Enzymeimmunoassayforthein-vitro-diagnosticquantitativedeterminationofFreeTestosteroneinhumanserumandplasma.ThisassayisasecondgenerationassayforthemeasurementoffreeTestosteroneinserumandplasma.
Testosterone,aC19-Steroid,isthemosteffectivenaturalhormoneinthefamilyofandrogens.Inmales,itismainlyproducedintheLeydigcellsofthetestes,onlyasmallamountisproducedintheadrenalcortex.Onthewhole,adultmaleshave10to20foldhighertestosteroneplasmaconcentrationsthanfemales.Inthecirculation,themainpartoftestosteroneisboundtoplasmaproteinslikesexhormonebindingglobuline(SHBG)andalbumine.
TestosteroneisresponsIBLeforthedevelopmentofsecondarymalesexcharacteristicsanditsmeasurementsarehelpfulinevaluatingthehypogonadalstates.Inwomen,highlevelsoftestosteronearegenerallyfoundinhirsutismandvirilization,polycysticovaries,ovariantumors,adrenaltumorsandadrenalhyperplasia.Inmen,highlevelsoftestosteroneareassociatedtothehypothalamicpituitaryunitdiseases,testiculartumors,congenitaladrenalhyperplasiaandprostatecancer.
Lowlevelsoftestosteronecanbefoundinpatientswiththefollowingdiseases:hypopituitarism,Klinefelter"ssyndrome,testicularfeminization,OrchidectomyandCryptorchidism,enzymaticdefectsandsomeautoimmunediseases.
Testosteronecirculatesinthebloodboundtothreeproteins:sexhormonebindingglobulin(60-80%),albuminandcortisolbindingglobulin.Onlyabout1-2%ofthetotalcirculatingtestosteroneremainsunboundorfree.Eventhoughitisstillunderinvestigation,mostresearchersacceptthefreetestosteronedeterminationasameasureoftheBIOLOGicallyactivefraction.Freetestosteronedeterminationsarerecommendedtoovercometheinfluencescausedbyvariationsintransportproteinsonthetotaltestosteroneconcentration