Andersons pediatric cardiology 2279

Dyslipidemia
Dyslipidemiasaredisorderscharacterizedbyabnormallipoproteinmetabolism
resultinginincreasedtotalcholesterol(TC),increasedlow-densitylipoprotein
cholesterol(LDL-C),increasedtriglyceride,and/ordecreasedhigh-density
lipoproteincholesterol(HDL-C).Theselipidabnormalitiescanbecausedby
geneticmutations,environmentalfactorssuchasdietandactivitylevel,or
secondarytootherprocessessuchaskidneydiseaseandorgan
transplantation.99,100
Themostimportantgeneticdyslipidemiatoconsiderisfamilial
hypercholesterolemia(FH),whichiscausedbyheterozygousorhomozygous
mutationsinthegeneencodingtheLDLreceptororrelatedproteins.FHislikely
whenthefastingLDL-Clevelis160mg/dLorgreaterinchildhoodor190
mg/dLorgreaterinadulthood,thereisapositivefamilyhistoryof
hyperlipidemiaorprematurecoronarydisease,andsecondarycauses(suchas
hypothyroidism)havebeenexcluded.101HeterozygousFHhasanestimated
prevalenceof1in250102intheUnitedStatesandacceleratesatherosclerotic
cardiovasculardiseaseriskbyupto30years,103whilehomozygousFHhasan
estimatedprevalenceof1in1millionto1in160,000andcausescardiovascular
diseaseeventsinchildhood.104FHhasthehighestprevalenceofallthegenetic
defectsthatcausesignificantprematuremortality,andthisformedthebasisof
earlyscreeningprogramsforchildhooddyslipidemia,asdescribedbelow.
Whenconsideringdyslipidemiainchildhood,itisimportanttounderstand
developmentalchangesinlipidlevelsthatoccurinhealthychildren.105,106Lipids
andlipoproteinlevelsstartlowatbirth,riseslowlyoverthefirst2yearsoflife,
andthenstabilizeuntilpuberty.Duringpuberty,cholesterollevelsdecrease
beforerisingagaininlateadolescenceandearlyadulthood.Inparticular,the
expecteddeclineincholesterollevelsduringpubertymustbeanticipatedwhen
interpretingandmanaginglipidsinthisagegroup.

SelectiveScreeningVersusUniversalScreening
forDyslipidemia

Therehasbeensignificantdebateontheroleofuniversalversusselective
screeningfordyslipidemiasinchildrenandadolescents.In1992,theNational
CholesterolEducationProgram(NCEP)ExpertPanelonBloodCholesterol
LevelsinChildrenandAdolescentsrecommendedtargetingscreeningto


childrenwithfamilyhistoryofearlycoronaryarterydisease,familyhistoryof
hypercholesterolemia,orunknownfamilyhistory.107Suchastrategyseeksto
identifychildrenwithFH.However,afterpublicationofthe1992NCEP
guidelines,newdatawerereviewedinthefollow-upAmericanAcademyof
PediatricsreportonLipidScreeningandCardiovascularHealthshowingthat
selectivescreeningmissedbetween30%and60%ofchildrenwith
dyslipidemias.108ChildrenwithFHmaynotbedetectedwiththisstrategyif
theirparentsareunawareofthefamilyhistory,andinfact,screeningchildren
hasbeenadvocatedasastrategytoidentifyadultrelativeswiththiscondition
sincethediagnosismaybemorestraightforwardinchildhood.Moreover,with
thecontinuedincreaseintheprevalenceofpediatricobesity,therehasbeena
shiftinthepatternsofchildhooddyslipidemiafromprimarilyisolatedelevated
LDL-CduetoFHtotheincreasinglycommonobesity-associatedpattern:
moderatelytoseverelyelevatedtriglycerides,decreasedHDL-C,andnormalto
mildlyelevatedLDL-C.Bothpatternsareassociatedwithaccelerated
atherosclerosis.Becausechildhooddyslipidemiaisidentifiable,tracksinto
adulthood,andisamenabletointervention,the2011NHLBIGuidelinesfor
CardiovascularHealthandRiskReductioninChildrenandAdolescents
recommenduniversalscreeningbeforepuberty(9to11yearsofage)andagain
afterpuberty(18to21yearsofage).98

RecommendedScreeningforDyslipidemia
Asmentionedabove,theNHLBIGuidelinesprovideage-specific
recommendationsforpediatricproviderstoscreenforcardiovasculardisease

riskfactorsincludingdyslipidemias.Thedocumentalsoprovidesguidanceon
reinforcinghealthylifestylehabitsandprovidingtreatmentstodecreasethese
riskfactors,startingininfancy.Fordyslipidemia,theGuidelinesrecommend:

■Universalscreeningat9to11yearsofage(before
puberty)andagainat18to21yearsofage(after
puberty)withrandomnon–HDL-Clevelorfasting
lipidprofile.
■Screeningfrom2to8yearsofageand12to16


yearsofagewithafastinglipidprofileonlyifthereis
apositivefamilyhistory,otherriskfactorsfor
cardiovasculardisease,oramoderate-orhigh-risk
condition.
■Noroutinelipidscreeningfrombirthto1yearof
age.
Theaboveguidelinesaredelineatedingreatdetailinthe2011NHLBI
CardiovascularRiskGuidelines,asmentioned.98Thereaderisreferredtothis
reviewforadditionaldetails.

FutureConsiderationsforDyslipidemia
Screening
In2016,theUnitedStatesPreventiveServicesTaskForcereviewedtheliterature
andconcludedthatthereisinsufficientevidencetoassessthebenefitof
universalversustargetedscreeningfordyslipidemiasinchildrenand
adolescents.109Thisconclusionwasbasedonalackoflarge,randomizedcontrol
trialsinthepediatricpopulationevaluatingtargetedversusuniversalscreening
fordyslipidemiaandeffectivenessofearlydetectionandtreatmenton
intermediateandlong-termoutcomes.Asmentionedabove,thelongtimeline

(decades),cost,andethicalconsiderationsofsuchstudiesinchildrenare
prohibitive.Modelingapproachesmayoffersomeinsightintothesequestions,
buttodatethesedataarelacking.
However,availabledataindicatethatinitiationofstatintherapyinchildren
andadolescentswithhighLDL-Cduetofamilialhypercholesterolemiarestores
endothelialfunctionandslowsorevenreversesprogressionofatherosclerosisas
indicatedbycarotidintimalmediathickness.110–113Importantly,multiplestudies
havedemonstratedthesafetyofstatintherapyinchildrenandadolescents.114
Furthermore,clinicaltrialdataindicatethatlifestylemodificationcanimprove
intermediateoutcomesinchildrenwithmultifactorialdyslipidemia.115Giventhe
relativelyhighprevalenceofFHastheprototypicalgeneticdyslipidemiaandthe
veryhighprevalenceofobesityinchildren,effectivedyslipidemiascreeningin
theyoungerpopulationswillcontinuetohaveanimportantroleindecreasing