TheDetectX^®UrinaryCreatinineDetectionkitsaredesignedtoquantitativelymeasurecreatinineinurinesamples.ANISTcalibratedcreatininestandardisusedtostandardizetheassay.SamplesarePipettedintoaclearmicrotiterplateandthecolorgeneratingreactionisinitiatedwiththesuppliedno-mixDetectXCreatinineReagent,whichispipettedintoeachwell.Aftera30minuteincubationatroomtemperaturethecolorisreadat490nm.

Creatinine(2-amino-1-methyl-5H-imadazol-4-one)isametaboliteofphosphocreatine(p-creatine),amoleculeusedasastoreforhigh-energyphosphatethatcanbeutilizedbytissuesfortheproductionofATP.Creatineeithercomesfromthedietorsynthesizedfromtheaminoacidsarginine,glycine,andmethionine. Creatineandp-creatineareconvertednon-enzymaticallytothemetabolitecreatinine,whichdiffusesintothebloodandisexcretedbythekidneys.Invivo,thisconversionappearstobeirreversIBLeandinvitroitisfavoredbyhighertemperaturesandlowerpH.Creatinineformsspontaneouslyfromp-creatine.Undernormalconditions,itsformationoccursataratethatisrelativelyconstantandasintra-individualvariationis <15%fromdaytoday,creatinineisausefultoolfornormalizingthelevelsofothermoleculesfoundinurine.