TheCortisol(Urine)ELISAisacompetitiveimmunoenzymaticcolorimetricmethodforquantitativedeterminationoffreecortisolconcentrationinUrine.

CortisolisasteroidhormonereleasedfromtheadrenalcortexinresponsetoahormonecalledACTH(producedbythepituitarygland),itisinvolvedintheresponsetostress;itincreasesbloodpressure,bloodsugarlevels,maycauseinfertilityinwomen,andsuppressestheimmunesystem.
Cortisolactsthroughspecificintracellularreceptorsandhaseffectsinnumerousphysiologicsystems,includingimmunefunction,glucose-counterregulation,vasculartone,substrateutilizationandbonemetabolism.Cortisolisexcretedprimarilyinurineinanunbound(free)form.Cortisolisbound,inplasma,fromcorticosteroid-bindingglobulin(CBG,transcotin),withhighaffinity,andfromalbumin.Onlyfreecortisolisavailabletomostreceptors.
Thesenormalendogenousfunctionsarethebasisforthephysiologicalconsequencesofchronicstress-prolongedcortisolsecretioncausesmusclewastage,hyperglycaemia,andsuppressesimmune/inflammatoryresponses.Thesameconsequencesarisefromlong-termuseofglucocorticoiddrugs.
Thefreecortisolfractionrepresentsthemetabolicallyactivecortisol.Innormalconditions,lessthen1%itcomesexcreteinurines.Inpathologicalconditions(syndromeofCushing)thelevelsoffreeurinarycortisolareelevate,becausetheCBGdon’tboundtheplasmaticcortisolinexcessanditwasremovewithurines.Duringpregnancyorestro-progestogentreatmentanincreaseofplasmaticcortisolcausedbyanincrementoftheproductionofthetransportprotein,butthelevelsoffreeurinarycortisolresultsnormaltoindicatecorrectadrenalfunctionality.
Thistestisveryusefultoestimatetherealadrenalfunction,becauseitmeasurethefreecortisol,itisthemetabolicallyactiveform.MoreoverthemeasurementoffreeurinarycortisolisthebetterparameterforthediagnosisoftheCushing’ssyndrome.