w w w . r e u m a t o l o g i a . c o m . b r
REVISTA
BRASILEIRA
DE
REUMATOLOGIA
Original
article
High
frequency
of
asymptomatic
hyperparathyroidism
in
patients
with
fibromyalgia:
random
association
or
misdiagnosis?
Juliana
Maria
de
Freitas
Trindade
Costa
a,∗,
Aline
Ranzolin
b,
Cláudio
Antônio
da
Costa
Neto
c,
Claudia
Diniz
Lopes
Marques
b,
Angela
Luzia
Branco
Pinto
Duarte
baPós-Graduac¸ãoemCiênciasdaSaúde,UniversidadeFederaldePernambuco(UFPE),Recife,PE,Brazil
bDepartamentodeReumatologia,HospitaldasClínicas,UniversidadeFederaldePernambuco(UFPE),Recife,PE,Brazil
cFaculdadedeMedicina,UniversidadeFederaldePernambuco(UFPE),Recife,PE,Brazil
a
r
t
i
c
l
e
i
n
f
o
Articlehistory:
Received30October2015 Accepted31January2016 Availableonline8April2016
Keywords: Fibromyalgia Hyperparathyroidism Musculoskeletalpain Hypercalcemia
a
b
s
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r
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c
t
Fibromyalgia (FM) and hyperparathyroidism may present similar symptoms (muscu-loskeletalpain,cognitivedisorders,insomnia,depressionandanxiety),causingdiagnostic confusion.
Objectives: Todeterminethefrequencyofasymptomatichyperparathyroidisminasample ofpatientswithFMandtoevaluatetheassociationoflaboratoryabnormalitiestoclinical symptoms.
Methods:Cross-sectionalstudywith100womenwithFMand57healthywomen (compari-songroup).Parathyroidhormone(PTH),calciumandalbuminlevelswereaccessed,aswell assymptomsintheFMgroup.
Results:InFMgroup,meanserumcalcium(9.6±0.98mg/dL)andPTH(57.06±68.98pg/mL)
valueswereconsiderednormal,althoughPTHlevelshadbeensignificantlyhigherthanin thecomparisongroup(37.12±19.02pg/mL;p=0.001).Hypercalcemichyperparathyroidism wasdiagnosedin6%ofpatientswithFM,and17%ofthesewomenexhibitedonlyhigh lev-elsofPTH,featuringanormocalcemichyperparathyroidism,withhigherfrequenciesthan thoseexpectedfortheirage.Therewasnosignificantassociationbetween hyperparathy-roidismandFMsymptoms,exceptforepigastricpain,whichwasmorefrequentinthegroup ofpatientsconcomitantlywithbothdiseases(p=0.012).
Conclusions: AhighfrequencyofhyperparathyroidismwasnotedinwomenwithFMversus thegeneralpopulation.Normocalcemichyperparathyroidismwasalsomorefrequentin patientswithFM.Longitudinalstudieswithgreaternumberofpatientsareneededtoassess whetherthisisanassociationbychanceonly,iftheincreasedserumlevelsofPTHarepartof FMpathophysiology,orevenifthesewouldnotbecasesofFM,butofhyperparathyroidism. ©2016PublishedbyElsevierEditoraLtda.ThisisanopenaccessarticleundertheCC BY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).
∗ Correspondingauthor.
E-mail:julitrindade@hotmail.com(J.M.Costa).
http://dx.doi.org/10.1016/j.rbre.2016.03.008
Frequência
elevada
de
hiperparatireoidismo
assintomático
em
pacientes
com
fibromialgia:
associac¸ão
ao
acaso
ou
erro
diagnóstico?
Palavras-chave: Fibromialgia Hiperparatireoidismo Dormusculoesquelética Hipercalcemia
r
e
s
u
m
o
A fibromialgia (FM)e ohiperparatireoidismopodem apresentar sintomas semelhantes (doresosteomusculares,distúrbioscognitivos,insônia,depressão eansiedade)e causar confusãodiagnóstica.
Objetivos:Determinarafrequênciadehiperparatireoidismoassintomáticoemumaamostra depacientescomFMeavaliaraassociac¸ãodasalterac¸õeslaboratoriaiscoma sintomatolo-gia.
Metodologia:Estudotransversalcom100mulheresportadorasdeFMe57mulheressaudáveis (grupodecomparac¸ão).Forampesquisadososníveisdeparatormônio(PTH),cálcioe albu-mina,alémdapesquisadesintomasnogrupocomFM.
Resultados: NogrupocomFM,osvaloresmédiosdecálciosérico(9,6±0,98mg/dL)edePTH
(57,06±68,98pg/mL)foramconsideradosnormais,emboraosníveisdePTHtivessemsido
significativamentemaioresdoquenogrupodecomparac¸ão(37,12±19,02pg/mL;p=0,001).
Ohiperparatireoidismohipercalcêmicofoidiagnosticadoem6%daspacientescomFMe17% delasapresentaramapenasPTHelevado,oquecaracterizouohiperparatireoidismo normo-calcêmico,frequênciasmaioresdoqueesperadaparaafaixaetária.Nãohouveassociac¸ão significativaentrehiperparatireoidismoesintomasdaFM,comexcec¸ãodaepigastralgia, quefoimaisfrequentenogrupodepacientescomasduasdoenc¸asconcomitantes(p=0,012). Conclusões:HouvefrequênciaelevadadehiperparatireoidismoemportadorasdeFMquanto àpopulac¸ãogeral.Hiperparatireoidismonormocalcêmicotambémfoimaisfrequenteem pacientescomFM.Estudoslongitudinaisecommaiornúmerodepacientessãonecessários paraavaliarsetrata-seapenasdeumaassociac¸ãoaoacaso,seaselevac¸õesséricasdo PTHfazempartedafisiopatologiadaFMou,ainda,senãoseriamcasosdeFM,esimde hiperparatireoidismo.
©2016PublicadoporElsevierEditoraLtda.Este ´eumartigoOpenAccesssobuma licenc¸aCCBY-NC-ND(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
Primary hyperparathyroidism (PHP), a disease caused by a hyperactive parathyroid and consequent hypercalcemia, is associatedin85–90%ofcases,tothepresenceofsolitarygland adenomas,occurringmostcommonlyinpeopleagedover50 andinwomeninpost-menopause,withaprevalenceof0.78% forthegeneralpopulation.Althoughtheclinicalpresentation isvariable,theasymptomatichypercalcemiaformisthemost common(50–80%).1,2
Fibromyalgia(FM)isoneofthemostcommonrheumatic disorders, affecting approximately 2–8% of the popula-tion, depending on the diagnostic criteria used for its classification.3FMaffectsspeciallyyoungwomen(30–55years
old),4butwiththeuseofnewclassificationcriteria,5the
preva-lence inmen has increased.6 Itsmain feature isa diffuse
andchronicmusculoskeletalpainassociatedwithsymptoms suchasfatigue,sleepdisturbances,morningstiffness,diffuse paresthesias,asubjectivefeelingofedema,cognitive disor-ders,depressionandanxiety.7ThecauseofFMisunknown,
but its development is associated with a disorder of cen-tralnervoussystemregulationwithrespecttopain.Sofar, nosignificantlaboratoryabnormalitieswereidentifiedinFM patients.8
Fatigue, arthralgia, myalgia, sleep disturbances, depres-sion,anxietyandmemoryimpairment–commonsymptoms
inpatientswithFM–arepartofthenonspecificsymptoms in patients with PHP. Asymptomatic PHP is understood as thatcaseinwhichlaboratorychangesareoccurring,with ele-vatedserumlevelsofparathyroidhormone(PTH)andcalcium, without the presence ofthe classic manifestationsofPHP, forinstance,severehypercalcemia,cysticfibrousosteitisand advancedkidneydisease.2Startinginthe70s,withthe
acqui-sitionofnewknowledgeandwithimprovedtechniquesforthe determinationofcalciumandPTH,itwasobservedthatPHP isacommondisorder,andusuallyhasnoseriousorspecific symptoms.2Inaseriesof124casesofPHPevaluatedinthecity
ofRecife(Brazil),47%hadnosymptomsrelatedtothedisease, while25%sufferedfromcysticfibrousosteitis,25%exhibited kidneystoneswithoutboneinvolvement,and2%presented withtypicalneuropsychiatricsyndrome.9
Anotherstudyinvolving4207patientsagedover18in pub-licandprivateendocrinologycentersinRecife(Brazil),found aprevalenceof0.78%(95%CI,0.52to1.04)ofPHP,ofwhich 81.8%wereasymptomatic.10Theratiobetweenwomen:men
was7.2:1,themeanagewas61±16yearsand89.7%ofaffected
femaleswere postmenopausal.Amongthetypical manifes-tationsofPHP,fibrousosteitiswaspresentin6.1%ofcases, nephrolithiasis in 18.2%, and acute neuropsychiatric syn-dromein3%.Theprevalenceofnonspecificsymptomswas 51.5%forfatigueand39.3%formuscleweakness.10
thistotal,50%ofthecasespresentedinaformconsideredas asymptomatic,characterizedbynonspecificsymptomssuch asfatigue,arthralgia,myalgiaandsleepdisorders.11
InpatientswithasymptomaticPHP,ariseinserumlevels ofcalciumisfound,butusuallyonly1mg/dLabovetheupper limitofnormal.Ingeneral,PTHlevelsare1.5–2.0timesgreater thantheupperlimitofnormal,whilethe24-hoururinary cal-ciumtendstoremainunchanged.12
SimilartoFM,hyperparathyroidismalsopredominatesin women, but in a little older age group (post-menopausal females),increasinginprevalencewithage.13,14 Despitethe
similaritybetweensymptomsofFMandasymptomatic hyper-parathyroidism, there are few publications evaluating this association.Thisstudyaimedtodeterminethefrequencyof asymptomatichyperparathyroidisminwomenwithFM, ver-ifytheassociationwithclinicalparameters,andcomparethe resultsofPTHandcalciumfoundinhealthywomen.
Methodology
Patients
Across-sectional,descriptivestudywasconductedbetween August 2011and January 2012, and atotal of 100subjects from the Fibromyalgia Outpatient Clinicof the Rheumato-logyDepartmentoftheHospitaldas Clinicas,Universidade FederaldePernambuco(HC-UFPE)wereincluded.For admis-siontothestudy,theparticipantsshouldbe20–55-yearold womenandmeetthecriteriaforclassificationanddiagnosis ofFM(FMGroup)accordingtotheAmericanCollegeof Rheu-matology(ACR),respectivelyfrom1990and2010.5,15Patients
whorefusedtosigntheconsentformandthosewitha previ-ousdiagnosisofmalignancy,bonemetastases,granulomatous and/orinfectiousdiseases,kidneydisease,hyperthyroidism, hypothyroidism,andacromegaly,inadditiontopatientswho weretakingthiazidediuretics,lithiumsaltsorinreplacement therapywithcalciumandvitaminDwereexcluded.Patients olderthan55yearswerealsoexcludedtoavoidaselection bias,sincePHPismorecommoninthisagegroup.
Apartfromthisgroup,samplesof57healthywomenwere alsocollected,whichformedthecomparisongroup.Matched forage,thecriteriaforinclusionandexclusionofthisgroup werethesametothestudygroup,exceptforthediagnosisof FM.
Clinicalandlaboratoryevaluation
Thedatacollectionprotocolwasalwaysappliedbythesame researcherduringanoutpatientconsultation;and informa-tionnecessaryforthestudywasacquireddirectlywiththe patientandsupplementedbyareviewofhermedicalrecord. Attheendoftheconsultation,bloodwascollectedforserum calcium,albuminandPTH(intactmolecule)determination. Theamountofserumcalciumwasobtainedusingan auto-analyzer(ARCHITECTcSystems,Abbott,USA)whoseadopted referencevaluesrangefrom8.6to10.3mg/dLwitha0.4mg/dL detectionlimit.ForthedosageofPTHa chemoilluminomet-ricassay(IMMULITE2000DPC,LosAngeles,USA)wasused, withreferencevaluesof12–69pg/mLandanalyticalsensitivity
(lowerdetectionlimitwhichcanbedistinguishedfromzero)of 3.0pg/mL.Toserumalbumindosage,bromocresoldye,which specificallybindstoalbuminformingacoloredcomplex,was used. The reference values vary from 3.2 to 5.2g/dL, with adetectionlimitof0.3g/dL(ARCHITECTcSystems,Abbott, USA).Inthepresenceofhypoalbuminemia(values<3.2g/dL), serumcalciumwascorrectedbyfollowingformula16:
Corrected calcium (mg/dL)=Totalcalcium (mg/dL)
+0.8×[4−albumin (g/dL)]
AllsampleswereprocessedintheHC-UFPELaboratory.The studywasapprovedbytheHumanResearchEthicsCommittee intheHealthSciencesCenterofUFPEandallstudysubjects signedaninformed consentpriortohavingtheirdata and bloodsamplescollected.
Definitionofvariables
Thevariablesevaluatedinthestudyweredefinedasfollows:
• Depression:asubjectivefeelingofsadnessdiagnosedbya psychiatristortreatmentwithspecificmedications
• Fatigue:easytiredness,lethargywithoutclinicalsignsto jus-tifyanotherspecificdisease
• Myalgia:musclepainanywhereinthebody
• Arthralgia:non-inflammatory,painfuljointsymptoms
• Emotionallability:depressivesymptoms,anxiety, apprehen-sion,irritabilityornervousness
• Headache:anypainthatoccursinoneormoreskullareas • Non-restorativesleep:feelingtireduponwaking
• Changesinmemory:forgettingsituations,difficulty
concen-tratingonactivities
• Hyperparathyroidism: hypercalcemia (calcium >10.3mg/dL) andelevatedPTHvalues(PTH>69pg/mL)
• Normocalcemic hyperparathyroidism: high PTH (PTH
>69pg/mL)withnormallevelsofserumcalcium.
Statistics
All tests were appliedwitha 95% confidenceinterval.The numericvariablesarerepresentedbymeasuresofcentral ten-dency and dispersion measures. The Kolmogorov–Smirnov normalitytestforquantitativevariableswasused.Toverify theexistenceofanassociation,Fisher’sexacttestfor cate-goricalvariablesandforcomparisonoftwogroups(Studentt [normaldistribution]andMann–Whitney[non-normal distri-bution]test)wasused.Forstatisticalcalculations,thesoftware SPSS(StatisticalPackageforSocialSciences),version17,wasused.
Results
Among the total of 157 women who had their data col-lected, 100 were diagnosed with fibromyalgia and 57 were healthy.Themean(±SD)ageofthepatientswithFMwas42.4 (±8.42)years.AscanbeseeninTable1,themeanvaluesof
Table1–Distributionofmeansforage,serumcalcium
andparathyroidhormoneinfibromyalgiaand
comparisongroups.
Variables Groups p-Value
FM Comparison Mean±SD Mean±SD
Age(years) 42.4±8.42 41.3±9.4 0.443a
Calcium(mg/dL) 9.6±1.0 9.5±0.3 0.612b
PTH(pg/mL) 57.1±69.0 37.1±19.0 0.001b
FM, fibromyalgia; SD, standard deviation; PTH, parathyroid hormone.
a Student’sttest.
b Mann–Whitneytest.
Accordingtothecriteriafordefininghypercalcemic hyper-parathyroidism,itwaspossibletodiagnosethediseaseinsix patients(6%frequency)withFM.Nowomanincomparison group had adiagnosis ofPHP; but this difference was not statisticallysignificant(p=0.087).However,thefrequencyof normocalcemichyperparathyroidisminFMpatientswas17% intheFMgroupversus5.2%incomparisongroup,with statis-ticalsignificance(p=0.045)(Table2).
Theprevalenceofthemostcommonsymptomsofthese two conditions was similar in FM women with and with-outhyperparathyroidism(Table3).Exceptforepigastricpain (p=0.012),noother symptomsweresignificantlyassociated withthepresenceofhyperparathyroidism.
Discussion
In our study, we observed a higher frequency of asymp-tomatic normocalcemic and hypercalcemic hyperparathy-roidism (although notstatistically significant forthe latest manifestation)inpatientswithfibromyalgia,whencompared tothegroupofhealthywomen.Thefrequencyof6%of hyper-parathyroidismfoundinoursampleofpatientswithFMisalso higherthanthatexpectedforthisage-matchedpopulation,as wellasfortheolderpopulation.Inthegeneralpopulation,the prevalenceofhyperparathyroidismforallagesis0.3–0.5%.17,18
AstudyinthecityofRecife,Brazilshowed aprevalenceof 0.78%,and the vast majority(81.8%) were postmenopausal women.10 Although we have not conducted a prevalence
Table2–Frequencyofhyperparathyroidismand
normocalcemichyperparathyroidisminfibromyalgia
andcomparisongroups.
Group p-Valuea
FM(n=100) Comparison(n=57)
n(%) n(%)
HypercalcemicHP 6(6.0) 0(0.0) 0.087
NormocalcemicHP 17(17.0) 3(5.2) 0.045
HP,hyperparathyroidism;FM,fibromyalgia.
a Fisher’sexacttest.
Table3–Frequencyofclinicalsymptomsofpatientsin
fibromyalgiagroup,withandwithout
hyperparathyroidism.
Variables FMgroup p-Valuea
WithHP WithoutHP
n(%) n(%)
Arthralgia 6(100) 85(90.4) 1.000
Myalgia 6(100) 86(91.5) 1.000
Headache 6(100) 80(85.1) 0.591
Depression 2(33.3) 35(37.2) 1.000
Fatigue 5(83.3) 82(87.2) 0.576
Non-restorativesleep 6(100) 84(89.4) 1.000
Memorychange 5(83.3) 66(70.2) 0.669
Nausea/vomiting 3(50) 44(46.8) 1.000
Epigastricpain 6(100) 43(45.5) 0.012
Constipation 0(0) 16(17) 0.586
TMApain 1(16.7) 21(22.3) 1.000
Urinarychanges 0(0) 16(17) 0.586
FM, fibromyalgia; HP, hyperparathyroidism; TMA, temporo-mandibularjoint.
a Fisher’sexacttest.
study with a large number of patients, our data indi-cate ahigherfrequencyofhyperparathyroidisminpatients withFM.
Another phenotype of hyperparathyroidism has been described,consistingofpatientswithnormalserumcalcium andwithPTHelevationintheabsenceofotherknowncause forthishormonalincrease:thenormocalcemic hyperparathy-roidism.Ithasbeenproposedthatthisentitywouldbethefirst phaseofabiphasicdisease,thatlaterwouldbecomeacase of hyperparathyroidism.19 There are few population-based
studiesandtheprevalenceofnormocalcemic hyperparathy-roidismisnotwellestablished,althoughitmaybebetween 0.4 and 3.1%. Normocalcemic hyperparathyroidism should beconsidered aspartofthe diagnosticspectrumof hyper-parathyroidism,andsuchpatientsshouldbemonitoredwith periodiclaboratorydeterminations,withtheaimofanearly detectionofhypercalcemia.19Inoursample,thefrequencyof
normocalcemichyperparathyroidismwasevenhigher(17%) thanthatforhypercalcemichyperparathyroidism(6%),witha statisticaldifferenceinrelationtothepresenceofthis con-dition, when these findings were compared with those of healthy women. However,it would be necessary to obtain serumlevelsofvitaminDtoassessitseffectoncalcium lev-els,whichwasnotpossibleforthisstudy,andthisisitsmain limitation.
Currently,asymptomatichypercalcemiaisconsideredthe mostcommonformofpresentationofPHP.20However,some
studieshaveshownthat,infact,thesepatientsexhibit symp-toms, but becauseofits insidiousand non-specificnature, these are not initially assigned specifically to PHP.12,21 In
a sampleof 229patients withPHP and with surgical indi-cation, seen during a 15-month period, the mostfrequent symptomswere fatigue,asthenia,arthralgia,impaired con-centrationandmemory,anxietyanddepression.22Inviewof
completionoflaboratoryteststodistinguishthesetwoclinical entities.
Althoughthesespecificsymptomsare quite frequentin patientswithhyperparathyroidism,itsetiologyand relation-shiptospecificlaboratory abnormalitiesare stillunknown. Althoughthereisanimprovementinsymptomsafter com-pletionofparathyroidectomy,24 it isunclear whetherthese
symptomsaremediatedbyhypercalcemia,theelevationof PTH, or by some other unknown mechanism.22 The
cor-relation between the normalization of laboratory findings and the resolution of a large number of symptoms after theparathyroidectomysuggests thatthesymptoms associ-atedwith hyperparathyroidism are mediatedbylaboratory biochemical abnormalities.22 Bargren et al. assessed if the
severityofsymptomsisrelatedtoserumcalciumandPTH lev-els.Itwasunexpectedlyobservedthatthemajorityofpatients withboneorjointpain,depression,constipationandrenal cal-culihadserumcalciumlevels<11.2mg/dL,andtherewasno associationofsymptomswithPTHlevels.22Inourstudy,a
rela-tionshipbetweenPTHorcalciumlevelswiththesymptoms wasalsonotfound.
VitaminDdeficiencycanoccurinpatientswithFM,25but
the resultsfoundin the literatureare conflicting.26–28
Cur-rently,itisnotknownwhetherlowserumlevelsofvitamin Dcouldbepartofthepathophysiologyofthegenerationand maintenanceofchronicpain,oraconsequenceofless mobil-ityorofdepressivesymptomsleadingtoalowersunexposure, or also ofhigh rates of adiposity that decrease vitaminD synthesis.29Astudypublishedin2010andcarriedoutinorder
toevaluateserum levels ofvitamin Din patientswith FM versushealthy controls,notedthatthere wasnodifference betweenthetwogroups,butthe levelsofPTHwere signifi-cantlyhigherinpatientswithFM(59.9±17.6pg/L)thaninthe comparisongroup(48.5±17.4pg/L)(p=0.014);inthisstudya relationbetweenPTHlevelsandclinicalsymptomswasnot evaluated.30
An interesting study in 2014 evaluated the presence of FM in hemodialysis patients, finding a frequency of 12.2%.Amongpatientswithand withoutFM,therewasno difference between epidemiological or clinical parameters related to dialysis. Also, there was no significant differ-ence in laboratory parameters betweenthe groups, except for PTH levels, which were higher in patients with FM (p=0.002).31
Ferrariand Russelldetermined theprevalenceofPHPin asampleofpatientswithFM,inpatientswithdiffusepain whodidnotmeetcriteriaforFM,andinagroupofpatients withlocalizedmusculoskeletalpain.Aprevalenceofabout6% ofPHPwasfoundinthesethreegroups–aresultsimilarto ours,andwhichrepresentsanindexhigherthanthatobserved inthegeneralpopulation.Theresultofthis studysuggests thepossibilityofanassociationbetweenPHPanddiffuseor localizedmusculoskeletalpain.32
Severalauthorscitehyperparathyroidismasadifferential diagnosisofmusculoskeletaldiseases,andtherearereportsin theliteratureofcasesofPHPmistakenlydiagnosedasFM.33–35
Inaddition, amongpatientswithsymptomsofFMandPHP whounderwentparathyroidectomy,89%hadimprovementof symptomsofFM,and77%and21%decreasedordiscontinued, respectively,medicationsusedforthispurpose.34
In our study, none ofthe clinical symptoms similar to thetwodiseases,suchasarthralgia,myalgia,non-restorative sleep,memorychangesanddepressionwasdifferentbetween patients with FM with and without hyperparathyroidism, exceptinthecaseofepigastricpain,whichwassignificantly morefrequentinpatientswithincreasedPTHandcalcium. Gastrointestinal manifestationsofhyperparathyroidismare recognizedforseveraldecades,andmayevenbetheinitial iso-latedsymptom.36,37Amongthemostcommonsymptomsone
canobserveconstipation(33%),epigastricpain(30%),nausea (24%) and loss of appetite (15%), with a significant reduc-tionofthesesymptomsafterparathyroidectomy.38Theexact
pathophysiologicalmechanismofthesechangesisnotfully understood,butitisbelievedthatatonyofthe gastrointesti-naltractoccursasaresultofthesustainedstimulationofthe PTHreceptor,whichwouldleadtoconstipationinthecolon andtodyspepsiainthestomach.39Thus,perhapsthe
epigas-tricpainorotherunexplainedandpersistentgastrointestinal symptomsmayconstituteanindicatorforstudiesonPHPin patientswithFM.
The main limitation of this study was the absence of results ofvitaminD dosage inour population. InPHP, the most likelycause ofunusually low concentrations of vita-min D is the increased metabolic clearance induced by 1.25(OH)2D,andpossiblybyPTH,sincethelevelsof25(OH)D return to normal after parathyroidectomy.19 However, the
assessmentofvitaminDwasnotperformedinour compar-isongroup,althoughwefoundsignificantdifferencesinthe frequency ofnormocalcemic hyperparathyroidism between groups.
Ourstudysetouttobeapreliminaryassessmentofan asso-ciation betweenhyperparathyroidism andFM.Accordingto ourresultsandthefewdataintheliterature,apparentlysuch associationexists.Butlongitudinalstudieswithlarger num-bersofpatientsandcontrolsandwithanevaluationofserum levelsofvitaminDareneededtoconfirmwhetherthisisonly achanceassociation,iftheincreasedserumPTHarepartof theFMpathophysiology,oriftheseactuallywouldnotbecases ofFM,butofasymptomaticPHP.
Hyperparathyroidism,despitehavingsymptomssimilarto FM,hasdifferentevolutionandprognosis,whichmayprogress tohighermorbidityandmajorclinicalcomplicationsthatcan bepreventedwithanearlydiagnosis.Althoughmostpatients withasymptomatichyperparathyroidismpresentastable dis-ease,about25%showevidenceofprogressionofthedisease duringfollow-up,indicating thatitisimportanttomonitor patientsnotsubjectedtoparathyroidectomy.24
Thus,basedontheseresultsfound,therequestofa lab-oratoryevaluationofcalciumandPTHserumlevelsmaybe suggestedintheevaluationofpatientswithFMand,incase ofanychange,onemustcontinuetheinvestigationinsearch ofPHP.However,furtherstudieswithgreaterstatisticalpower mayconfirmtheassociationofthetwodiseasesandprovide better subsidies for routine assessment ofthe parathyroid glandsinpatientswithFM.
Conflicts
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