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2023-05-06 17:32:17

NATIONALHEALTHANDNUTRITIONEXAMINATIONSURVEY2013-2014DATADOCUMENTATION,CODEBOOK,ANDFREQUENCIESMETHYLMALONICACID(MMA_H)DATAFILE:MMA_H.XPTFIRSTPUBLISHED:OCTOBER2018LASTREVISED:NACOMPONENTDESCRIPTIONTHESEDATAWILLBEUSEDTOESTIMATEDEFICIENCIESANDTOXICITIESOFSPECIFICNUTRIENTSINTHEPOPULATIONANDSUBGROUPS,TOPROVIDEPOPULATIONREFERENCEDATA,ANDTOESTIMATETHECONTRIBUTIONOFDIET,SUPPLEMENTS,ANDOTHERFACTORSTOSERUMLEVELSOFNUTRIENTS.DATAWILLBEUSEDFORRESEARCHTOFURTHERDEFINENUTRIENTREQUIREMENTSASWELLASOPTIMALLEVELSFORDISEASEPREVENTIONANDHEALTHPROMOTION.ELIGIBLESAMPLEEXAMINEDPARTICIPANTSAGED19YEARSANDOLDERWEREELIGIBLE.DESCRIPTIONOFLABORATORYMETHODOLOGYMMAISANALYZEDBYLC-MS/MSASDIBUTYLESTER(MINEVAETAL.).MMAISEXTRACTEDFROMSERUM(75ΜL)ALONGWITHANADDEDINTERNALSTANDARD(D3-MMA)VIALIQUID-LIQUIDEXTRACTIONWITHTERT-BUTYLMETHYLETHER/H+.THEEXTRACTEDACIDISTHENDERIVATIZEDWITHBUTANOLTOFORMADIBUTYLESTER.THEBUTANOLISEVAPORATEDUNDERVACUUMANDTHEDERIVATIZEDSAMPLEISRECONSTITUTEDINACETONITRILE/WATER.THESAMPLEPREPARATIONTAKES~4HFORARUNCONTAINING96SAMPLES(CALIBRATORS,QC’SANDUNKNOWNS).MMAISCHROMATOGRAPHICALLYSEPARATEDFROMOTHERCOMPOUNDSASWELLASTHEISOBARICSUCCINICACID(SAMEMOLECULARMASSASMMA),USINGISOCRATICMOBILEPHASECONDITIONSWITHIN5.9MINANDMEASUREDBYLC-MS/MSUSINGMULTIPLEREACTIONMONITORING.QUANTITATIONISBASEDONPEAKAREARATIOSINTERPOLATEDAGAINSTASIX-POINTAQUEOUSCALIBRATIONCURVE.INCREASEDCONCENTRATIONSOFMMAINPLASMAORSERUMANDEXCESSIVEURINARYEXCRETIONOFMMAAREBELIEVEDTOBEDIRECTMEASURESOFTISSUESTORESOFCOBALAMIN(VITAMINB12)ANDTOBETHEFIRSTINDICATIONOFCOBALAMINDEFICIENCY.THECONCENTRATIONOFMMAINPLASMAORSERUMWASFOUNDTOBEAUSEFULINDICATOROFCOBALAMINDEFICIENCY,ESPECIALLYINPATIENTSWITHFEWORNOHEMATOLOGICALABNORMALITIES,NORMALRESULTSFORTHESCHILLINGTEST,ORNORMALORONLYSLIGHTLYDEPRESSEDSERUMCOBALAMINCONCENTRATIONS.INFOLATEDEFICIENCY,MMAISNORMAL.MMAMAYBEELEVATEDDUETOIMPAIREDRENALFUNCTIONANDASARESULTOFANINBORNERROROFMETABOLISM(METHYLMALONICACIDURIA).REFERTOTHELABORATORYMETHODFILESSECTIONFORADETAILEDDESCRIPTIONOFTHELABORATORYMETHODSUSED.THEREWERENOCHANGESTOTHELABMETHOD,LABEQUIPMENT,ORLABSITEFORTHISCOMPONENTINTHENHANES2013-2014CYCLE.LABORATORYMETHODFILESMETHYLMALONICACID(OCTOBER2018)LABORATORYQUALITYASSURANCEANDMONITORINGSERUMSAMPLESAREPROCESSED,STORED,ANDSHIPPEDTOTHEDIVISIONOFLABORATORYSCIENCES,NATIONALCENTERFORENVIRONMENTALHEALTH,CENTERSFORDISEASECONTROLANDPREVENTION,ATLANTA,GAFORANALYSIS.DETAILEDINSTRUCTIONSONSPECIMENCOLLECTIONANDPROCESSINGAREDISCUSSEDINTHENHANESLABORATORYPROCEDURESMANUAL(LPM).VIALSARESTOREDUNDERAPPROPRIATEFROZEN(–30°C)CONDITIONSUNTILTHEYARESHIPPEDTONATIONALCENTERFORENVIRONMENTALHEALTHFORTESTING.THENHANESQUALITYASSURANCEANDQUALITYCONTROL(QA/QC)PROTOCOLSMEETTHE1988CLINICALLABORATORYIMPROVEMENTACTMANDATES.DETAILEDQA/QCINSTRUCTIONSAREDISCUSSEDINTHENHANESLPM.MOBILEEXAMINATIONCENTERS(MECS)LABORATORYTEAMPERFORMANCEISMONITOREDUSINGSEVERALTECHNIQUES.NCHSANDCONTRACTCONSULTANTSUSEASTRUCTUREDCOMPETENCYASSESSMENTEVALUATIONDURINGVISITSTOEVALUATEBOTHTHEQUALITYOFTHELABORATORYWORKANDTHEQUALITY-CONTROLPROCEDURES.EACHLABORATORYSTAFFMEMBERISOBSERVEDFOREQUIPMENTOPERATION,SPECIMENCOLLECTIONANDPREPARATION;TESTINGPROCEDURESANDCONSTRUCTIVEFEEDBACKAREGIVENTOEACHSTAFFMEMBER.FORMALRETRAININGSESSIONSARECONDUCTEDANNUALLYTOENSURETHATREQUIREDSKILLLEVELSWEREMAINTAINED.ANALYTICALLABORATORIESNHANESUSESSEVERALMETHODSTOMONITORTHEQUALITYOFTHEANALYSESPERFORMEDBYTHECONTRACTLABORATORIES.INTHEMEC,THESEMETHODSINCLUDEPERFORMINGBLINDSPLITSAMPLESCOLLECTEDDURING“DRYRUN”SESSIONS.INADDITION,CONTRACTLABORATORIESRANDOMLYPERFORMREPEATTESTINGON2%OFALLSPECIMENS.NCHSDEVELOPEDANDDISTRIBUTEDAQUALITYCONTROLPROTOCOLFORALLCDCANDCONTRACTLABORATORIES,WHICHOUTLINEDTHEUSEOFWESTGARDRULES(WESTGARD,ETAL.1981)WHENRUNNINGNHANESSPECIMENS.PROGRESSREPORTSCONTAININGANYPROBLEMSENCOUNTEREDDURINGSHIPPINGORRECEIPTOFSPECIMENS,SUMMARYSTATISTICSFOREACHCONTROLPOOL,QCGRAPHS,INSTRUMENTCALIBRATION,REAGENTS,ANDANYSPECIALCONSIDERATIONSARESUBMITTEDTONCHSQUARTERLY.THEREPORTSAREREVIEWEDFORTRENDSORSHIFTSINTHEDATA.THELABORATORIESAREREQUIREDTOEXPLAINANYIDENTIFIEDAREASOFCONCERN.ALLQCPROCEDURESRECOMMENDEDBYTHEMANUFACTURERSWEREFOLLOWED.REPORTEDRESULTSFORALLASSAYSMEETTHEDIVISIONOFLABORATORYSCIENCES’QUALITYCONTROLANDQUALITYASSURANCEPERFORMANCECRITERIAFORACCURACYANDPRECISION,SIMILARTOTHEWESTGARDRULES(CAUDILL,ETAL.2008).DATAPROCESSINGANDEDITINGTHEDATAWEREREVIEWED.INCOMPLETEDATAORIMPROBABLEVALUESWERESENTTOTHEPERFORMINGLABORATORYFORCONFIRMATION.ANALYTICNOTESREFERTOTHE2013-2014LABORATORYDATAOVERVIEWFORGENERALINFORMATIONONNHANESLABORATORYDATA.PLEASEREFERTOTHENHANESANALYTICGUIDELINESANDTHEON-LINENHANESTUTORIALFORDETAILSONTHEUSEOFSAMPLEWEIGHTSANDOTHERANALYTICISSUES.DEMOGRAPHICANDOTHERRELATEDVARIABLESTHEANALYSISOFNHANESLABORATORYDATAMUSTBECONDUCTEDUSINGTHEAPPROPRIATESURVEYDESIGNANDDEMOGRAPHICVARIABLES.THENHANES2013–2014DEMOGRAPHICFILECONTAINSDEMOGRAPHICDATA,HEALTHINDICATORS,ANDOTHERRELATEDINFORMATIONCOLLECTEDDURINGHOUSEHOLDINTERVIEWS;ASWELLASTHESAMPLEDESIGNVARIABLES.THERECOMMENDEDPROCEDUREFORVARIANCEESTIMATIONREQUIRESUSEOFSTRATUMANDPSUVARIABLES(SDMVSTRSANDSDMVPSU,RES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