheUS• Atleast 7timesmorecommoninwomenthanmen
Hakaru Hashimoto- 1912
• Firstrecognizedautoimmunedisease• DiscoveredbyJapanesespecialistHakaru Hashimoto• Publishedin1912
Symptoms
• Fatigue• Weightgain• Pale/puffyface• Feelingcold• Joint/musclepain• Constipation• Dry/thinninghair• Memoryproblems
Pathophysiology• Immunesystemattacksthethyroidgland,causinginflammationandpreventingitfromproducingthyroidhormones• T3=triiodothyronine• T4=thyroxine
• Autoantibodiesagainstthyroidperoxidase(TPO),thyroglobulin,TSHreceptorsattackfolliclesofthyroidgland
• InvasionofthyroidtissuebyT-lymphocytes
• ThyroidStimulatingHormone(TSH)increasesbypituitaryasT4decreases(nonegativefeedback)
• Enlargementofthethyroidisduetolymphocyticinfiltrationandfibrosisratherthantissuehypertrophy.
Hashimoto’sHistology
• Massiveinfiltrationoflymphocytes+plasmacellsintothyroidgland• Germinalcentersform(notpresentinnormalthyroidgland)• Thyroidfolliclesdisappear(presentinnormalthyroidtoproduceT3/T4)
ContrastwithGrave’sDisease(Hyperthyroid)
• Bothdiseasesresultinantibodiesattackingthyroidgland,preventingnegativefeedback
• Bothcausegoiter• Hashimoto’sisduetoinfiltrationbylymphocytes• Grave’sisduetoexcessiveT3/T4production
• Onecanprogresstotheother (oftenGraves->Hashimoto’s)
RiskFactors
• Familyhistory• HLA-DR5gene• CTLA-4gene(CytotoxicT-lymphocyteAntigen-4)=negativeregulationofTCells
• AlsoassociatedwithType1DM
• EnvironmentalFactors• Highiodine intake?• Seleniumdeficiency
• ChromosomalDisorders• TurnersSyndrome,DownSyndrome, Klinefelter Syndrome
• OtherAutoimmuneDiseases
Diagnosis
• History+Physicalexam+Presenceofagoitre
• BloodtestingforThyroid-Stimulatinghormone(TSH),freeT3/T4• HighTSHandlowT3/T4
• Presenceofantibodies(anti-Tg,anti-TPO,TPOab)
• FineNeedleAspirationtoexcludemalignancy
• Oftenmisdiagnosedasdepression,chronicfatiguesyndrome,anxietydisorder,PMS,…
Treatment
• ThyroidHormoneReplacements(syntheticT4)• Levothyroxine,triiodothyronine, desiccatedthyroidextract• Oral,onceperdaytokeepTSHunder3.0• Mustbechecked~every6months(toomuchcancauseosteoporosisandarrhythmias)
• Other:• Selenium• Low-levellasertherapy• Glutenfreediet
Prognosis
• Excellentwithmedication• 5%progresstothyroidfailureeveryyear• RarelyprogressestohyperthyroidBasedow-GravesDisease• HigherriskofBcelllymphoma• Susceptibletootherautoimmunediseases• Vitiligo,Rheumatoidarthritis,Addison’s disease,DMType1,PerniciousAnemia,CeliacDisease,Autoimmune Hepatitis
Sources
• https://en.wikipedia.org/wiki/Hashimoto's_thyroiditis#Pathophysiology
• http://www.niddk.nih.gov/health-information/health-topics/endocrine/hashimotos-disease/Pages/fact-sheet.aspx
• http://www.omim.org/entry/140300
• http://www.omim.org/geneMap/8/401?start=-3&limit=10&highlight=401
• http://ghr.nlm.nih.gov/gene/HLA-DRB1
• http://emedicine.medscape.com/article/120937-overview