ForthedirectquantitativedeterminationofReverseTriiodothyronine(rT3)inhumanserumandplasmabyanenzymeimmunoassay.
3,3’,5’-Triiodo-L-thyroninealsoknownasreversetriiodothyronineorreverseT3(rT3),differsfrom3,3’,5’-Triiodo-L-thyronine(T3)inthepositionsoftheiodineatomsinthemolecule.ThemajorityofcirculatoryrT3issynthesizedbyperipheraldeiodinationofthyroxine(T4).BothT3andrT3bindtothyroidhormonereceptors,butincontrasttoT3,rT3hasnotbeenfoundyettostimulatereceptormetabolicactivity;itblocksreceptorsitesfromT3activation.TheratioofrT3toT3isavaluablebio
Markerofthemetabolismandfunctionofthyroidhormonesbecausetheprocessof5’monodeiodinationthatconvertsT4toT3andrT3to3,3’-T2isinhibitedinanumberofnon-thyroidalconditionssuchasfasting,anorexianervosa,malnutrition,diabetesmellitus,stress,severetraumaorinfection,hemorrhagicshock,hepaticdysfunction,pulmonarydiseasesandothers.Thisscenarioisknownas"Sickeuthyroid"syndromeor“LowT3”syndrome.
AnelevatedratioofrT3overT3isthereforeindicativeof"sickeuthyroid"syndromeandhelpstoexcludeadiagnosisofhypothyroidism,particularlyincriticallyillpatients1-9.
TheconcentrationofrT3couldbehighinpatientsonthefollowingmedications:amiodarone,dexamethasone,propylthiouracil,ipodate,propranolol,andtheanesthetichalothane.TheconcentrationofrT3couldbelowinpatientsonDilantin,whichdecreasesrT3duetoitsdisplacementfromthyroxine-bindingglobulinandtherefore
generatesanexcessiveclearanceofrT3.
ForconcretedatapleaseconsulttheInstructionforUseinthedownloadboxontherightside.