TheThyroglobulinELISAisanindirectsolidphaseenzymeimmunoassayforthequantitativedetectionofthyroglobulin(hTg)inhumanserum.
Thyroglobulin(Tg)isaglycoproteinofhighmolecularweight(660kDa)localizedwithinthecolloidofthethyroidfollicle.Itplaysanessentialroleinthestorageofiodineandactsassubstratumforthesynthesisofiodinatedthyroidhormonesthyroxine(T4)and3,5,3`-triiodothyronine(T3).Elevatedthyroglobulinserumconcentrationshavebeenreportedinvariousthyroiddiseases,suchas,hyperthyroidism,non-toxicgoiter,thyroiditisanddifferenciatedthyroidcarcinoma.ThemainindicationoftheTgdetermination,howeveristhepostoperativemonitoringofdifferentiatedthyroidcarcinoma.Itsclinicalvalueistheearlydetectionandexclusionofmetastasesortumorrelapsesandthefollow-upofrADIoiodinetreatments.SerumTgisnondetectableinpatientswhounderwenttotalthyroidectomyincludingablationbyradioiodineandarefreeofmetastasesandtumor.ThesepatientsintruecompleteremissionwillnotdisplayTglevels,evenbyendogenousTSHstimulation.ConsequentlydetectableTgvaluesinthesegroupofpatientsareanimportantindicationforstillexistingornewlydevelopedneoplasia.ParticularlyifthesedetectableTgvaluesareincreasingunderaTSH-suppressivethyroidhormonetreatment(Tgprofiles).Incontrast,thyroglobulinlevelsinpatientswithmedullarycarcinomaorundifferentiatedtumorsremainwithinthenormalrange.Sincethyroglobulinlevelscouldalsobeelevatedinotherbenignthyroiddiseases,thistestisnotacriteriaforthediagnosisofmalignantthyroidtumors.DeterminationofthyroglobulinisofprognosticvalueinGraves`diseasepatientsundergoingtherapy.SignificantlyelevatedTglevelsattheendofathyrostatictherapyareindicationforahigherriskofrelapse,whereaspatientswithcontinuouslowthyroglobulinconcentrationstendtocontinualrecovery.