Rev. Bras. Hematol. Hemoter. vol.38 número4

rev bras hematol hemoter. 2016;38(4):283–284

w w w . r b h h . o r g

Revista

Brasileira

de

Hematologia

e

Hemoterapia

Brazilian

Journal

of

Hematology

and

Hemotherapy

Scientific

Comment

Platelet

and

reticulocyte

new

parameters:

why

and

how

to

use

them?

夽

Helena

Zerlotti

Wolf

Grotto

a_{UniversidadeEstadualdeCampinas(UNICAMP),Campinas,SP,Brazil}

b_{SysmexLatinAmerica&TheCaribbean,SãoPaulo,SP,Brazil}

The evolution of automation in hematology has enabled greaterreliabilityandaccuracyintheresultsofthecomplete bloodcount(CBC)andtheimplementationofnew technolo-gieshasstreamlinedthelaboratoryroutine,optimizingthe timetorelease tests. Moreover,newlaboratoryparameters havebeenrecognizedasauxiliariestorecognizesomeclinical conditions.

Fromthefirstplateletcountperformedinachamber devel-opedbyNeubauerin19241_{tothepresentday,therehavebeen}

increasingimprovementsinthetechnologyusedtoidentify and quantify platelets.The newgeneration of hematology analyzersaremoreaccuratetoidentifycells,providing reli-abilityinthemeasurementofplateletsparticularlyincasesof severethrombocytopenia.Inaddition,theuseoffluorescent markersspecificforplateletsallowsthedetectionofpossible interference,forexamplebydecreasingthepossibilityofcases offalsethrombocytosis.2

Aspectsrelatedtotheidentificationofimmatureplatelets, termedreticulatedplatelets (RP),datebackto1969.Nucleic acid dyesallowedthe detection ofyounger platelets using anopticalmicroscopy.3 _{Thiazoleorangedyeflowcytometry}

andthestrategyofthe‘gate’wereintroducedlaterfor iden-tifyingRP.4,5_{Morerecentlysomehematologicanalyzershave}

madeitpossibletodetectnewly-releasedimmatureplatelets. Themainclinicalapplicabilityoftheimmatureplatelet frac-tion(IPF)istheevaluationofthrombopoieticactivity inthe bone marrow. An elevated number of immature circulat-ingplatelets isobservedinthrombocytopeniaofperipheral origin causedbyexcessive consumption ofplatelets,while

DOIoforiginalarticle:http://dx.doi.org/10.1016/j.bjhh.2016.07.001.

夽

SeepaperbyMorkisetal.inRevBrasHematolHemoter.2016;38(4):310–313.

∗ _{Correspondingauthorat:SysmexLatinAmericaandTheCaribbean,RuadoParaíso148,cj31,CEP04103-000,SãoPaulo,SP,Brazil.}

E-mails:lenagrotto@gmail.com,helenagrotto@sysmex.com.br

thrombocytopeniacausedbyinadequateplateletproduction ischaracterizedbyareducednumberofimmatureplatelets enteringintothecirculation.6–8

Another IPFapplication isthemonitoringofthe throm-bocytopenic phase after chemotherapy and the transplant of precursor cells.7,8 _{As younger platelets apparently have}

greaterthromboticpotentialandaremetabolicallyand enzy-matically more active than adult platelets, some studies proposemonitoringoftheRPorIPFasindicatorsofriskfor acutecoronarysyndromeandotherinflammatoryand throm-boticconditions.9

Thesametechnologicalevolutionintermsofaccuracy,and availabilityofnewparameterswasobservedintheerythroid series.Thereticulocyte(RTC)countisclinicallyimportantboth for the pathophysiological classification ofanemia, and to monitormarrowresponseaftertherapeuticinterventions.10

However,for along timethe RTC countwas underusedin the clinical and laboratory practicedue tothreemain fac-tors: technical limitations inthe detection of the cell, the imprecision of the manual microscopic method, and high coefficientofvariationsincounts.Withtheadventof automa-tion,thedetectionandquantificationofthesecellsaremuch more accurate and reliable, returning credibility and clini-calvaluetoRTCenumeration.Similartowhatoccurredwith platelets,newparametersrelatedtothedegreeof immatu-rity ofthese precursors ofred blood cells were introduced by several hematologicanalyzer manufacturers. Initially, it waspossibletosubdividethereticulocytepopulationin dif-ferent degreesofmaturityaccordingtothecontent ofRNA insidethe cell:moreimmaturereticulocyteshave ahigher

http://dx.doi.org/10.1016/j.bjhh.2016.08.001

284

fluorescenceintensitythanmaturecells.Theimmature retic-ulocytefraction(IRF)providesthesameinformationobtained bythereticulocytecountregardingtheevaluationofbone mar-rowresponsetoanemiaorerythropoieticactivityingeneral.10

Theadvantageistheprecocityoftheinformationprovidedby IRFcomparedtotheRTCcount.Incasesofregenerative ane-miaorresponsetoreplacementtherapy,elevationsintheIRF valueprecedetheincreaseintheabsolutenumberof retic-ulocytesbyseveraldays.Forthisreason,itissuggestedthat theIRF shouldbeusedasanaidintheevaluationofbone marrowresponseduringmobilizationofhematopoietic pre-cursorcells,11_{orasapredictorofrecoveryfromneutropenia}

inautologoustransplantation.12

Themeasurementofthecontentofhemoglobinof reticu-locytes(CHrorRet-He)reflectsthesynthesisofhemoglobinin marrowprecursors,andallowsthedetectionofearlystages ofirondeficiency.13_{Thisparameterhasbeenidentifiedasan}

auxiliaryinthedifferentialdiagnosisofanemias.14_Themain

advantagesofRet-Hearethatitisreleasedatthesametime astheCBC,anditismoreaccuratethanbiochemical mark-ers,suchas ferritinand transferrin saturation indetecting iron-deficienterythropoiesisinpatientswithinflammationor anemiaofchronicdisease.10

In the practice, the determination of Ret-He has been morewidely used in patients with chronic kidney disease undergoingadialysisregimeandrecombinanthuman eryth-ropoietin(rHuEPO).15,16 _{Undertheseconditionssuitableiron}

intakeisimperativeforadequate erythropoiesis. Biochemi-caldosageshaveshownlimitationsintheevaluationofiron statusinthisgroupofpatients,becausetheycansufferany effectofinflammatoryactivity.Reticulocytehemoglobin con-tentmeasurementisincorporatedintotheNational Kidney FoundationKidneyDiseaseOutcomesQualityInitiative (NKF-K/DOQI)guidelinestomonitorrHuEPOtherapy.17

Limitationsinthewideruseofthesenewhematological parametersarerelatedtothelackofstandardizationandthe establishmentofreferencevaluesforthenormalpopulation, Therefore, sincethe technologiesand the nomenclature of newindexesvaryaccordingtothemanufacturer,itisdifficult tocomparenumericresultsobtainedfromdifferentanalyzers. Inthe study reportedbyMorkiset al.,18 _132samplesof

apparently healthy individuals were evaluated in order to establish the reference ranges forIRF, Ret-He and IPF. The observedresultsareinagreementwithpublisheddatagiving greater reliability inthe investigation of the clinical appli-cationsof the parameters, and in the analysis of possible alterations foundon comparing resultsfrom patients with valuesobtainedinthenormalpopulation.

Theestablishmentofreferencevaluesisapracticethat shouldbeadoptedwheneveranewtestisintroducedinthe laboratoryroutine.Inaddition,aharmonizationisneededfor newparametersandindicesbetweendifferentanalyzers.

Conflicts

of

interest

TheauthorisaMedicalAdvisorofSysmexLatinAmericaand theCaribbean.Thatcompanyproducesthehematologic anal-yserusedinthestudy.

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