pem lab h tiroid

7/24/2019 Pem Lab h Tiroid

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Maimun ZA

Clinical Pathology Dept Medical

Faculty Brawijaya Univ


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Structure of thyroid follicle -Euthyroid follicle

Thyroid C-cell

Basal membrane of epithelialcellsApical membrane of epithelialcells

Cuboidal epithelialcells

Basementmembrane

Colloid(glycoprotei

n)

Capillary(Rich blood

supply)


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Physiology

The thyroid follicles secretes tri-iodothyronine(T)andthyro!in(T")synthesis in#ol#es combination ofiodine $ith tyrosine group to form mono and di-iodotyrosine $hich are coupled to form T andT"%

The hormones are stored in follicles bound tothyrogobulin %

&hen hormones released in the blood they arebound to plasma proteins and small amountremain free in the plasma %

The metabolic e'ect of thyroid hormones are due tofree (unbound)T and T"%

*of secreted hormones is T" but Tis the acti#ehormone so+ T"is con#erted to T peripherally%


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Synthesis and libration of T and T" iscontrolled by thyroid stimulatinghormone(TS,)secreted by anterior pituitary

gland%TS, release is in turn controlled by thyrotropin

releasing hormone (TR,)from hypothalamus %Circulating Tand T" e!ert #e feedbac.

mechanism on hypothalamus and anterior

pituitary gland %So+ in hyperthyroidism $here hormone le#el in

blood is high +TS, production is suppressedand #ice #ersa


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Hormone properties T4

T3

Total serum concentrations / 0g1dl %2"0g1dl

3raction of total hormone in

free form (serum)

%4 * % *

3ree (unbound hormone) inserum

42 5 2-24

67 5 2-24

6

Serum half life 8 d %89 d

3raction directly from thethyroid

2 * 4 *

Production rate+ includingperipheral con#ersion

0g1d 4 0g1d

:ntracellular hormone fraction ; 4 * ; 8 *

Characteristics of Circulating T"

and T


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3unctions

ofthyroid hormones


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3unctions of thyroid hormones

Generally, THs:

2% :ncreases metabolic rate% Stimulates increased

consumption of glucose+ fattyacids and other molecules%

4% :ncreases metabolic heat+ by mitochondrial no < acti#ity ATP+

% Stimulates rate of cellularrespiration by=

Production of uncouplingproteins%

:ncrease acti#e transport by>a? @? um s%


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"% >ecessary for normal gro$th recycle synthesis of !IT< ITaccumulate%

!IT< IT$ill not be used for ne$T,s formation

THs%


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::= ,ypothyroidism (my!edema) cont%

Symptoms o Hypothyroidism:- Jecreased metabolic rate%

- Slo$ heart rate < pulse% - Slo$ muscle contractions

- appetite+ $eight gain+ eed to loo. for other pituitarydeMciencies%

:f TS, is h < 3T" < 3T are normal $e call this condition

s$'clinical hypothyroidism


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::= ,ypothyroidismChildren (Cretinism)

,ypothyroidism in childrenT,s%

,ypothyroid from end of 2st

trimester to 7 monthspostnatally+ or in the 2stfe$

years of life%

T3< T4ree! TSH% %dditional Si"ns * Symptoms:

+ Se#ere mental retardation% + Short stature (due to gro$th of

bones+ muscle+ < brain)%


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Thyroid >odule

ery common

7 years old Q "%4* ( Palpation)

2 78* by ultrasound

Autopsy Q 9*

Thyroid Cancer is rare Q " 1 2+

cult thyroid cancer in 7 4" *autopsy


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Thyroid >odule 4

Thyroid nodule #ery common

Thyroid cancer #ery rare butcurable

AIM IS NOT MISS THYROID CANCER


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Thyroid nodule Risk factors

E!posure to radiation as child

3amily history

Lnder 4 years

#er 7 years

O male se!

,ourseness

3i!ed hard nodule Similar ris. for multinodular and

single nodule


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Thyoid >oduleInvesigations

T3Ts

Lltra sound scan

Thyroglobulin and Calcitonin notrecommended ( LS uidelines)

3ine needle Aspration(3>A)


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,ashimotoDs Thyroiditis

Symptoms * Si"ns:

Lsually presents $ith goitre in a patient $ho iseuthyroid or has mild hypothyroidism

Se! distribution= four females to one maleThe process is painless

lder patients may present $ith se#erehypothyroidism $ith only a small+ Mrm atrophicthyroid gland

Transient symptoms of thyroto!icosis can occurduring periods of hashito!icosis (spontaneously

resol#ing hyperthyroidism)


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,ashimotos Thyroiditis

a': >ormal or lo$ thyroid hormone

le#els+ and if lo$+ TS, is ele#ated

,igh Tg Ab and1or TP Ab titres 3>A b! re#eals a large inMltrationof lymphocytes PKLS ,urthle cells

-omplications:

Permanent hypothyroidism (occursin 2-29* of young pts)

Rarely+ thyroid lymphoma


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Thyroid 3unction Tests

TS, Thyro!ine (T") (free 1 total)

Ttriiodothyronine (T) (free 1 total)

Thyroid Antibodies= Autoimmune

thyroid disease is detected bycirculating antibodies against TP andTg%

:maging

Thyroid Lltrasound scan

Thyroid :sotope Scan


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uidelines The diagnosis of primary hypothyroism

reuires the measurement of both TS, andT" Patients $ith type-2 diabetes should ha#e a

chec. of thyroid function included in their

annual re#ie$% Patients $ith type-4 diabetes

should ha#e their function chec.ed atdiagnosis but routine annual thyroid functiontesting is not recommended

Patients stabilised on long term thyro!ine

treatment should ha#e TS, chec.ed annually


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uidelines The thyroid status of hypothyroid patients

should be chec.ed $ith TS, ? T" during eachtrimester:deally the follo$ing seuence of T3T should be

performed in the hypothyroid $omen duringpregnancy

Before conception At time of diagnosis of pregnancy At antenatal boo.ing At least once in 4ndand rdtrimester Again after deli#ery at 4 " $ee.s post partum

>e$ly diagnosed hypothyroid $ill need testinge#ery " 7 $ee.s until stable


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Thyroid Antibodies

Thyroid Pero!idase(thyroid microsomal)

100% in Hashimato thyroiditis

87% with graves disease

Thyroglobulin Antibody 76% of Graves Disease

Thyroid receptor antibody

Normally resent in 1! "18 % offemale o#lation

6 TS,


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6easure TS,

Ele#ated

>ormal

6easure unbound T" Pituitary disease

suspected

>ormal yes>oKo$

6ild

hypothyroidism

Primaryhypothyroidi

sm

>o

furthertest

6easure

unboundT"

TP Ab(?)or

symptomatic

TP Ab(-)

or no

symptoms

TPAb(?)

TPAb (-)

>o

furthertest

>ormal

Ko$

Rule out drug e'ects+sic. euthyroid

syndrome+ then

E#aluate anterior

Rule out othercauses of

hypothyroidismAutoimmune

hypothyroidismT" treatment

Annual follo$up T" treatment

Application of TS, e!amination


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I-%s. /01

ioassayary insensitiityInconinient

RI%sSensitiity 1m$-ross reaction . 15Hypothyroid

IR%sSensitiity

1/ + 2// x RI%s Hypo 6e$thyroid

HyperthyroidTSH /0/7 + /011m$

8$thyroid/04 9 40/

Hypothyroid4 m

!etection

Imm$noassayI : 7 9 ; m

II: /01 9 /02

Imm$noassayIII:/0/1 9 /0/2

I: /0//1 9 /0//2

I II

Application of TS, e!amination

Autoimmune Thyroiditis (A:T)


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AutoimmuneThyroiditis (A:T)

Anti Tg

Cytoplasma

follicular

Complemen

t acti#ation

(-)

Anti TP

29 .Ja+ microsomal

Thyroid pero!idase

enNyme

Pos correlation= anti TP

< PPTJ

Complement acti#ation

(?)

AntiTS,-R

,yperthyroid

,ypothyroid :n J

Ab bispeciMc= Ab TP more freuent < higher than ant

nly anti TP (?)= rare

Anti TP < anti Tg in J= not established (discussion)

Routine detection Ab thyroid= only anti TP


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Ab

bispeciMcPPTJ= 27 *

> population= 2%"

*

Pre#alence of anti

TPPPTJ (post partum

thyroiditis)= 27 *

ra#eDs disease= "%7 *

,asimoto thyroiditis= "%9 *Anti TP < A:T

Clinical rele#ancy= not clearly

Correlation $ith acti#e clinical

disease

Strong correlation $ith ris. of


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Anti TP for predict PPTJ

ariation of sensiti#ity < speciMcity

Jepend on $hen anti TP e!amined

PPTJ (-) $hen anti TP (-)

Screening anti TP in early pregnancy


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Serum Tg E!amination

>ot distinguished= PPTJ < J

:nterference= serum anti Tg

(reaction of anti Tg ? anti Tg

antibody in immunoassay .it)+

e!amination simultaneously Tg? anti Tg


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pem lab h tiroid

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