Parte V. Ore 14.30: Tiroide e laboratorio: cosa di fa e cosa si deve fare

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1 Appropriatezza in Medicina di Laboratorio: dalla teoria alla pratica Romolo M Dorizzi, UOC Corelab Laboratorio Unico della Romagna Giovedì 30 aprile 2015-Seconda giornata Parte V. Ore 14.30: Tiroide e laboratorio: cosa di fa e cosa si deve fare Romolo M Dorizzi, Corelab, Pievesestina 1

2 Romolo M Dorizzi, Corelab, Pievesestina 2

3 100 Differentset-points in differentsubjects TSH (mui/l) A B REFERENCE INTERVAL 0.01 ft4 (ng/l) Romolo M Dorizzi, Corelab, Pievesestina 3

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6 Whenthe TSH concentrationiselevated, cliniciansshouldconsiderthatserumtsh levelsmaybecomenormalwithtimein more thanhalfofpatients. In the appropriate clinical setting, a second serum TSH measurement should be madeafterseveralmonths. Romolo M Dorizzi, Corelab, Pievesestina 6

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10 Furthermore, increasedlevels oftsh and low levelsofft4 havebeenassociatedwitha bettersurvivalin elderly subjects(meanage, 85 and 78 yr, respectively). 10 Romolo M Dorizzi, Corelab, Pievesestina 10

11 Thereisevidencethata low activityof thyroidhormonemightbebeneficialin the elderly, whereas sub- clinical hyperthyroidismisa predictorofmortality. It has been demonstrated that subjects withexceptionallongevity(centenarians; medianage, 98 yr) havehigherlevelsof TSH compared with controls. Romolo M Dorizzi, Corelab, Pievesestina 11

12 low thyroidhormonesmight bebeneficialin the elderly, subclinicalhyperthyroidismisa predictorofmortality... higher TSH in subjectswithexceptional longevity(median98 yr) 12 Romolo M Dorizzi, Corelab, Pievesestina 12

13 Thereisa pooragreement betweenreferenceintervals quotedbydifferentlaboratories, evenforthoselaboratories supposedlyquotingintervals suppliedbychirondiagnostics Romolo M Dorizzi, Corelab, Pievesestina 13

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18 The timeofphlebotomyisimportant, (TSH variesthroughout the day, with earlymorning valuesgreaterthanlater ones, and isaccentuatedbysleep deprivation, strenuousexercise, or workingduringthe night or evening shifts). Repeatedmeasurementsvary considerablyovermonths. Romolo M Dorizzi, Corelab, Pievesestina 18

19 Time of phlebotomy The averagedecline between0730 and 0900 and 1030 and 1200 h was26.4% 10 of15with fasting earlymorning TSH between3.0 and 4.5 mu/lhada late morningnonfasting TSH level <3.0 mu/l. Romolo M Dorizzi, Corelab, Pievesestina 19

20 Laboratorians should appreciate that the cutoffs quoted in guidelines often arise from historical data using assays with poorly defined bias that may no longer be available for routine use Romolo M Dorizzi, Corelab, Pievesestina 20

21 Clinicians should appreciate that the TSH cutoffs quoted in guidelines are subject to uncertainty and should be regarded as typical rather than an absolute target figures and thus can be applied with some degree of flexibility. Romolo M Dorizzi, Corelab, Pievesestina 21

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29 I. L esame piùimportante èil TSH. II. Preferire gli anti-tpoagli anti-tg. Una volta diagnosticata una tireopatia autoimmune, non ènecessario monitorare gli anti-tpo. III. Chiedere gli anti-tg, insieme alla Tg, solo nel follow-up del cancro della tiroide. 29 Romolo M Dorizzi, Corelab, Pievesestina 29

30 IV. Chiedere la CT una volta. Nel followupdell MTC inserire CT (+CEA) V. Chiedere FT3 eccezionalmente (l 80% deriva dall FT4). Un aumento dell FT3 con FT4 nei limiti èpraticamente sempre un artefatto di laboratorio. 30 Romolo M Dorizzi, Corelab, Pievesestina 30

31 VI. Monitorare terapia ormonale sostitutiva con solo TSH (target: TSH entro l IR). VII. Monitorare (dopo 2-3 mesi) la terapia ormonale soppressiva con TSH e FT4 (target:tsh < 0.1 mu/l e FT4 entro l IR) e solo con TSH dopo (obiettivo < 0.1 mu/l TSH con FT4 entro l IR). 31 Romolo M Dorizzi, Corelab, Pievesestina 31

32 VIII.Interapia sostitutiva con L-T4 non assumere il farmaco nelle 8 ore prima prelievo. IX.Neiprimi mesi di terapia con farmaci antitiroidei l esame piùutile èl ft4. X.Richiedentee laboratorista devono collaborare strettamente per interpretare alcuni esamitiroidei. 32 Romolo M Dorizzi, Corelab, Pievesestina 32

33 TSH < mu/l >4. 2 ft4 ft4 >17 ng/l ft3 33 Romolo M Dorizzi, Corelab, Pievesestina 33

34 whenever possible diagnostic testing should be deferred until the illness has resolved some thyroid tests are inherently un-interpretable in severely sick patients, or patients receiving multiple medications. Romolo M Dorizzi, Corelab, Pievesestina 34

35 In una popolazione non selezionati di ricoverati in Medicina generale, Geriatria, Psichiatria, il TSH ha una resa bassa di risultati veri positivi e molti risultati falsi-positivi 35 Romolo M Dorizzi, Corelab, Pievesestina 35

36 LR associati ai risultati di TSH stsh(miu/l) Ipotir LR / / >20 11/ Romolo M Dorizzi, Corelab, Pievesestina 36

37 Romolo M Dorizzi, Corelab, Pievesestina 37

38 screening forand treatment ofthyroid dysfunctionin asymptomaticadults doesnotimprovequalityoflife or provideclinicallymeaningful improvementsin bloodpressure, body mass index(bmi), bonemineraldensity, or lipidlevels. Italsodoesnotimprove cognitive function). Romolo M Dorizzi, Corelab, Pievesestina 38

39 Frequentfalse-positive results; the psychologicaleffectsoflabeling; and a largedegreeofoverdiagnosisand overtreatmentofbiochemically definedabnormaltsh levelsthatmay reverttonormal, notprogress, or never resultin healthproblemsevenifthey do progress, particularlyin personswith TSH levelslessthan10 miu/l. Romolo M Dorizzi, Corelab, Pievesestina 39

40 Ifcliniciansofferscreening forthyroid toasymptomaticpersons, theyshould first ensurethatpatientsclearly understandthe uncertainties surroundinganypotentialclinical benefit ofscreening aswellasthe possibilityofharmthischoicemay engender. Romolo M Dorizzi, Corelab, Pievesestina 40

41 Disagreementaboutthe appropriate cut pointsforthe lowerand upper boundariesofnormaltsh levelsin the generalpopulationand in subgroups, suchasolderadults, wherevaluesdifferfromthe overall populationdistribution Romolo M Dorizzi, Corelab, Pievesestina 41

42 In 2006, threebritishprofessional associations(acb, the BTA, and the BTF) jointlyrecommendedagainst routine screening forthyroid dysfunctionin a healthyadult population, althoughthe panel favorsaggressive case findingin women withnonspecificsymptoms Romolo M Dorizzi, Corelab, Pievesestina 42

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