ROLE OF ANTITHYROID AUTOIMMUNITY AS A PREDICTIVE BIOMARKER OF CHRONIC IMMUNE THROMBOCYTOPENIA

Background:Immunethrombocytopenia(ITP)isanacquiredimmune-mediateddisordercharac-terizedbyisolatedthrombocytopenia.PediatricITPpatientsarepronetodevelopautoantibod-iessuchasantithyroglobulin(TG)andantithyroperoxidase(TPO),evenintheabsenceofclinicalsignsofautoimmunedisease.Theaimofthismulticenterretrospectivestudywastoevaluate(1)theprevalenceofpositivityofantithyroidantibodies(TPOandTG)inalargecohortofpediatricpatientswithchronicITP;(2)theroleofautoimmunethyroiditisasaprognosticfactorforchronic-ityofITP.Procedure:Forthisretrospectivestudy,wecollecteddatafrompatientsdiagnosedasaffectedbychronicITPbetween2011and2014insixcentersbelongingtotheItalianAssociationofPediatricHaematologyandOncology(AIEOP).Results:Fromtheanalysisofdata,wefoundasignificantlyhigherprevalenceofantithyroidanti-bodiesinchildrenwithchronicITP(11.6%)thaninthepediatricpopulation(1.2%–1.3%).Nocorrelationhasbeenfoundbetweentheplateletcountandtheprevalenceofpositiveantithy-roidantibodiesatanydetectiontimeofthestudy.Conclusions:The results of our study demonstrated that (1) the prevalence of positivity forantithyroidantibodies(anti-TPOandanti-TG)inpediatricpatientswithchronicITPresultsissig-nificantlyhigherthaninthepediatricpopulation;(2)autoimmunethyroiditisdoesnotseemtoplayaroleasaprognosticfactorforchronicityofITPinpediatricpatients