| Kitsize | 96 |
| Method | RIA(CT) |
| Incubationtime | 1x1hwithshaking |
| Standardrange | 12.8-500nmol/L |
| Specimen/Volumes | 20µLSerum,Plasma |
| Substrate/isotope | 125I<111kBq |
| RegulatoryStatus: | EU:CE |
RadioimmunoassayfortheinvitroquantitativemeasurementofhumanThyroxine(T4)inserum.
BIOLOGicalactivity
L-Thyroxine(T4)isahormonethatissynthesizedandstoredinthethyroidgland.ProteolyticcleavageoffollicularthyroglobulinreleasesT4intothebloodstream.Greaterthan99%ofT4isreversIBLyboundtothreeplasmaproteinsinblood–thyroxinebindingglobulin(TGB)binds70%,thyroxinebindingpre-albumin(TBA)binds20%,andalbuminbinds10%.Approximately0.03%ofT4isinthefree,unboundstateinbloodatanyonetime.
Clinicalapplications
Diseasesaffectingthyroidfunctionmaypresentawidearrayofconfusingsymptoms.MeasurementoftotalT4byimmunoassayisthemostreliableandconvenientscreeningtestavailabletodeterminethepresenceofthyroiddisordersinpatients.IncreasedlevelsofT4havebeenfoundinhyper-thyroidismduetoGrave’sdiseaseandPlummer’sdiseaseandinacuteandsubacutethyroiditis.LowlevelsofT4havebeenassociatedwithcongenitalhypothyroidism,myxedema,chronicthyroiditis(Hashimoto’sdisease)andwithsomegeneticabnormalities.
