ThehCGELISAisanenzymeimmunoassayforthequantitativeinvitrodiagnosticmeasurementofintacthumanchorionicgonadotropin(hCG)inserumorplasma.

ChorionicGonadotropin(hCG)isaglycoproteinhormonewhichisnormallyproducedbytheplacentaduringpregnancy.Afterconception,thehCGconcentrationincreasesrapidlytoreachapeakneartheendofthefirsttrimester.Highconcentrationsareobservedthroughoutpregnancy.Afterdelivery,hCGlevelsfallrapidlyandbecomeundetectableafterafewdays.
StructurallyintacthCGmoleculesarecomposedofanalphaandabetasubunitwithamolucularweightof38.4kDa.Thealphasubunitisnearlyidenticaltothealphasubunitsofotherglycoproteinhormones,suchasThyroidStimulatingHormone(TSH),LuteinizingHormone(LH),andFollicleStimulatingHormone(FSH):ThedifferencesinthebetasubunitoftherespectivehormonesaccountfortheirBIOLOGicalspecificityandimmunochemicaldistinctiveness.MonoclonalantibodiesrecognizinguniquesitesonthebetachainofthehCGmoleculeareessentialfordifferentiationbetweenhCGandLH,FSHandTSH.

hCGAssaysareusedfortheearlydetectionofpregnancy.
1.InadditiontotheelevatedhCGlevelsduringpregnancy,highconcentrationsofhCGmaybeassociatedwithneoplasmsoftrophoblasticandnontrophoblasticoriginsuchashydatiformmole,chorionepithelioma,embryonalcellcarcinoma,andmanyothers.

2.HCGiscommonlyelevatedindifferenttesticulartumorsandisthususedasatumorMarkerfortesticulartumorsincombinationwithAFP.ThereisagoodcorrelationbetweenchangesinhCGlevelsandresponsetotherapy.

3.Extragonadalgerm-cellcancersintheabsenceofclinicallyorultrasonographicallydetectabletesticularabnormalitieshavebeeinobservedaswell.Over50%ofpatientswithmalignantinsulinomashaveelevatedhCGlevels:thehormoneisnotdetectedinassociationwithbenignadenomas.EctopicsecretionofhCGalsohavebeenfoundinasmallpercentageofpatientswithadenocarcinomaoftheovary,pancreasandstomach,hepatomas,andislet-cellcarcinomas.