TheLHUrineELISAisanenzymeimmunoassayforthequantitativemeasurementofLHinurine.
ThistestisusedtodetectthemidcycleLHsurgeinurine,whichisanaidinpredictingthetimeofovulation.

SUMMARYANDEXPLANATION
Luteinizinghormone(LH)isproducedinbothmenandwomenfromtheanteriorpituitaryglandinresponsetoluteinizinghormone-releasinghormone(LH-RHorGn-RH),whichisreleasedbythehypothalamus.LH,alsocalledinterstitialcell-stimulatinghormone(ICSH)inmen,isaglycoproteinwithamolecularweight
ofapproximately30.000daltons.Itiscomposedoftwononcovalentlyassociateddissimilaraminoacidchains,alphaandbeta.Thealphachainissimilartothatfoundinhumanthyroid-stimulatinghormone(TSH),folliclestimulatinghormone(FSH),andhumanchorionicgonadotropin(hCG).Thedifference
betweenthesehormoneslieintheaminoacidcompositionoftheirbetasubunits,whichaccountfortheirimmunologicaldifferentiation.

ThebasalsecretionofLHinmenisepisodicandhastheprimaryfunctionofstimulatingtheinterstitialcells(Leydigcells)toproducetestosterone.ThevariationinLHconcentrationsinwomenissubjecttothecomplexovulatorycycleofhealthymenstruatingwomen,anddependsuponasequenceofhormonalevents
alongthegonado-hypothalamic-pituitaryaxis.ThedecreaseinprogesteroneandestrADIollevelsfromthepreceedingovulationinitiateseachmenstrualcycle.Asaresultofthedecreaseinhormonelevels,thehypothalamusincreasesthesecretionofgonadotropin-releasingfactors(GnRF),whichinturnstimulatesthepituitarytoincreaseFSHproductionandsecretion.TherisingFSHlevelsstimulateseveralfolliclesduringthefollicularphase,oneofthesewillmaturetocontaintheegg.Asthefollicledevelops,estradiolissecreted,slowlyatfirst,butbyday12or13ofanormalcycleincreasingrapidly.LHisreleasedasaresult
ofthisrapidestradiolrisebecauseofdirectstimulationofthepituitaryandincreasingGnRFandFSHlevels.Theseeventsconstitutethepre-ovulatoryphase.
Ovulationoccursapproximately12to18hoursaftertheLHreachesamaximumlevel.Aftertheeggisreleased,corpusluteumisformedwhichsecretesprogesteroneandestrogen-twofeedbackregulatorsofLH.Thelutealphaserapidlyfollowsthisovulatoryphase,andischaracterizedbyhighprogesteronelevels,asecondestradiolincrease,andlowLHandFSHlevels.LowLHandFSHlevelsaretheresultofthenegativefeedbackeffectsofestradiolandprogesteroneonthehypotalamic-pituitaryaxis.
Afterconception,thedevelopingembryoproduceshCG,whichcausesthecorpusluteumtocontinueproducingprogesteroneandestradiol.Thecorpusluteumregressesifpregnancydoesnotoccur,andthecorrespondingdropinprogesteroneandestradiollevelsresultsinmenstruation.Thehypothalamusinitiates
themenstrualcycleagainasaresultoftheselowhormonelevels.
PatientssufferingfromhypogonadismshowincreasedconcentrationsofserumLH.Adecreaseinsteroidhormoneproductioninfemalesisaresultofimmatureovaries,primaryovarianfailure,polycysticovarydisease,ormenopause;inthesecases,LHsecretionisnotregulated.Asimilarlossofregulatory
hormonesoccursinmaleswhenthetestesdevelopabnormallyoranorchiaexists.HighconcentrationsofLHmayalsobefoundinprimarytesticularfailureandKlinefeltersyndrome,althoughLHlevelswillnotnecessarilybeelevatedifthesecretionofandrogenscontinues.IncreasedconcentrationsofLHarealso
presentduringrenalfailure,cirrhosis,hyperthyroidism,andseverestarvation.
AlackofsecretionbytheanteriorpituitarymaycauselowerLHlevels.Asmaybeexpected,lowlevelsmayresultininfertilityinbothmalesandfemales.LowlevelsofLHmayalsobeduetothedecreasedsecretionofGnRHbythehypothalamus,althoughthesameeffectmaybeseenbyafailureoftheanteriorpituitarytorespondtoGnRHstimulation.LowLHvaluesmaythereforeindicatesomedysfunctionofthepituitaryorhypothalamus,buttheactualsourceoftheproblemmustbeconfirmedbyothertests.
Inthedifferentialdiagnosisofhypothalamic,pituitary,orgonadaldysfunction,assaysofLHconcentrationareroutinelyperformedinconjunctionwithFSHassayssincetheirrolesarecloselyinterrelated.
FurThermore,thehormonelevelsareusedtodeterminemenopause,pinpointovulation,andmonitorendocrinetherapy.