| Kitsize | 96 |
| Method | IRMA(CT) |
| Incubationtime | 1x2h |
| Standardrange | 1-120µIU/mL |
| Specimen/Volumes | 50µLserum,plasma |
| Substrate/isotope | 125I<350kBq |
| RegulatoryStatus: | EU:CE |
hGHisapolypeptidehormone(molecularweight21,500Da)producedbytheacidophilcellsoftheanteriorpituitaryunderthecontroloftwomainsubstancesfromthemedianeminence:Growth-hormoneReleasingFactor(GRF)andaninhibitoryagent,somatostatin.Dopaminergic,adrenergicandSEROtoninergicneuroendocrinepathwaysalsoplayanimportantroleinthecontrolofhGHsecretion.ExcitatorystimuliofhGHsecretionincludehypoglycemia,exercise,fasting,mealswithahighproteincontent,deepsleep,stress,glucagon,LDopa,aminoacids,etc.
Inhibitorystimuliincludeglucose,cortisol,hGHandfreefattyacids.Becauseofitsshortplasmahalflife(±25minutes)andofthefrequentexcitatoryorinhibitorystimuli,hGHdisplaysfrequentandlargevariationsofconcentrationinserum.OneofthemainphysiologicalfunctionsofhGHistoactontheliverandothertissuestoproduceSomatomedins,whichinturninducegrowthbydirectactionontargettissues.IncontrasttohGH,theconcentrationofsomatomedininserumiskeptstablebyvirtueofbeinglargelyboundtocirculatingplasmaproteins.
ClinicalapplicationofGrowthhormomeIRMA(CT)
- GrowthretardationhGHhyposecretionisoneofthevariouscausesofsmallstatureinchildren.SerumhGHmeasurementwithahighlysensitiveassay,especiallyfollowingaprovocativestimulus(absenceofresponse),isanimportantwaytoestablishthisdiagnosisbecausethisgroupofpatientscanbetreatedbyadmiNISTrationofhGH.
- HypopituitarismSerumhGHmeasurementisalsoanindexofpituitaryfunctionwhenhypopituitarism(eitheridiopathicorduetotumourandsurgery)issUSPected.
- GigantismandacromegalySerumhGHmeasurement,especiallyfollowingaprovocativeinhibitorytest(absenceofresponse),isanimportantwaytoestablishthediagnosisofhGHhypersecretionduetoacidophilicpituitarytumour.Thisresultsingigantisminchildrenandacromegalyinadults.BothofthesedisordersmaybetreatedbysurgeryorrADIation.
