Top Banner
THE THYROID THE THYROID GLAND GLAND HYPOTHYROIDISM HYPOTHYROIDISM
34

THE THYROID GLAND

Jan 01, 2016

Download

Documents

gay-moses

THE THYROID GLAND. HYPOTHYROIDISM. DIRECT METHODS Circulating levels of total hormones total thyroxine (TT 4 ) total triiodothyronine (TT 3 ) protein bound iodine (PBI) Circulating levels of free hormones free thyroxine (fT 4 ) free triiodothyronine (fT 3 ) - PowerPoint PPT Presentation
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: THE  THYROID  GLAND

THE THYROID THE THYROID GLANDGLAND

HYPOTHYROIDISMHYPOTHYROIDISM

Page 2: THE  THYROID  GLAND

MEASUREMENT OF THYROID HORMONESMEASUREMENT OF THYROID HORMONES

DIRECT METHODSDIRECT METHODS Circulating levels of total Circulating levels of total

hormoneshormones total thyroxine (TTtotal thyroxine (TT44))

total triiodothyronine (TTtotal triiodothyronine (TT33)) protein bound iodine (PBI)protein bound iodine (PBI)

Circulating levels of free Circulating levels of free hormoneshormones

free thyroxine (fTfree thyroxine (fT44))

free triiodothyronine (fTfree triiodothyronine (fT33))

Thyroid hormone binding Thyroid hormone binding proteinsproteins

Thyroxine binding globulin (TBG)Thyroxine binding globulin (TBG)

INDIRECT METHODSINDIRECT METHODS Thyroid hormone binding Thyroid hormone binding

teststests resin uptake of resin uptake of 125125I-TI-T33

Free thyroxine index (FTI)Free thyroxine index (FTI)

FTI=FTI=TT4 4 x patient x patient 125125I-TI-T3 3 resin uptakeresin uptake

Control Control 125125I-TI-T33 resin uptake resin uptake

Page 3: THE  THYROID  GLAND

OTHER TESTS OF THYROID FUNCTIONOTHER TESTS OF THYROID FUNCTION

Dynamic tests of thyroid Dynamic tests of thyroid

activityactivity Thyroid uptake of Thyroid uptake of 123123I or I or 131131I I

(and scan)(and scan)

Thyroid uptake of Thyroid uptake of 9999mTcmTc T3 suppression testT3 suppression test

TSH stmulationTSH stmulation test test

Tests of the thyroid-Tests of the thyroid-

pituitary axispituitary axis Basal serum TSHBasal serum TSH

Serum TSH response to Serum TSH response to

exogenous TRHexogenous TRH

impaired response - hyperthyroid

exaggerated response - hypothyroid

normal response - euthyroid

Page 4: THE  THYROID  GLAND

HYPOTHYROIDISMHYPOTHYROIDISM

Hypothyroidism is a disease caused by a Hypothyroidism is a disease caused by a

level of thyroid hormone insufficient for level of thyroid hormone insufficient for

normal body function.normal body function.

It affects every cell of human body.It affects every cell of human body.

An enlarged thyroid gland is the An enlarged thyroid gland is the

abnormality present in most cases.abnormality present in most cases.

Page 5: THE  THYROID  GLAND

HYPOTHYROIDISMHYPOTHYROIDISM

Causes of hypothyroidismCauses of hypothyroidism

PRIMARYPRIMARY

/thyroid gland//thyroid gland/

SECONDARYSECONDARY

/pituitary//pituitary/

TERTIARYTERTIARY

/hypothalamus//hypothalamus/

Page 6: THE  THYROID  GLAND

Primary hypothyroidismPrimary hypothyroidism

CONGENITALCONGENITAL AthyreosisAthyreosis

Ectopic thyroidEctopic thyroid DyshormonogenesisDyshormonogenesis

Iodide deficiencyIodide deficiency Antithyroid immunity Antithyroid immunity

(transient due to illness)(transient due to illness)

ACQUIREDACQUIRED Iodine deficiencyIodine deficiency

AutoimmunityAutoimmunity Post-radioactive iodine Post-radioactive iodine

therapytherapy Post-thyroidectomyPost-thyroidectomy Antithyroid drugs Antithyroid drugs

(e.g. Carbimazole)(e.g. Carbimazole) Iodine excessIodine excess

Subacute thyroiditisSubacute thyroiditis Thyroid irradiationThyroid irradiation

Page 7: THE  THYROID  GLAND

Secondary hypothyroidismSecondary hypothyroidism pituitary tumourspituitary tumours

pituitary granulomas (e.g. sarcoid) or injurypituitary granulomas (e.g. sarcoid) or injury „„empty sella” syndromeempty sella” syndrome

Tertiary hypothyroidismTertiary hypothyroidism hypothalamic disorders (e.g. craniopharyngioma)hypothalamic disorders (e.g. craniopharyngioma)

Isolated TRH deficiencyIsolated TRH deficiency

Page 8: THE  THYROID  GLAND

CAUSES OF HYPOTHYROIDISMCAUSES OF HYPOTHYROIDISM

Iodine deficiency is the most common Iodine deficiency is the most common cause of goitre and bordeline cause of goitre and bordeline hypothyroidism worldwide.hypothyroidism worldwide.

In noniodine-deficient areas In noniodine-deficient areas autoimmunity is the common cause of autoimmunity is the common cause of

hypothyroidismhypothyroidism

Page 9: THE  THYROID  GLAND

EFFECTS OF IODINEEFFECTS OF IODINE

Goitre, rarely hypothyroidismGoitre, rarely hypothyroidismDEFICIENCYDEFICIENCY

Temporary inhibition Temporary inhibition of thyroid hormone synthesisof thyroid hormone synthesis

(Wolff-Chaikoff effect)(Wolff-Chaikoff effect)Induction of thyrotoxicosisInduction of thyrotoxicosis

(Jod-Basedow phenomenon)(Jod-Basedow phenomenon)

EXCESS,EXCESS,ACUTEACUTE

Goitre, hypothyroidismGoitre, hypothyroidismEXCESS,EXCESS,CHRONICCHRONIC

Page 10: THE  THYROID  GLAND

IODINE DEFICIENCYIODINE DEFICIENCY

REDUCTION OF DIETARY IODINE INTAKEREDUCTION OF DIETARY IODINE INTAKE

thyroid hormone production thyroid hormone production

(preferential secretion of T(preferential secretion of T33 rather than T rather than T44))

compensatory compensatory TSH secretion TSH secretion

Page 11: THE  THYROID  GLAND

IODINE DEFICIENCYIODINE DEFICIENCY

MODERATE MODERATE Urinary iodide Urinary iodide

excretion:excretion:25 -5025 -50μμ/g creatinine/g creatinine

Prevalence of Prevalence of goitre:goitre:

20 -50%20 -50%

Hypothyroidism:Hypothyroidism:rarelyrarely

SEVERESEVERE Urinary iodide Urinary iodide

excretion:excretion:

<25<25μμ/g creatinine/g creatinine

Prevalence of Prevalence of goitre:goitre:>50%>50%

Hypothyroidism:Hypothyroidism:frequentlyfrequently

Page 12: THE  THYROID  GLAND

EXCESS OF IODINEEXCESS OF IODINE

Acute increase in intracellular iodine Acute increase in intracellular iodine concentrationsconcentrations

Temporal inhibition of thyroid hormone Temporal inhibition of thyroid hormone

synthesis and release synthesis and release (Wolff-Chaikoff effect)(Wolff-Chaikoff effect)

Decrease in intracellular iodine concentrationDecrease in intracellular iodine concentration

(escape from Wolff-Chaikoff effect)(escape from Wolff-Chaikoff effect)

Page 13: THE  THYROID  GLAND

EXCESS OF IODINEEXCESS OF IODINE

Introduction of iodine therapy in areas of Introduction of iodine therapy in areas of iodine deficiencyiodine deficiency

Increase in the frequency of Increase in the frequency of

thyrotoxicosisthyrotoxicosis(Jod-Basedow phenomenon)(Jod-Basedow phenomenon)

unmasking thyroid autonomy unmasking thyroid autonomy (previously protected by iodine deficiency)(previously protected by iodine deficiency)

Page 14: THE  THYROID  GLAND

EXCESS OF IODINEEXCESS OF IODINEProlonged iodine ingestion in patients with Prolonged iodine ingestion in patients with

autoimmune thyroiditis autoimmune thyroiditis (Hashimoto’s (Hashimoto’s disease)disease) and in fetal and neonatal period and in fetal and neonatal period

(maternal ingestion of excess iodine)(maternal ingestion of excess iodine)

Permanent hypothyroidism Permanent hypothyroidism

and goitre formationand goitre formation

No excape from Wolff-Chaikoff effectNo excape from Wolff-Chaikoff effect

Page 15: THE  THYROID  GLAND

CLINICAL PICTURE OF CLINICAL PICTURE OF

HYPOTHYROIDISM DEPENDS ON TIME HYPOTHYROIDISM DEPENDS ON TIME

OF THE ONSET OF DISEASEOF THE ONSET OF DISEASE

Page 16: THE  THYROID  GLAND

CONGENITAL HYPOTHYROIDISMCONGENITAL HYPOTHYROIDISM

The prevalence:The prevalence:

1 : ~4,000 live births1 : ~4,000 live births Usually no signs at birthUsually no signs at birth

Untreated congenital hypothyroidismUntreated congenital hypothyroidism

Non-reversible retardation of physical Non-reversible retardation of physical

and mental developmentand mental development

Page 17: THE  THYROID  GLAND

Clinical features of congenital Clinical features of congenital hypothyroidismhypothyroidism

Typical faceTypical face MacroglossiaMacroglossia

Enlarged posterior Enlarged posterior fontanelle (>0.5 cm) fontanelle (>0.5 cm) NN

HypotoniaHypotonia HypoactivityHypoactivity Mottled skinMottled skin

Cold extremitiesCold extremities Dry skinDry skin

Umbilical hernia (>0.5cm) Umbilical hernia (>0.5cm) NN

Delayed passage of Delayed passage of meconium meconium NN

ConstipationConstipation Feeding problemsFeeding problems Prolonged icterus Prolonged icterus NN Hoarse, grunting cryHoarse, grunting cry

GoiterGoiter Placidity, lethargyPlacidity, lethargy

Growth retardation and Growth retardation and immature body proportionsimmature body proportions Mental retardationMental retardation

N – symptoms only observed in the neonatal periodN – symptoms only observed in the neonatal period

All signs are facultative and frequently are not seen in All signs are facultative and frequently are not seen in the neonatal phase.the neonatal phase.

Page 18: THE  THYROID  GLAND

CONGENITAL HYPOTHYROIDISMCONGENITAL HYPOTHYROIDISM

May be detected biochemically by screening May be detected biochemically by screening all neonates 3 – 5 days after birth.all neonates 3 – 5 days after birth.

T4 screening TSH screening

False positive

False negative

PrematurityPrematurity

Low TBGLow TBG

Laboratory errorLaboratory errorLaboratory errorLaboratory error

Ectopic thyroidEctopic thyroid

Laboratory errorLaboratory error

HypopituitarismHypopituitarism

Laboratory errorLaboratory error

Page 19: THE  THYROID  GLAND

ACQUIRED HYPOTHYROIDISMACQUIRED HYPOTHYROIDISM

In noniodine-deficient areasIn noniodine-deficient areas

primary hypothyroidism primary hypothyroidism

women : men = 10 : 1women : men = 10 : 1

The prevalence in women of all ages:The prevalence in women of all ages:

2 - 4%2 - 4%

(one-third of this cases (one-third of this cases iatrogenic hypothyroidism) iatrogenic hypothyroidism)

Page 20: THE  THYROID  GLAND

ACQUIRED HYPOTHYROIDISMACQUIRED HYPOTHYROIDISM

CLINICAL FEATURES IN HYPOTHYROIDISMCLINICAL FEATURES IN HYPOTHYROIDISM

The symptoms of hypothyroidism are The symptoms of hypothyroidism are

nonspecific and may be attributed by both nonspecific and may be attributed by both

patient and doctor to ageing, the onset patient and doctor to ageing, the onset

usually being insidious.usually being insidious.

Page 21: THE  THYROID  GLAND

Symptoms of hypothyroidismSymptoms of hypothyroidismUSUALUSUAL

LethargyLethargy Increased sleepIncreased sleep

ConstipationConstipation Mild weight gain Mild weight gain Cold intoleranceCold intolerance Facial puffinessFacial puffiness

Dry skinDry skin Hair lossHair loss

HoarsensessHoarsensess Abnormal mensesAbnormal menses AcroparaesthesiaeAcroparaesthesiae

Snoring Snoring

RARERARE

DeafnessDeafness

PsychosisPsychosis

Cerebellar disturbanceCerebellar disturbance

MyotoniaMyotonia

Page 22: THE  THYROID  GLAND

SIGNS OF HYPOTHYROIDISMSIGNS OF HYPOTHYROIDISM

Change in appearance Change in appearance (e.g. face puffy and (e.g. face puffy and

pale)pale) Periorbital oedemaPeriorbital oedema

Dry, flaking, cool, pasty Dry, flaking, cool, pasty skinskin

Diffuse hair lossDiffuse hair loss BradycardiaBradycardia

Signs of median nerve Signs of median nerve compressioncompression

(carpal tunnel syndrome)(carpal tunnel syndrome)

Effusions in body Effusions in body

cavities cavities

(e.g. ascites, pericardial (e.g. ascites, pericardial

effusion)effusion)

Delayed relaxation of Delayed relaxation of

reflexesreflexes

Croaky voiceCroaky voice

GoitreGoitre

Rarely stupor or comaRarely stupor or coma

Page 23: THE  THYROID  GLAND

MYXOEDEMAMYXOEDEMAMyxoedema is a severe form of hypothyroidism Myxoedema is a severe form of hypothyroidism

causing complete exhaustion of all bodily causing complete exhaustion of all bodily functions.functions.

All the organs are infiltrated with All the organs are infiltrated with mucopolysaccharides that interfere with mucopolysaccharides that interfere with

proper cell metabolism.proper cell metabolism.Myxoedema patients have all the symptoms and Myxoedema patients have all the symptoms and

signs described for hypothyroidism, as well as signs described for hypothyroidism, as well as low brain center reserve, low cardiac reserve, low brain center reserve, low cardiac reserve, low respiratory reserve, low adrenal reserve, low respiratory reserve, low adrenal reserve,

and low thermoregulatory reserve. In addition, and low thermoregulatory reserve. In addition, they may show hyponatremia, hypercapnia, they may show hyponatremia, hypercapnia,

hypoxia, and anemia.hypoxia, and anemia.

Page 24: THE  THYROID  GLAND

HYPOTHYROIDISM- HYPOTHYROIDISM- DIAGNOSTIC PROCEDURESDIAGNOSTIC PROCEDURES

TSH levelTSH level

(second or third generation assays = the lower (second or third generation assays = the lower detection limit: 0.05-0.005 -0.002 mU/l)detection limit: 0.05-0.005 -0.002 mU/l)

FTFT44 level level

(the measurement of T(the measurement of T33 is not a good is not a good

diagnostic test for hypothyroidism)diagnostic test for hypothyroidism) TSH response to exogenous TRHTSH response to exogenous TRH

(secondary and tertiary hypothyroidism; (secondary and tertiary hypothyroidism; subclinical hypothyroidism)subclinical hypothyroidism)

Page 25: THE  THYROID  GLAND

Hypothyroidism- summary of Hypothyroidism- summary of diagnostic testsdiagnostic tests

PrimaryPrimary

HypothyroidismHypothyroidism

Secondary Secondary

HypothyroidismHypothyroidism

Tertiary Tertiary

HypothyroidismHypothyroidism

Non-thyroid Non-thyroid

illnessillness

Basal Basal

TSHTSH

raisedraised

low or normallow or normal

low, normallow, normal

or elevatedor elevated

normal or lownormal or low

TT44

lowlow

lowlow

lowlow

lowlow

TRHTRHresponseresponse

exaggeratedexaggerated

reducedreducedor absentor absent

sluggish sluggish or delayedor delayed

normal or lownormal or low

Page 26: THE  THYROID  GLAND

Subclinical hypothyroidismSubclinical hypothyroidism(diminished thyroid reserve)(diminished thyroid reserve)

Serum TSerum T44 : normal (lower half of the normal range) : normal (lower half of the normal range)

Serum TSerum T33: normal or sometimes even slightly elevated: normal or sometimes even slightly elevated

Basal TSHBasal TSH: slightly raised : slightly raised

TSH/TRHTSH/TRH: exaggerated: exaggerated

Definition: „subclinical” Definition: „subclinical” no symptoms and signs (?) no symptoms and signs (?)

Patients with subclinical hypothyroidism are at Patients with subclinical hypothyroidism are at increased risk for coronary heart diseaseincreased risk for coronary heart disease

HOWEVERHOWEVER

Page 27: THE  THYROID  GLAND

IMAGING STUDIESIMAGING STUDIES

Rapidly growing large goiter; Rapidly growing large goiter; Goiter with a dominant nodule;Goiter with a dominant nodule;

Hashimoto’s diseaseHashimoto’s disease

ultrasonography examination and fine ultrasonography examination and fine

needle aspiration biopsyneedle aspiration biopsy

Page 28: THE  THYROID  GLAND

IMAGING STUDIESIMAGING STUDIES

Cardiac function shoud be assessed Cardiac function shoud be assessed

before treatment is started.before treatment is started.

The presence of other associated The presence of other associated

autoimmune endocrinopathies must be autoimmune endocrinopathies must be

ascertained.ascertained.

Page 29: THE  THYROID  GLAND

HYPOTHYROIDISM –HYPOTHYROIDISM –TREATMENTTREATMENT

Hypothyroidismis treated with replacement Hypothyroidismis treated with replacement TT44 therapy therapy (sodium L-thyroxine)(sodium L-thyroxine)

Replacement doses usually start at 50 Replacement doses usually start at 50 μμg/d g/d being increased in a stepwise fashion at being increased in a stepwise fashion at monthly intervals to 100 - 150 monthly intervals to 100 - 150 μμg/d as the g/d as the

response is assessed clinically and response is assessed clinically and biochemically.biochemically.

Page 30: THE  THYROID  GLAND

HYPOTHYROIDISM –HYPOTHYROIDISM –TREATMENTTREATMENT

There is considerable variation in patient There is considerable variation in patient

response to Tresponse to T44 because of differential thyroid because of differential thyroid

hormone receptor isoform tissue hormone receptor isoform tissue

concentration.concentration.

Page 31: THE  THYROID  GLAND

HYPOTHYROIDISM –HYPOTHYROIDISM –TREATMENTTREATMENT

During TDuring T44 therapy: therapy:

Serum TSerum T33 concentration must be in the concentration must be in the

normal range, as should that of TSHnormal range, as should that of TSH

Serum TSerum T44 may exceed the upper limit of may exceed the upper limit of

normal.normal.

Page 32: THE  THYROID  GLAND

HYPOTHYROIDISM –HYPOTHYROIDISM –TREATMENTTREATMENT

During TDuring T44 therapy: therapy:

Clinically satisfactory response:Clinically satisfactory response:

normal pulse rate normal pulse rate

and complete resolution of presenting symptoms and complete resolution of presenting symptoms

and signs.and signs.

Occasionally cardiac symptoms such as palpitations Occasionally cardiac symptoms such as palpitations

may occur; in this case a may occur; in this case a ββ-adrenergic blocker drug -adrenergic blocker drug

is indicatedis indicated..

Page 33: THE  THYROID  GLAND

HYPOTHYROIDISM –HYPOTHYROIDISM –TREATMENTTREATMENT

In patients with ischemic heart disease:In patients with ischemic heart disease:

Replacement therapy should be introduced Replacement therapy should be introduced

cautiously, with started doses of 25cautiously, with started doses of 25μμg/d; g/d;

increments should also be smallincrements should also be small..

Page 34: THE  THYROID  GLAND

Protocol for the management of Protocol for the management of myxoedema comamyxoedema coma

Take blood for diagnostic tests: TTake blood for diagnostic tests: T44, ,

TSH and plasma cortisolTSH and plasma cortisol

Give 300 Give 300 μμg Tg T44 i.v. and repeat i.v. and repeat

approximately 100 approximately 100 μμg q.d; give via g q.d; give via

nasogastric tube if i.v. preparation nasogastric tube if i.v. preparation

is unaviableis unaviable

Treat hypothermia with gradual Treat hypothermia with gradual

rewarming using blanketsrewarming using blankets

Give i.m. hydrocortisone 75 mg Give i.m. hydrocortisone 75 mg

immediately and repeat 25-50 mg 8-immediately and repeat 25-50 mg 8-

hourlyhourly

Give TGive T33 20 20 μμg i.v., i.m. or by g i.v., i.m. or by

nasogastric tube 12-hourly, if nasogastric tube 12-hourly, if

possible possible

Treat any heart failure with Treat any heart failure with

diureticsdiuretics

Correct any electrolyte Correct any electrolyte

disturbancesdisturbances

Carefully exclude or treat Carefully exclude or treat

infectioninfection

Use sedative drugs and fluids Use sedative drugs and fluids

sparingly sparingly

Measure serum TMeasure serum T44, T, T33 and TSH and TSH

frequentlyfrequently