50-Dysfonctionnements thyroidiens

IV#51&DYSFONCTIONNEMENTS&THYROIDIENS&
1!
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Dysfonctionnements&thyroïdiens&
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1. La&thyroïde&:&
"#$%&!'($!)*+(,$!$(,-./0($!%0&'1$!2!*+!3+%$!,'!.-'!$&!.-(%&0&'1$!,$!4!&56$%!,$!
.$**'*$%!7!
8 9$%!:;5/1-.5&$%!<'0!%5(&;1&0%$(&!*$%!=-/>-($%!&;5/-?,0$(($%!@!:A!B!:C!DE!
8 "$**'*$%!"!<'0!%5(&;1&0%$(&!*+!.+*.0&-(0($!
9+!&;5/-)*-3'*0($!@6/1.'/%$'/!,$%!;-/>-($%!:A!B!:CD!%$!&/-'F$!$**$!,+(%!*+!
.-**-?,$E!
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1.1 Les&hormones&thyroïdiennes&:&
:A!-'!&/00-,-&;5/-(0($!@;-/>-($!*+!6*'%!+.&0F$!>+0%!,$>0$!F0$!.-'/&$D!
:C!-'!&1&/+?-,-&;5/-(0($!-'!&;5/-G0($!@6/-8;-/>-($H!6/1.'/%$'/!,$!*+!:AD!
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• Les&protéines&porteuses&:&
8 :;5/-G0($!I0(,0()!J*-3'*0(!@:IJD!KLM!7!:A!B!:C!
8 9#+*3'>0($!NOM!7!:A!B!:C!
8 :;5/-G0($!I0(,0()!P/$Q*3'>0(!@:IPQD!4LM!7!:C!
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1.2 Synthèse&et&régulation&hormonale&
• Libération&et&rétrocontrôle&hormonal&:&
8 9031/+&0-(!,$!:R=!+'!(0F$+'!;56-&;+*+>0<'$!
8 9031/+&0-(!,$!:S=!6+/!*#;56-6;5%$!
8 Q.&0-(!,$!*+!:S=!%'/!*+!&;5/-?,$!7!.+6&+&0-(!,#0-,$!$&!
+.&0F+&0-(!$(T5>+&0<'$E!

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2!
• Mécanisme&de&synthèse&de&T3/T4&:&
8 "+6&+&0-(!,$%!+.0,$%!+>0(1%!$&!,$%!0-,'/$%!%+()'0(%!@&/+(%6-/&!+.&0U!F0+!*$!/1.$6&$'/!2!*+!
:S=D!6+/!*$!&;5/1-.5&$E!
8 S5(&;V%$!,$!*+!&;5/-)*-3'*0($!<'0!%$!,1F$/%$!+F$.!*#0-,$!,+(%!*$!.-**-?,$!
8 Q%%-.0+&0-(!$(!WX:!@W-(-80-,-8&5/-%0($D!$&!YX:!,+(%!*$!.-**-?,$!6'0%!.-(,$(%+&0-(!$(!:A!
$&!:C!!@:AZWX:[YX:!!!:CZYX:[YX:D!
8 \(,-.5&-%$!,'!.-**-?,$!6+/!*$%!.$**'*$%!U-**0.'*+0/$%!$&!U-/>+&0-(!,$!)-'&&$*$&&$%!,$!
.-**-?,$!0(&/+8.5&-6*+%>0<'$%!@6;+)-%->$%!6'0%!6;+)-*5%-%->$%D!!
8 9031/+&0-(!,$!:A!$&!:C!,+(%!*$!&;5/1-.5&$!6+/!;5,/-*5%$!+.0,$!,$!*+!&;5/-)*-3'*0($!,+(%!*$!
6;+)-*5%->$!!
8 9031/+&0-(!%+()'0($![!/$.5.*+)$!,$%!YX:]WX:!!
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• Métabolisme&de&T3/T4&et&élimination&:&
• Q.&0-(!61/06;1/0<'$!,$%!,1%0-,+%$%!;16+&0<'$%!
• :C!!:A!!YX:!!WX:!!:;5/-%0($!
• R$.5.*+)$!,$%!0-,'/$%!X8!*03/$%!$&!.+&+3-*0%>$!,$%!QQ!
• ^I!7!0>6-/&+(.$!,$!*+!,1%0-,+&0-(!,$!:C!@,-(($!:A!$(!U-(.&0-(!,$%!3$%-0(%!;-/>-(+'GD!
• \*0>0(+&0-(!'/0(+0/$!@/$U*$&].-(%-D@"*!0-,'/$%!Z!AO8CO>*]>0(D!$&!,0)$%&0F$!@%%!U-/>$!
)*'.'/-]%'*U-8.-(_')'1D!
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3!
• Iode&dans&l’organisme&:&!
o Différents&isotopes&:&
 X%-&-6$!(+&'/$*!7!XN4K!
 X%-&-6$%!+/&0U0.0$*%!7!!
8 XN4L!!@61/0-,$!Z!`O_-'/%D!
8 XNAN!!@61/0-,$!Z!a_-'/%D!
8 XN4A!!@61/0-,$!Z!A;D!bS.0(&0)/+6;0$!@1*0>!/+60,$D!
o Apports&alimentaires&:&
 "#$%&!*#'(0<'$!%-'/.$!,#0-,$!6-'/!*#-/)+(0%>$!
 P/0(.06+*!/1%$/F-0/!Z!X8!,$%!-.1+(%!
 Q66-/&%!F+/0+3*$%!%$*-(!*$!*0$'@]>$/DH!>-,$!,$!F0$H!;+30&',$%!+*0>!!
!./1&0(0%>$!,$%!Q*6$%!
 Q66-/&%!_-'/(+*0$/%!6-'/!'(!+,'*&$!Z!NOOc)!
!S0!+66-/&%!0-,1!d!4L!c)]_!b=56-&;5/-?,0$!!!
!Q66-/&%!,#0-,$!%5%&1>+&0<'$!,+(%!*$%!/$)0-(%!2!/0%<'$%!,$!.+/$(.$!
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1.3 Effets&physiologiques&de&T3/T4&:&
S$'*$!*+!U/+.&0-(!*03/$!@(-(!*01$D!$%&!30-*-)0<'$>$(&!+.&0F$&
9$%!;-/>-($%!61(V&/$(&!,+(%!*+!.$**'*$!$&!*$!(-5+'!$&!%$!U0G$(&!2!,$%!/1.$6&$'/%!0(&/+('.*1+0/$%!
Q.&0F+&0-(!,$!*+!%5(&;V%$!,$!,0UU1/$(&$%!QR^!0>6*0<'1%!,+(%!*+!%5(&;V%$!,$!6*'%0$'/%!6/-&10($%E!
Q.&0-(!%'/&-'&!>1,01$!6+/!:[email protected](F$/%0-(!:C]:AD&
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• Actions&métaboliques&:&
o Q..1*1/+&0-(!,'!>1&+3-*0%>$!)1(1/+*!$(&/+0(+(&!'($!+')>$(&+&0-(!,$!*#-G5)V($!+'!
(0F$+'!,$!&-'&$%!*$%!.$**'*$%!7!
 Q')>$(&+&0-(!,$!*+!&;$/>-)1(V%$!
 \*1F+&0-(!,$!*+!*06-*5%$!
 Q')>$(&+&0-(!,$!*+!)*5.-)1(-*5%$H!,$!*+!(1-)*'.-)$(V%$H!,$!*+!,1)/+,+&0-(!
,$!*#0(%'*0($!
o S'/!*$!>1&+3-*0%>$!,$!*#$+'!$&!,$%!1*$.&/-*5&$%!7!+')>$(&+&0-(!,$!*+!6$/U'%0-(!
/1(+*$H!,$!*+!U0*&/+&0-(!)*->1/'*+0/$H!,$!*+!/1+3%-/6&0-(!&'3'*+0/$H!6-*5'/0$!

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4!
o S'/!*$!>1&+3-*0%>$!6;-%6;-.+*.0<'$!7!;56$/.+*.0'/0$H!+')>$(&+&0-(!,$!*+!/1%-/6&0-(!
-%%$'%$!
• Effets&cardiovasculaires&:&
o Q')>$(&+&0-(!,'!&/+F+0*!.+/,0+<'$!6-'/!%+&0%U+0/$!+'G!3$%-0(%!+../'%!,$!*#-/)+(0%>$!
o \*1F+&0-(!,'!,130&!$&!,'!/5&;>$!.+/,0+<'$!@&+.;5.+/,0$D!
o Q')>$(&+&0-(!,$!*+!6/$%%0-(!+/&1/0$**$!%5%&-*0<'$!
• Autres&effets&tissulaires&:&
o \UU$&%!%'/!*+!./-0%%+(.$!-%%$'%$!7!6-&$(&0+*0%+&0-(!,$!*+!J=!
o Q.&0-(%!&/-6;0<'$%!+'!(0F$+'!,$!*+!6$+'!
o \UU$&%!%'/!*$!&'3$!,0)$%&0U!7!+..1*1/+&0-(!,'!6/-.$%%'%!,$!*+!,0)$%&0-(!$&!,'!&/+(%0&!
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2. Exploration&de&la&thyroïde&:&
2.1 Clinique&:&
• Examen&local&:&
o X(%6$.&0-(!7!U+.$!$&!6/-U0*E!S0!+(-/>+*$!!;56$/&/-6;0$!,0UU'%$!-'!(-,'*$%!e!
o P+*6+&0-(!7!+%.$(&0-(!2!*+!,1)*'&0&0-(!f!>$%'/$!,'!61/0>V&/$!.$/F0.+*!
o Q'%.'*&+&0-(!7!%-'UU*$!+'!(0F$+'!,$!*+!)*+(,$!%0!I+%$,-g!
• Examen&régional&7!+,1(-6+&;0$%H!%0)($%!,$!.->6/$%%0-(!@,5%6;+)0$H!g$$T0()D!e!
• Examen&général&:!%0)($%!,#;56-!-'!,#;56$/&;5/-?,0$!2!*#0(&$//-)+&-0/$!-'!2!*#$G+>$(!.*0(0<'$!
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2.2 Biologique&:&

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5!
2.2.1 Evaluation&des&réserves&en&iode&:&
Y-%+)$!,$!*#0-,0'/0$!,$%!4C!;!@^*$!7!NOO8AOO!h)]4C;D!!/$U*V&$!*+!<'+(&0&1!,#0-,$!+66-/&1$!6+/!
*#+*0>$(&+&0-(E&
2.2.2 Hormonémie&thyroïdienne&:&
Y-%+)$!,$%!;-/>-($%!*03/$%!7!:C!*03/$![[[!
8 :C!&-&+*$!i!:C!*03/$!
8 :A!&-&+*$!i!:A!*03/$!
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2.2.3 Dosage&de&la&TSH&:&en&1ère&intention&+++&
• Structure&et&synthèse&:&
o S5(&;V%$!6+/!*$%!.$**'*$%!&;5/1-&/-6$%!,$!*#+(&1;56-6;5%$!
o j+>0**$!,$%!;-/>-($%!)*5.-6/-&10<'$%!f!4a!2!AO!kY+!f!6/1%$(.$!,$!.;+0($%!)*5.+($%!$&!,$!
4!%-'%8'(0&1%!@l!$&!mD!
• Régulation&:&
o 9+!:R=!%5(&;1&0%1$!6+/!*#;56-&;+*+>'%!F0$(&!%$!U0G$/!%'/!,$%!/1.$6&$'/%!;56-6;5%+0/$%!
!+%%$>3*+)$!,$%!%-'%8'(0&1%!l!$&!m!%-'%!%-(!+.&0-(!
• Dosage&:&
o :S=!Z!6+/+>V&/$!>+_$'/!,$!*#$G6*-/+&0-(!U-(.&0-(($**$!&;5/-?,0$(($!!6$/>$&!,$!
,0+)(-%&0<'$/!nLM!,$%!6/-3*V>$%!,$!&;5/-?,$E!!
o 9$!,-%+)$!/$6-%$!%'/!'($!>1&;-,$!immunométrique!2!Q.!>-(-.*-(+'G!@>1&;-,$!
SQ^YoX"=DH!&/V%!%$(%03*$!!p!:S=!'*&/+8%$(%03*$!q!@OHON!2!OHO4!>rX]>9D!
o Valeurs&normales&:!NHa!8!A`!6>-*]9!@!OHA!8!`!>r]9!D!
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• TSH&basse!@d!OHN!>r]*D!(l’hypophyse*sécrète*peu*de*TS*)!7!
o s(!,-%$!*$!:C*!6-'/!.-(U0/>$/!*$!,0+)(-%&0.!$&!6/1.0%$/!*#0(&$(%0&1!,$!*#;56$/&;5/-0,0$E!
@>1&;-,$!,0/$.&$!-'!'&0*0%+(&!'(!+(+*-)'$!%&/'.&'/+*H!^!Z!NN84`!6>-*]*DE!
o S0!:C*!+')>$(&1!7!.#$%&!'($!;56$/&;5/-?,0$!U/+(.;$!*(d’origine*thyroïdienne)!
o S0!:C*!3+%%$!-'!(-/>+*$!7!-(!,-%$!*+!:A*!
 S0!:A!+')>$(&1$!$&!6+&0$(&!%5>6&->+&0<'$!7!.#$%&!'($!;56$/&;/5/-0,0$!2!:A!
 S0!:A!(-/>+*$!$&!6+&0$(&!6$'!%5>6&->+&0<'$!7!=56$/&;5/-0,0$!0(U/+.*0(0<'$E!