dasar diagnostik laboratorium

8/18/2019 Dasar Diagnostik Laboratorium

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Basic principles of DiagnosticBasic principles of Diagnostic

test (1)test (1)Ideal diagnostic tests – right answers:Ideal diagnostic tests – right answers:(+) results in everyone with the disease and(+) results in everyone with the disease and( - ) results in everyone else( - ) results in everyone else

Clinical prediction rules algorith!Clinical prediction rules algorith!"sual clinical practice:"sual clinical practice:

#he test $e studied in the sa!e way it would $e use #he test $e studied in the sa!e way it would $e usein the clinical settingin the clinical setting

%$servational study and consists of:%$servational study and consists of:&redictor varia$le (test result)&redictor varia$le (test result)%utco!e varia$le (presence ' a$sence of the diseas%utco!e varia$le (presence ' a$sence of the diseas


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ensitivity speci cityensitivity speci city&revalence prior pro$a$ility predictive values&revalence prior pro$a$ility predictive values*i elihood ratios*i elihood ratios

Dichoto!ous scale cuto, points (continuousDichoto!ous scale cuto, points (continuousscale)scale)&ositive (true and false) negative (true and&ositive (true and false) negative (true andfalse)false)

%C (receiver operator characteristic) curve%C (receiver operator characteristic) curve

Basic principles of DiagnosticBasic principles of Diagnostictest (.)test (.)


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Diagnostic testDiagnostic test

general structure : . / . ta$lesgeneral structure : . / . ta$les

#arget disorder #arget disorder&ositive&ositive

(disease)(disease)

#arget disorder #arget disorder0egative0egative(nor!al)(nor!al)

&redictor&redictor #est #est

positivepositive

True positiveTrue positiveTPTPaa

FalseFalsepositivepositive

FPFPbb

&redictor&redictor #est #est

negativenegative

False negativeFalse negativeFNFNcc

TrueTruenegativenegative

TNTNdd

Sensitivity, specificity, predictive values, likelihood ratios, ROC


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EBM Issues on diagnostic testsEBM Issues on diagnostic tests ::

Is this evidence a$out the accuracy of aIs this evidence a$out the accuracy of adiagnostic testdiagnostic test validvalid

Does this valid evidence de!onstrateDoes this valid evidence de!onstrateanan importantimportant a$ility to accuratelya$ility to accuratelydistinguish patients who do and don2tdistinguish patients who do and don2thave a speci c disorderhave a speci c disorderCan ICan I applyapply thisthis validvalid andand importantimportant diagnostic test to a speci c patientdiagnostic test to a speci c patient


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3alidity3alidity


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Does this (valid) evidenceDoes this (valid) evidencede!onstrate ande!onstrate an i!portanti!portant a$ilitya$ilityof this test to accuratelyof this test to accurately

distinguish patients who do anddistinguish patients who do anddon2t have a speci c disorderdon2t have a speci c disorder

SensitivitySensitivity SpecifcitySpecifcity Likeli ood ratiosLikeli ood ratios

I!portance (1)I!portance (1)


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peci typeci tyIf a test is 144 5 speci c it reactsIf a test is 144 5 speci c it reacts

positively only when the clientpositively only when the clientactually has the condition $eingactually has the condition $eingtested6 #he i!portant factors thattested6 #he i!portant factors thatcan e,ect a false positive reactioncan e,ect a false positive reactionsuch as drugs6such as drugs6


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encitivityencitivity #he sencitivity of a test is the degree #he sencitivity of a test is the degree

to which a test detects diseaseto which a test detects diseasewithout yielding a false negativewithout yielding a false negativediagnosis6diagnosis6


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0or!al eference 3alues0or!al eference 3alues0or!al reference values or reference0or!al reference values or reference

values is not as nor!al valuesvalues is not as nor!al values$ecause its la$oratory !ust$ecause its la$oratory !ustdeter!ine what is nor!al for a testdeter!ine what is nor!al for a testperfor!ed in speci c la$oratoryperfor!ed in speci c la$oratory


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7etric 7easur!ents "sed in *a$oratory eports7etric 7easur!ents "sed in *a$oratory eports

8eight8eight9ilogra! ( g)9ilogra! ( g) . . l$. . l$ra! (g)ra! (g) ; 1 l$; 1 l$

7illigra! (!g) > 1'1444 of a g7illigra! (!g) > 1'1444 of a g7icrogra! (7icrogra! ( ?g) > 1'1444 of a !g?g) > 1'1444 of a !g0anogra! (ng) > 1'1444 of a ?g0anogra! (ng) > 1'1444 of a ?g&icogra! (pg) > 1'1444 of a ng&icogra! (pg) > 1'1444 of a ng@e!togra! (fg) > 1'1444 of a pg@e!togra! (fg) > 1'1444 of a pg3olu!e3olu!e*iter (*)*iter (*) > 1444 !l (or 1444 cc)> 1444 !l (or 1444 cc) 164 144 !l or 1'14 of a *Deciliter (d*) > 144 !l or 1'14 of a *7illiliter (!*) > 1 !l or 1'1444 4f a *7illiliter (!*) > 1 !l or 1'1444 4f a *


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"sual #est Done uto!atically $y Cell"sual #est Done uto!atically $y Cell

CountersCounters

ctct e!atocrite!atocrit$$ e!oglo$ine!oglo$in

8BC8BC

8hite $lood cells' leu ocyte8hite $lood cells' leu ocyte

BCBC ed $lood cells' eritrocyteed $lood cells' eritrocyte7C37C3 7ean corpuscular volu!e7ean corpuscular volu!e7C7C 7ean corpuscular he!oglo$in7ean corpuscular he!oglo$in7C C7C C 7ean corpuscular he!oglo$in concentration7ean corpuscular he!oglo$in concentration

D8D8 ed $lood cell distri$ution widthed $lood cell distri$ution width&*# (&lateled counts !ay also $e perfor!ed with so!e&*# (&lateled counts !ay also $e perfor!ed with so!e

counters counters


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I!portance (.)I!portance (.)


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I!portance (=)I!portance (=)

%dds > ratio of two pro$a$ilities%dds > ratio of two pro$a$ilities %dds > p'1-p%dds > p'1-p &ro$a$ility > odds'1+odds&ro$a$ility > odds'1+odds

*i elihood ratio*i elihood ratio (+) :(+) :&rop (+) result in people with the disease&rop (+) result in people with the disease

&rop (+) result in people w'out the disease&rop (+) result in people w'out the disease

&retest %dds / * > &osttest %dds&retest %dds / * > &osttest %dds


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Pretestprobability

Likeli oodratio

Posttestprobability


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#he usefulness of < levels of #he usefulness of < levels ofdiagnostic test resultdiagnostic test result


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ccuracy of the testccuracy of the test #he accuracy of the test #he accuracy of the testdepends on how well thedepends on how well thetest separates the grouptest separates the group$eing tested into those$eing tested into thosewith and without thewith and without thedisease in Auestiondisease in Auestion

ccuracy is !easured $yccuracy is !easured $ythe area under the %Cthe area under the %Ccurve6 n area of 1curve6 n area of 1represents a perfect testrepresents a perfect testan area of 46< representsan area of 46< representsa worthless test ( "C)a worthless test ( "C)

46E4-1644 > eFcellent46E4-1644 > eFcellent( )( )46G4-46E4 > good (B)46G4-46E4 > good (B)46H4-46G4 > fair (C)46H4-46G4 > fair (C)46 4-46H4 > poor (D)46 4-46H4 > poor (D)46 fail (@)46 fail (@)


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pplica$ilitypplica$ility


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Diagnostic tests Diagnostic tests JJ

Is not a$outIs not a$out fnding absolute trutfnd ing absolute trut$ut a$out$ut a$out limiting uncertaintylimitin g uncertaintyesta$lishes $oth the necessity and theesta$lishes $oth the necessity and the

logical $ase for introducing pro$a$ilitieslogical $ase for introducing pro$a$ilitiesprag!atic test-treat!ent thresholds 66prag!atic test-treat!ent thresholds 66

tart thin ing a$outtart thin ing a$outK what you2re going to do with the results ofwhat you2re going to do with the results ofthethe

diagnostic test anddiagnostic test andK whether doing the test will help yourwhether doing the test will help yourpatientspatients

http://c/CATmaker/Diag.pdfhttp://c/CATmaker/Diag.pdfhttp://c/CATmaker/Diag.pdf


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onclusiononclusion

EBM is nothing more than a EBM is nothing more than a framework of systematic use offramework of systematic use ofcurrent valid study resultscurrent valid study results

relevant to our patientsrelevant to our patients


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End result

elf directed life-longlearning attitudefor high Auality patient

care


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T e Principle o! diagnosticT e Principle o! diagnostic

determinedetermine ""#$#$ %namnestic%namnestic&$&$ P ysical 'iagnosticP ysical 'iagnostic

K %uscultation( Palpation%uscultation( PalpationK Percution( Inspection etcPercution( Inspection etc

)$)$ 'iagnostic Tests "'iagnostic Tests "K L%B*+%T*+, L%B*+%T*+, K -.+%, -.+%, K E$/$0E$/$0K EN'*S1*P, EN'*S1*P,


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1linical Laboratory Test1linical Laboratory Test#$#$ 2EM%T*L*0, 2EM%T*L*0,

&$&$ 1LINI1%L 12EMIST+, 1LINI1%L 12EMIST+, )$)$ IM3N* SE+*L*0, IM3N* SE+*L*0, 4$4$ MI/+*BI*L*0,5P%+%SIT*L*0MI/+*BI*L*0,5P%+%SIT*L*0

, ,


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T e use!ul o! LaboratoryT e use!ul o! Laboratory

testtest1616 Deter!ine of diseaseDeter!ine of disease

.6.6 #o elp esta$lished diagnostic #o elp esta$lished diagnostic=6=6 #o evaluation of disease prolong6 #o evaluation of disease prolong6;6;6 7onitoring of therapy67onitoring of therapy6


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2emat ology tests2emat ology tests#$#$ F3LL BL**' 1*3NTF3LL BL**' 1*3NT

+B15E+,T2+*1,TE(+B15E+,T2+*1,TE(6B15LE3/*1,TE( 2B( 21T( M12(6B15LE3/*1,TE( 2B( 21T( M12(M121( M17( PLT( 'IFF 6B1 1*3NTM121( M17( PLT( 'IFF 6B1 1*3NT8PMN( L,MF*1,TE( M*N*1,TE9( ES+$8PMN( L,MF*1,TE( M*N*1,TE9( ES+$

&$ BL**' FILM&$ BL**' FILM)$ 2EM*ST%TI1 TESTS)$ 2EM*ST%TI1 TESTS ""

PT$%PTT(TT(FIB+IN*0ENPT$%PTT(TT(FIB+IN*0EN4$ +ETI13L*1,TE 1*3NT4$ +ETI13L*1,TE 1*3NT:$ B*NE M%++*6 %SPI+%TI*N:$ B*NE M%++*6 %SPI+%TI*N


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Clinical Che!ystri #ests :Clinical Che!ystri #ests :

1616 *iver @unction #ests*iver @unction #ests : # *#' #' %#: # *#' #' %#BI*I "BI0 #%# *BI*I "BI0 #%# * BI*6 DI LC#'I0DI LC# *9 *IBI*6 DI LC#'I0DI LC# *9 *I& % & # L #%# * & %#LI0 *B"7I0 *%B"*I0& % & # L #%# * & %#LI0 *B"7I0 *%B"*I0

.6.6 Dia$etic 7ellitus #ests:Dia$etic 7ellitus #ests: *"9% L (&" &&.*"9% L (&" &&. M 7 % ##) $ 1c M 7 % ##) $ 1c

=6=6 enal @unction #est: " L"7 9 L #I0I0 C*L 0CLenal @unction #est: " L"7 9 L #I0I0 C*L 0CL" L"7 C L #I0I0" L"7 C L #I0I0

;6;6 Cardiac LnNy!e #estsCardiac LnNy!e #ests : C9 C97B 7O% *%BI0: C9 C97B 7O% *%BI0*D )6*D )6


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IM3N*SE+*L*0I TESTSIM3N*SE+*L*0I TESTS#$#$ 7irus In!ection Tests"7irus In!ection Tests"

7I+%L 2EP%TITIS % 8Ig M(ig0 2%797I+%L 2EP%TITIS % 8Ig M(ig0 2%797I+%L 2EP%TITIS B 82bs%g $%nti 2BS( 2Be%g %nti7I+%L 2EP%TITIS B 82bs%g $%nti 2BS( 2Be%g %nti2Be(2B7 'N%92Be(2B7 'N%97I+%L 2EP%TITIS 18%nti 21797I+%L 2EP%TITIS 18%nti 2179Tes 2I7( '2F( T*+12( 'LL$Tes 2I7( '2F( T*+12( 'LL$

&$&$ Bacterical In!ection TestsBacterical In!ection Tests 86I'%L(86I'%L(7'+L(TP2%( M,1*'*T( ET197'+L(TP2%( M,1*'*T( ET19

)$)$ Paracyte In!ection TestsParacyte In!ection Tests 8I1T8I1TPL%SM*'I3M 7I7%-( F%L1IP%+3M ET19PL%SM*'I3M 7I7%-( F%L1IP%+3M ET19

4$4$ 2ormonal Tests2ormonal Tests 8TS2( FT 4( ET198TS2( FT 4( ET19:$:$ Tumor Markers Tests "Tumor Markers Tests " 81E%( %FP( PS%(81E%( %FP( PS%(

1% #&:( ET191% #&:( ET19


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MI/+*BI*L*0,5P%+%SIT*L*0,MI/+*BI*L*0,5P%+%SIT*L*0,TESTS "TESTS "

#$#$ I'ENTIFI1%TI*N '%N IS*L%TI*NI'ENTIFI1%TI*N '%N IS*L%TI*NTESTTEST (C"*#" BI%9I7I ) (C"*#" BI%9I7I )

&$&$ MI1+*S1*P,1 TESTSMI1+*S1*P,1 TESTS ( 7( 7PIL * 0I* L0 0LI L L#C)PIL * 0I* L0 0LI L L#C)

)$)$ P$1$+ TESTP$1$+ TEST4$4$ BL**' FILM T2IN5T2I1/ BL**' FILM T2IN5T2I1/

(7% @%*% O &* 7%DI"7(7% @%*% O &* 7%DI"77%LB L*7I0# L OL # L#C7%LB L*7I0# L OL # L#C

:$:$ IM3N*L*0,5SE+*L*0, IM3N*L*0,5SE+*L*0,


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outine "rinalysis and %theroutine "rinalysis and %ther"rine #ests :"rine #ests :

pppeci c ravitypeci c ravity

&rotein&roteinugarugar

9etones9etonesedi!ent (crystals casts 8BCs BCs )edi!ent (crystals casts 8BCs BCs )

*eu ocyte Lsterase*eu ocyte Lsterase

"rinary &orphyrins"rinary &orphyrinsBiliru$inBiliru$in"ro$ilinogen"ro$ilinogen0itrites0itrites


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