Download SURGICAL DISEASES OF THE THYROID GLAND

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 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 gland
Biosynthesis 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
4
Regulation of TH synthesis/secretion
Normal circulatory concentrations
– T4 4.5-11 g/dL
– T3 60-180 ng/dL (~100-fold less than T4)
6
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
7
Thyroid 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
8
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
9
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
10
Thyroid Hormone is Critical for Normal
Bone Growth
– T3 also may participate in osteoblast
differentiation and proliferation, and chondrocyte
maturation leading to bone ossification
11
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
12
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
13
Evaluation of patients with Thyroid gland disorder
THREE MAIN CATEGORIES
• HYPOFUNCTION
• HYPERFUNCTION
• ENLARGMENTS/GOITER
– DIFFUSE ENLARGMENT
– NODULAR ENLARGMENT
Thyroid Disease Spectrum
15
Clinical 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
Thyroid 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(99mTcsodium 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
HYPERTHYROIDISM
•
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

I.
II.
III.
IV.
V.
VI.
SIGNS
sinus Tachycardia
Hot,moist palms
Exosphthalmos
Lid lag
Agitation
Thyroid goitre
 SYMPTOMS
I. Tiredness
II. Emotional lability
III. Heat intolerance
IV. Wt.loss
V. Excessive appetite
VI. palpitations
19
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
Graves’ 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
21
Graves’ Disease
22
Graves’ Disease
• Manage graves by 1)anti-thyroid drugs
and,2)radioactive iodine ablation<CI in preg.>
3)surgery; subtotal-thyroidectomy
23
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
Thyroid 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
Hyperthyroidism
DIFFUSE GLAND ENLARGMENT
PRETIBIAL MYXEDEMA
GRAVE’S OPHTHALMOPATHY
Hyperthyroidism
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)
HYPOTHYROIDISM
• 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 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
THYROID 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
THYROID 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
THYROID CANCER
• MANAGEMENT
• SURGERY
• LOBECTOMY + ISTHMUSECTOMY
• TOTAL THYROIDECTOMY
• INDICATED NECK DISSECTION
• ADJUVANT TREATMENT
• POSTOPERAIVE RADIOACTIVE IODINE
TREATMENT
• EXTERNAL BEAM RADIATION
• CHEMOTHERAPY (emerging)
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
Types of thyroid surgeries
•
•
•
•
SUBTOTAL-THYROIDECTOMY
TOTAL-THYROIDECTOMY(bilateral lobectomy)
ISTHMUSECTOMY
NEAR-TOTAL THYROIDECTOMY(total thyroid
lobectomy on affected side with conservation of 12grm of thyroid on contralateral side to preserve
blood flow to parathyroids
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Complications of thyroid surgery
 HAEMORRHAGE
 NERVE DAMAGE
 HYPOTHYROIDISM
 HYPOPARATHYROIDISM
 Wound infection(abscess must be drained)
 Respiratory obstruction(kinking of trachea,laryngeal
oedema,trauma during intubation)
Technique of thyroidectomy
Technique of thyroidectomy
Technique of thyroidectomy
Technique of thyroidectomy
Technique of thyroidectomy
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