THYROID GLAND MJ Noon 2014-57. Anatomy of the thyroid gland Light brown, firm organ 15 – 20 gms in weight Two lateral lobes connected by an isthmus 4.

THYROID GLANDTHYROID GLAND

MJ Noon 2014-57MJ Noon 2014-57

Anatomy of the thyroid glandAnatomy of the thyroid gland

•Light brown, firm organ•15 – 20 gms in weight•Two lateral lobes connected by an isthmus•4 x 2 cm in dimension; 20 – 40 mm thickness•Pyramidal lobe present in 80% of normal persons; usually left of midline•Four parathyroid glands closely related•Recurrent laryngeal nerves on both sides

•Light brown, firm organ•15 – 20 gms in weight•Two lateral lobes connected by an isthmus•4 x 2 cm in dimension; 20 – 40 mm thickness•Pyramidal lobe present in 80% of normal persons; usually left of midline•Four parathyroid glands closely related•Recurrent laryngeal nerves on both sides

Anatomy of the thyroid glandAnatomy of the thyroid gland

Biosynthesis of T4 and T3Biosynthesis of T4 and T3

The process includes• Dietary iodine (I) ingestion• Active transport and uptake of iodide (I-) by

thyroid gland• Oxidation of I- and iodination of

thyroglobulin (Tg) tyrosine residues • Coupling of iodotyrosine residues (MIT and

DIT) to form T4 and T3

• Proteolysis of Tg with release of T4 and T3

into the circulation

The process includes• Dietary iodine (I) ingestion• Active transport and uptake of iodide (I-) by

thyroid gland• Oxidation of I- and iodination of

thyroglobulin (Tg) tyrosine residues • Coupling of iodotyrosine residues (MIT and

DIT) to form T4 and T3

• Proteolysis of Tg with release of T4 and T3

into the circulation

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Regulation of TH synthesis/secretionRegulation of TH synthesis/secretion

Normal circulatory concentrationsNormal circulatory concentrations

– T4 4.5-11 g/dL

– T3 60-180 ng/dL (~100-fold less than T4)

– T4 4.5-11 g/dL

– T3 60-180 ng/dL (~100-fold less than T4)

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Carriers for Circulating Thyroid Hormones

Carriers for Circulating Thyroid Hormones

• More than 99% of circulating T4 and T3 is bound to plasma carrier proteins– Thyroxine-binding globulin (TBG), binds

about 75%– Transthyretin (TTR), also called thyroxine-

binding prealbumin (TBPA), binds about 10%-15%

– Albumin binds about 7%– High-density lipoproteins (HDL), binds

about 3%

• Carrier proteins can be affected by physiologic changes, drugs, and disease

• More than 99% of circulating T4 and T3 is bound to plasma carrier proteins– Thyroxine-binding globulin (TBG), binds

about 75%– Transthyretin (TTR), also called thyroxine-

binding prealbumin (TBPA), binds about 10%-15%

– Albumin binds about 7%– High-density lipoproteins (HDL), binds

about 3%

• Carrier proteins can be affected by physiologic changes, drugs, and disease

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Thyroid Hormone Plays a Major Role in Growth and DevelopmentThyroid Hormone Plays a Major

Role in Growth and Development

• Thyroid hormone initiates or sustains differentiation and growth– Stimulates formation of proteins– Is essential for normal brain development

• Essential for childhood growth– Untreated congenital hypothyroidism or

chronic hypothyroidism during childhood can result in incomplete development and mental retardation

• Thyroid hormone initiates or sustains differentiation and growth– Stimulates formation of proteins– Is essential for normal brain development

• Essential for childhood growth– Untreated congenital hypothyroidism or

chronic hypothyroidism during childhood can result in incomplete development and mental retardation

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Thyroid Hormones and the Central Nervous System (CNS)

Thyroid Hormones and the Central Nervous System (CNS)

• Thyroid hormones are essential for neural development and maturation and function of the CNS

• Decreased thyroid hormone concentrations may lead to alterations in cognitive function– Patients with hypothyroidism may

develop impairment of attention, slowed motor function, and poor memory

– Thyroid-replacement therapy may improve cognitive function when hypothyroidism is present

• Thyroid hormones are essential for neural development and maturation and function of the CNS

• Decreased thyroid hormone concentrations may lead to alterations in cognitive function– Patients with hypothyroidism may

develop impairment of attention, slowed motor function, and poor memory

– Thyroid-replacement therapy may improve cognitive function when hypothyroidism is present 9

Thyroid Hormone Influences the Female Reproductive System

Thyroid Hormone Influences the Female Reproductive System

• Normal thyroid hormone function is important for reproductive function

– Hypothyroidism may be associated with menstrual disorders, infertility, risk of miscarriage, and other complications of pregnancy

• Normal thyroid hormone function is important for reproductive function

– Hypothyroidism may be associated with menstrual disorders, infertility, risk of miscarriage, and other complications of pregnancy

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Thyroid Hormone is Critical for Normal Bone Growth

Thyroid Hormone is Critical for Normal Bone Growth

– T3 also may participate in osteoblast

differentiation and proliferation, and chondrocyte maturation leading to bone ossification

– T3 also may participate in osteoblast

differentiation and proliferation, and chondrocyte maturation leading to bone ossification

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Thyroid Hormone Regulates Mitochondrial Activity

Thyroid Hormone Regulates Mitochondrial Activity

• T3 is considered the major regulator of mitochondrial activity

– A potent T3-dependent transcription

factor of the mitochondrial genome induces early stimulation of transcription and increases transcription factor (TFA) expression

– T3 stimulates oxygen consumption by the

mitochondria

• T3 is considered the major regulator of mitochondrial activity

– A potent T3-dependent transcription

factor of the mitochondrial genome induces early stimulation of transcription and increases transcription factor (TFA) expression

– T3 stimulates oxygen consumption by the

mitochondria

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Thyroid Hormones Stimulate Metabolic Activities in Most

Tissues

Thyroid Hormones Stimulate Metabolic Activities in Most

Tissues

• Thyroid hormones (specifically T3)

regulate rate of overall body

metabolism– T3 increases basal metabolic rate

• Calorigenic effects– T3 increases oxygen consumption by most

peripheral tissues

– Increases body heat production

• Thyroid hormones (specifically T3)

regulate rate of overall body

metabolism– T3 increases basal metabolic rate

• Calorigenic effects– T3 increases oxygen consumption by most

peripheral tissues

– Increases body heat production

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Evaluation of patients with Thyroid gland disorder

Evaluation of patients with Thyroid gland disorder

THREE MAIN CATEGORIES• HYPOFUNCTION• HYPERFUNCTION• ENLARGMENTS/GOITER– DIFFUSE ENLARGMENT– NODULAR ENLARGMENT

THREE MAIN CATEGORIES• HYPOFUNCTION• HYPERFUNCTION• ENLARGMENTS/GOITER– DIFFUSE ENLARGMENT– NODULAR ENLARGMENT

Thyroid Disease SpectrumThyroid Disease Spectrum

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Clinical evaluationClinical evaluation• HISTORY AND PHYSICAL EXAMINATION• Clinical manifestations:

– HYPERFUNCTION• Weight loss, irritability, heat intolerance, thinning of hair,

palpitations, tachycardia– HYPOFUNCTION

• Weight gain, lethargy, coarse hair, cold intolerance, thick skin, slowed muscle reflex, constipation, slow mentation

– GOITER• Anterior neck mass that moves on deglutition is thyroid

gland in origin unless proven otherwise; enlarged thyroid gland

• Physical Examination:– Accurate description of the thyroid gland and mass– Appreciate presence or absence of associated cervical

lymphadenopathy

• HISTORY AND PHYSICAL EXAMINATION• Clinical manifestations:

– HYPERFUNCTION• Weight loss, irritability, heat intolerance, thinning of hair,

palpitations, tachycardia– HYPOFUNCTION

• Weight gain, lethargy, coarse hair, cold intolerance, thick skin, slowed muscle reflex, constipation, slow mentation

– GOITER• Anterior neck mass that moves on deglutition is thyroid

gland in origin unless proven otherwise; enlarged thyroid gland

• Physical Examination:– Accurate description of the thyroid gland and mass– Appreciate presence or absence of associated cervical

lymphadenopathy

Thyroid Function TestsThyroid Function Tests• T3 AND T4 LEVELS

• Serum TSH and TRH

• Free and bound ratio

• Plain films; X-Rays(chest/thoracic inlet;clinical evidence of tracheal deviation,compression,retrosternal extension)

• Ultrasonography(solid/cystic)or radioisotope scanning(99mTc-sodium pertechnate) for differentiating between

A. HOT nodules (actively functioning)

B. COLD nodules (non-functioning)

C. COOL (normaly functioning) MRI and CT (EXTENT OF GOITRE) FNAC(nature of thyroid nodules) Thyroid antibodies

• T3 AND T4 LEVELS

• Serum TSH and TRH

• Free and bound ratio

• Plain films; X-Rays(chest/thoracic inlet;clinical evidence of tracheal deviation,compression,retrosternal extension)

• Ultrasonography(solid/cystic)or radioisotope scanning(99mTc-sodium pertechnate) for differentiating between

A. HOT nodules (actively functioning)

B. COLD nodules (non-functioning)

C. COOL (normaly functioning) MRI and CT (EXTENT OF GOITRE) FNAC(nature of thyroid nodules) Thyroid antibodies

HYPERTHYROIDISMHYPERTHYROIDISM• Clinical syndrome of excess

thyroid hormone in the circulation

• Two dominant types or causes:

– Grave’s disease

– Toxic multinodular or solitary nodular goiter (Plummer’s disease)

• Can be PRIMARY (increased Thyroid hormone independent of TSH) or SECONDARY (increased in hormone due to increased TSH)

• Clinical syndrome of excess thyroid hormone in the circulation

• Two dominant types or causes:

– Grave’s disease

– Toxic multinodular or solitary nodular goiter (Plummer’s disease)

• Can be PRIMARY (increased Thyroid hormone independent of TSH) or SECONDARY (increased in hormone due to increased TSH)

HYPERTHYROIDISM/THYROTOXICOSIS

HYPERTHYROIDISM/THYROTOXICOSIS

SIGNSI. sinus

TachycardiaII. Hot,moist

palmsIII.ExosphthalmosIV.Lid lagV. AgitationVI.Thyroid goitre

SIGNSI. sinus

TachycardiaII. Hot,moist

palmsIII.ExosphthalmosIV.Lid lagV. AgitationVI.Thyroid goitre

SYMPTOMSI. TirednessII.Emotional labilityIII.Heat intoleranceIV.Wt.lossV.Excessive

appetiteVI.palpitations

SYMPTOMSI. TirednessII.Emotional labilityIII.Heat intoleranceIV.Wt.lossV.Excessive

appetiteVI.palpitations

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Graves’ disease (diffuse toxic goiter)Graves’ disease (diffuse toxic goiter)• Most common cause of primary hyperthyrodism• Female dominant autoimmune disease• Inciting events; infection, steroid withdrawal,

postpartum, iodide excess• Anti-TSH receptor antibodies(IgG),type2

hypersensitivity• TSI can cross placenta so neonatal thyrotoxicosis

can occur• LABS;

A. Raised T3,T4

B. Low TSH

C. TSH producing response to TRH is absent because of atrophy of pituitary TSH producing cells

• Most common cause of primary hyperthyrodism• Female dominant autoimmune disease• Inciting events; infection, steroid withdrawal,

postpartum, iodide excess• Anti-TSH receptor antibodies(IgG),type2

hypersensitivity• TSI can cross placenta so neonatal thyrotoxicosis

can occur• LABS;

A. Raised T3,T4

B. Low TSH

C. TSH producing response to TRH is absent because of atrophy of pituitary TSH producing cells

Graves’ DiseaseGraves’ Disease• CLINACAL FEATURES; INFILTRATIVE OPHTHALMOPATHY Proptosis of eye(volume of retro-orbital connective

tissue is increased; inflamation,GAGS,fatty infiltration;orbital fibroblasts have TSH receptor and become targets of antibody attack)

Pretibial myxedema( GAGS in dermis) Thyroid acropachy;

a) Digital swelling

b) Finger clubbing

• Cardiac problems;CHF,AF• Apathy,muscle weakness• thyromegaly

• CLINACAL FEATURES; INFILTRATIVE OPHTHALMOPATHY Proptosis of eye(volume of retro-orbital connective

tissue is increased; inflamation,GAGS,fatty infiltration;orbital fibroblasts have TSH receptor and become targets of antibody attack)

Pretibial myxedema( GAGS in dermis) Thyroid acropachy;

a) Digital swelling

b) Finger clubbing

• Cardiac problems;CHF,AF• Apathy,muscle weakness• thyromegaly

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Graves’ DiseaseGraves’ Disease

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Graves’ DiseaseGraves’ Disease

• Manage graves by 1)anti-thyroid drugs and,2)radioactive iodine ablation<CI in preg.> 3)surgery; subtotal-thyroidectomy

• Manage graves by 1)anti-thyroid drugs and,2)radioactive iodine ablation<CI in preg.> 3)surgery; subtotal-thyroidectomy

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Multinodular Toxic Goiter (Plummer’s disease)Multinodular Toxic Goiter (Plummer’s disease)

• One or more thyroid nodules trapping and organifying more iodine and increase secretion of hormone independent of TSH control; autonomously functioning nodule/s

• No exophthalmos or pretibial myxoedema (Milder with no extrathyroidal manifestations)• Demonstrate increased uptake or radioactive iodine I131

localized to the nodule/s • Hot nodules on scan• Poor response to radioactive iodine treatment; surgery

is the choice of management

• One or more thyroid nodules trapping and organifying more iodine and increase secretion of hormone independent of TSH control; autonomously functioning nodule/s

• No exophthalmos or pretibial myxoedema (Milder with no extrathyroidal manifestations)• Demonstrate increased uptake or radioactive iodine I131

localized to the nodule/s • Hot nodules on scan• Poor response to radioactive iodine treatment; surgery

is the choice of management

Thyroid StormThyroid Storm• Rare but life-threatening complication of hyperthyroidism• Induced by thyroidal or non-thyroidal surgery; can be induced by

infection or other forms of stress (eg. Labor & delivery, pulmonary infection, after RAI treatment)

• Signs and symptoms of severe thyrotoxicosis– Hyperpyrexia, severe tachycardia, irritability, vomiting,

diarrhea, and proximal muscle weakness; cause of death due to high cardiac output

• Management:– Prevention is the best management– Immediate control of tachycardia, mechanical cooling, oxygen

and volume resuscitation– Steroids– Intravenous beta-blockers (propranolol)– Anti-thyroid drugs and Iodine solution– Peritoneal dialysis in extreme cases

• Rare but life-threatening complication of hyperthyroidism• Induced by thyroidal or non-thyroidal surgery; can be induced by

infection or other forms of stress (eg. Labor & delivery, pulmonary infection, after RAI treatment)

• Signs and symptoms of severe thyrotoxicosis– Hyperpyrexia, severe tachycardia, irritability, vomiting,

diarrhea, and proximal muscle weakness; cause of death due to high cardiac output

• Management:– Prevention is the best management– Immediate control of tachycardia, mechanical cooling, oxygen

and volume resuscitation– Steroids– Intravenous beta-blockers (propranolol)– Anti-thyroid drugs and Iodine solution– Peritoneal dialysis in extreme cases

HyperthyroidismHyperthyroidism

PRETIBIAL MYXEDEMAPRETIBIAL MYXEDEMA

DIFFUSE GLAND ENLARGMENTDIFFUSE GLAND ENLARGMENT

GRAVE’S OPHTHALMOPATHYGRAVE’S OPHTHALMOPATHY

HyperthyroidismHyperthyroidismDIAGNOSIS• History and Physical Examination• Thyroid Function tests• Radioactive iodine thyroid scan• Ultrasonography

MANAGEMENT• MEDICAL MANAGEMENT

– Anti-thyroid drugs (methimazole, PTU)

– Beta-blockers (propranolol)– Radioactive Iodine

• SURGERY– Subtotal thyroidectomy; Lobectomy

• RADIOACTIVE IODINE TREATMENT– Diffuse = 7 – 9 mCi– Nodular = 12 – 15 mCi

DIAGNOSIS• History and Physical Examination• Thyroid Function tests• Radioactive iodine thyroid scan• Ultrasonography

MANAGEMENT• MEDICAL MANAGEMENT

– Anti-thyroid drugs (methimazole, PTU)

– Beta-blockers (propranolol)– Radioactive Iodine

• SURGERY– Subtotal thyroidectomy; Lobectomy

• RADIOACTIVE IODINE TREATMENT– Diffuse = 7 – 9 mCi– Nodular = 12 – 15 mCi

RADIOACTIVE IODINE SCAN(Iodine 131)

RADIOACTIVE IODINE SCAN(Iodine 131)

HYPOTHYROIDISMHYPOTHYROIDISM

• Syndrome of deficient circulating levels of thyroid hormone

• Cretinism in neonates – neurological impairment and mental retardation

• Clinical manifestations:– Myxedema (severe

form)– Bradycardia &

cardiomegaly• Laboratory:

– Decreased T3 and T4; Elevated TSH

• Management:– Thyroxine replacement

• Syndrome of deficient circulating levels of thyroid hormone

• Cretinism in neonates – neurological impairment and mental retardation

• Clinical manifestations:– Myxedema (severe

form)– Bradycardia &

cardiomegaly• Laboratory:

– Decreased T3 and T4; Elevated TSH

• Management:– Thyroxine replacement

THYROID CANCERTHYROID CANCER

• The most common endocrine malignancy that requires surgery

• Included in the top 10 sites of malignancy for both sexes in the Philippines

• Generally slow-growing and indolent malignancy

• AGE – considered the most important prognostic factor

• Certain types are also aggressive malignancy and potentially fatal disease

• The most common endocrine malignancy that requires surgery

• Included in the top 10 sites of malignancy for both sexes in the Philippines

• Generally slow-growing and indolent malignancy

• AGE – considered the most important prognostic factor

• Certain types are also aggressive malignancy and potentially fatal disease

THYROID CANCERTHYROID CANCER• MAJOR HISTOLOGIC TYPES

• PAPILLARY THYROID CANCER– Most common (70%); well-differentiated– Slow-growing; lymphatic spread– Good prognosis• FOLLICULAR THYROID CANCER– Well-differentiated; 2nd most common

(10%)– More aggressive; vascular invasion and

spread• MIXED PAPILLARY-FOLLICULAR THYROID

CANCER– Behaves and managed as papillary

carcinoma• HURTHLE-CELL TUMOR– 5% incidence; intermediate differentiation– Behaves like follicular carcinoma but

spread by lymphatics

• MAJOR HISTOLOGIC TYPES• PAPILLARY THYROID CANCER

– Most common (70%); well-differentiated– Slow-growing; lymphatic spread– Good prognosis• FOLLICULAR THYROID CANCER– Well-differentiated; 2nd most common

(10%)– More aggressive; vascular invasion and

spread• MIXED PAPILLARY-FOLLICULAR THYROID

CANCER– Behaves and managed as papillary

carcinoma• HURTHLE-CELL TUMOR– 5% incidence; intermediate differentiation– Behaves like follicular carcinoma but

spread by lymphatics

THYROID CANCERTHYROID CANCER• MAJOR HISTOLOGIC TYPES

• LYMPHOMA (5%)– Usually in females; history of previous

hashimoto’s– Surgery for compressive symptoms– Chemo and radiation sensitive• MEDULLARY THYROID CANCER– Aggressive; calcitonin producing tumor– 90% sporadic; 10% part of the MEN II

syndrome– Does not uptake I131

– Poor prognosis; undifferentiated carcinoma• ANAPLASTIC THYROID CANCER– Worst prognosis; very aggressive– 30% developed from well-differentiated

cancer (degeneration)– Chemo and radiation treatment– Palliatve surgery

• MAJOR HISTOLOGIC TYPES• LYMPHOMA (5%)

– Usually in females; history of previous hashimoto’s

– Surgery for compressive symptoms– Chemo and radiation sensitive• MEDULLARY THYROID CANCER– Aggressive; calcitonin producing tumor– 90% sporadic; 10% part of the MEN II

syndrome– Does not uptake I131

– Poor prognosis; undifferentiated carcinoma• ANAPLASTIC THYROID CANCER– Worst prognosis; very aggressive– 30% developed from well-differentiated

cancer (degeneration)– Chemo and radiation treatment– Palliatve surgery

• MANAGEMENT• SURGERY• LOBECTOMY + ISTHMUSECTOMY• TOTAL THYROIDECTOMY• INDICATED NECK DISSECTION

• ADJUVANT TREATMENT• POSTOPERAIVE RADIOACTIVE IODINE

TREATMENT• EXTERNAL BEAM RADIATION• CHEMOTHERAPY (emerging)

• MANAGEMENT• SURGERY• LOBECTOMY + ISTHMUSECTOMY• TOTAL THYROIDECTOMY• INDICATED NECK DISSECTION

• ADJUVANT TREATMENT• POSTOPERAIVE RADIOACTIVE IODINE

TREATMENT• EXTERNAL BEAM RADIATION• CHEMOTHERAPY (emerging)

THYROID CANCERTHYROID CANCER

INDICATIONS FOR THE PERFORMANCE OF THYROID

SURGERY

INDICATIONS FOR THE PERFORMANCE OF THYROID

SURGERY

• Thyroid enlargement (Goiter) causing compression symptoms (dysphagia, dyspnea)• Certain types of Hyperthyroidism• Thyroid Nodule/s or Thyroid Cancer• Cosmetic indication

• Thyroid enlargement (Goiter) causing compression symptoms (dysphagia, dyspnea)• Certain types of Hyperthyroidism• Thyroid Nodule/s or Thyroid Cancer• Cosmetic indication

Types of thyroid surgeriesTypes of thyroid surgeries

• SUBTOTAL-THYROIDECTOMY• TOTAL-THYROIDECTOMY(bilateral

lobectomy)• ISTHMUSECTOMY• NEAR-TOTAL THYROIDECTOMY(total thyroid

lobectomy on affected side with conservation of 1-2grm of thyroid on contralateral side to preserve blood flow to parathyroids

• SUBTOTAL-THYROIDECTOMY• TOTAL-THYROIDECTOMY(bilateral

lobectomy)• ISTHMUSECTOMY• NEAR-TOTAL THYROIDECTOMY(total thyroid

lobectomy on affected side with conservation of 1-2grm of thyroid on contralateral side to preserve blood flow to parathyroids

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HAEMORRHAGE NERVE DAMAGE HYPOTHYROIDISM HYPOPARATHYROIDISM Wound infection(abscess must be drained) Respiratory obstruction(kinking of trachea,laryngeal

oedema,trauma during intubation)

HAEMORRHAGE NERVE DAMAGE HYPOTHYROIDISM HYPOPARATHYROIDISM Wound infection(abscess must be drained) Respiratory obstruction(kinking of trachea,laryngeal

oedema,trauma during intubation)

Complications of thyroid surgeryComplications of thyroid surgery

Technique of thyroidectomyTechnique of thyroidectomy

Technique of thyroidectomyTechnique of thyroidectomy

Technique of thyroidectomyTechnique of thyroidectomy

Technique of thyroidectomyTechnique of thyroidectomy

Technique of thyroidectomyTechnique of thyroidectomy

THANK YOUTHANK YOU