Thyroid case

1. Disease of the Thyroid
 BY: T. B Muleta(MD)

2. Fig 19.6a Anatomy and Histological Organization of the Thyroid Gland

3. Thyroid Gland
 The thyroid (Greek thyreos, shield, plus eidos, form)
consists of two lobes connected by an isthmus
 It is located anterior to the trachea between the cricoid
cartilage and the suprasternal notch
 The normal thyroid is 12–20 g in size, highly vascular, and
soft in consistency
 The recurrent laryngeal nerves traverse the lateral borders
of the thyroid gland and must be identified during thyroid
surgery to avoid injury and vocal cord paralysis.

4. Cont…
 The thyroid gland develops from the floor of the primitive
pharynx during the third week of gestation
 The developing gland migrates along the thyroglossal duct
to reach its final location in the neck
 This feature accounts for the rare ectopic location of
thyroid tissue at the base of the tongue (lingual thyroid) as
well as the occurrence of thyroglossal duct cysts along this
developmental tract

5. Cont…
 The thyroid gland produces two related hormones,
thyroxine (T4 ) and triiodothyronine (T3 )
 Acting through thyroid hormone receptors (TR) α and β
 These hormones play a critical role in cell differentiation
and organogenesis during development and help maintain
thermogenic and metabolic homeostasis in the adult
 Thyroid hormone synthesis begins at about 11 weeks’
gestation.

6. Cont…
 Four parathyroid glands, which produce parathyroid
hormone are located posterior to each pole of the thyroid
 Neural crest derivatives from the ultimobranchial body give
rise to thyroid medullary C cells that produce calcitonin, a
calcium-lowering hormone
 The C cells are interspersed throughout the thyroid gland
 Calcitonin plays a minimal role in calcium homeostasis in
humans
 But the C cells are important because of their involvement
in medullary thyroid cancer

7. Regulation of Thyroid Hormone Synthesis

8. Follicles: the Functional Units of the Thyroid Gland

10. Iodine transporter
1. Sodium-iodine c0-symporter(NIS)
 Iodide uptake is mediated by NIS which is expressed at the basolateral
membrane of thyroid follicular cells
 Is most highly expressed in the thyroid gland, but low levels are
present in the salivary glands, lactating breast, and placenta
 The selective expression of NIS in the thyroid allows isotopic scanning,
treatment of hyperthyroidism, and ablation of thyroid cancer with
radioisotopes of iodine, without significant effects on other organs
 Mutation of the NIS gene is a rare cause of congenital hypothyroidism,
underscoring its importance in thyroid hormone synthesis.

11. Cont…
2. pendrin
 Is located on the apical surface of thyroid cells and
mediates iodine efflux into the lumen
 Mutation of the pendrin gene causes Pendred syndrome
 Is a disorder characterized by defective organification of
iodine, goiter, and sensorineural deafness

12. Cont…
 Disorders of thyroid hormone synthesis are rare causes of
congenital hypothyroidism
 The vast majority of these disorders are due to recessive
mutations in TPO or Tg, but defects have also been
identified in the TSH-R, NIS, pendrin, hydrogen peroxide
generation, and dehalogenase, as well as genes involved in
thyroid gland development

13. Disorders of Thyroid Gland
 Simple Goiter
 Under function  Hypothyroidism
 Over function  Thyrotoxicosis/hyperthyroidism
 Inflammation  Thyroiditis
 Tumors
 - Benign
 - Malignant

14. GOITER
 Is a diffuse enlargement of the thyroid gland
 Goiter is defined, somewhat arbitrarily, as a lateral lobe with a
volume greater than the thumb of the individual being examined
 On ultrasound, total thyroid volume exceeding 30 mL is
considered abnormal
 Thyroid function tests should be performed in all patients with
goiter to exclude thyrotoxicosis or hypothyroidism.
 Classification:
1. Simple
2. Toxic
3. Neoplastic
4. Inflammatory(thyroiditis)
5. Others (Amyloid etc)

15. 1.Simple Goiters
 Are asymptomatic and euthyroid.
1. DIFFUSE NONTOXIC (SIMPLE) GOITER
2. NONTOXIC MULTINODULAR GOITER

16. cont…
1. DIFFUSE NONTOXIC (SIMPLE) GOITER
 Is diffuse enlargement of the thyroid in the absence of
nodules and hyperthyroidism
 Worldwide, diffuse goiter is most commonly caused by
iodine deficiency and is termed endemic goiter when it
affects >5% of the population
 Endemic goiter may also be caused by exposure to
environmental goitrogens such as cassava root, which
contains a thiocyanate; vegetables of the Cruciferae family
(known as cruciferous vegetables) (e.g., Brussels sprouts,
cabbage, and cauliflower); and milk from regions where
goitrogens are present in grass

17. Cont…
 In non endemic regions, sporadic goiter occurs, and the
cause is usually unknown
 Thyroid enlargement in teenagers is sometimes referred to
as juvenile goiter
 Common in women than men, probably because of the
greater prevalence of underlying autoimmune disease and
the increased iodine demands associated with pregnancy.

18. Cont…
Iodine deficiency
 Common in the hilly parts
 Iodine goiter ( excessive iodine consumption, inhibits organic
binding of iodine-goiterogenic
 The World Health Organization (WHO) estimates that about 2
billion people are iodine-deficient
 In areas of relative iodine deficiency, there is an increased
prevalence of goiter and, when deficiency is severe,
hypothyroidism and cretinism

19. Cont…
 Cretinism is characterized by intellectual disability and growth retardation
and occurs when children who live in iodine deficient regions are not
treated with iodine or thyroid hormone to restore normal thyroid
hormone levels during early life
 These children are often born to mothers with iodine deficiency
 Oversupply of iodine, through supplements or foods enriched in iodine
(e.g., shellfish, kelp), is associated with an increased incidence of
autoimmune thyroid disease
 The World Health Organization recommends a daily iodine intake of 250
μg during pregnancy and lactation, and prenatal vitamins should contain
150 μg per tablet
 Urinary iodine is >100 μg/L in iodine-sufficient populations.

20. Cont…
THYROID FUNCTION IN PREGNANCY
 Five factors alter thyroid function in pregnancy:
(1) The transient increase in hCG during the first trimester,
which weakly stimulates the TSH-R
(2) The estrogen-induced rise in TBG during the first trimester,
which is sustained during pregnancy
(3) Alterations in the immune system, leading to the onset,
exacerbation, or amelioration of an underlying autoimmune
thyroid disease

21. Cont…
(4) Increased thyroid hormone metabolism by the placental type
III deiodinase; and
(5) Increased urinary iodide excretion, which can cause impaired
thyroid hormone production in areas of marginal iodine
sufficiency
 hCG-induced changes in thyroid function can result in
transient gestational hyperthyroidism that may be associated
with hyperemesis gravidarum, a condition characterized by
severe nausea and vomiting and risk of volume depletion

22. Cont…
2. NONTOXIC MULTINODULAR GOITER
 MNG or the presence of nodules in a thyroid of normal size
occurs in up to 12% of adults
 It is more common in iodine-deficient regions but also occurs
in regions of iodine sufficiency, reflecting multiple genetic,
autoimmune, and environmental influences on the
pathogenesis.

23. 2) Toxic goiter
a) Diffuse toxic goiter ( Grave’s disease or 1ry toxic goiter )
b)Toxic multinodular goiter
c) Toxic solitary nodular goiter

24. 3.THYROIDITIS
Causes of Thyroiditis:

25. 4.Neoplastic Goiter
1. Benign (adenoma)
2. Malignant tumors :
 Primary tumors :
• Papillary
• Follicular
• Anaplastic
• Medullary
• Malignant lymphoma
 Secondary tumors (mets. through blood spread
from melanoma, renal ca. breast ca. etc.

26. Complications of Goiter
1) Pressure effects:
a) dyspnoea ( tracheal compression )
b) dysphagia ( Oesophageal commpression )
c) horseness of voice ( pressure on the laryngeal nerve )
2) Haemorrhage: Nodule ( aspirate or operate )
3) Secondary thyrotoxicosis: 30% of multinodular goiters.
4) Malignancy: 25% of solitary nodular goiters and 8% of
multinodular goiters under go malignant changes

27. Retrosternal Goiter
 It is prolongation of the lower pole of the thyroid behind the sternum into
the superior mediastinum, with blood supply from inferior thyroid artery
branch
 Pemberton’s sign refers to facial and neck congestion due to jugular venous
obstruction when the arms are raised above the head, a maneuver that
draws the thyroid into the thoracic inlet.
 Clinical features: from pressure effect
1. Dyspnoea & cough
2. Dysphagia
3. Prominent veins occur at the root of the neck
 Respiratory flow measurements and CT or MRI should be used to evaluate
substernal goiter in patients with obstructive signs or symptoms
 Rx surgery indicated

28. PHYSICAL EXAMINATION
 In addition to the examination of the thyroid itself, the
physical examination should include a search for signs of
abnormal thyroid function and the extrathyroidal features of
ophthalmopathy and dermopathy
 Examination of the neck begins by inspecting the seated
patient from the front and side and noting any surgical scars,
obvious masses, or distended veins
 The thyroid can be palpated with both hands from behind or
while facing the patient, using the thumbs to palpate each
lobe

29. INVESTIGATIONS FOR THYROID DISEASES
1. Routine examinations
2. X-ray of the neck and chest
3. Isotope scan(radio-iodine):
 Hot nodule (autonomous)
 Warm nodule (graves’ disease)
 Cold nodule (haemorrhage,ca. Thyroiditis)
4. TFT(thyroid function test)
5. Indirect laryngoscopy
6. FNAC(fine needle aspiration cytology)
7. U/S
8. Autoantibody titers
9. Other scans (CT-scan, MRI)

30. Hyperthyroidism and Other Causes of Thyrotoxicosis
Hyperthyroidism:
 Is the result of excessive thyroid function
Thyrotoxicosis:
 Is defined as the state of thyroid hormone excess and is not synonymous
with hyperthyroidism
 However, the major etiologies of thyrotoxicosis are:
 Hyperthyroidism caused by Graves’ disease
 Toxic multinodular goiter (MNG), and
 Toxic adenomas
 Destructive thyroiditis (subacute or silent thyroiditis)
 Thyrotoxicosis factitia
 Teratomas of the ovary (struma ovarii) and functional metastatic follicular
carcinoma.

31. Causes of Thyrotoxicosis

32. Cont…

33. Cont…

34. TABLE 384-2 Signs and Symptoms of Thyrotoxicosis
(Descending Order of Frequency)

35. CNS signs of hyperthyroidism
 Tremors (tongue / hand )
 Sweating (hands)
 Hyperkinetic
 Intolerance to heat
 Preference to cold
 Excitability / irritability
 Restlessness

36. Eye signs of prim hyperthyroidism
 Exophthalmoses
 Eye lid spasm
 Proptosis (protrusion of eye ball seen on observation from
behind)
 Classical staring
 Loss of eye ball conversion
 Infrequent blinking
 Lid lags behind when asked to look up and down with speed
of finger’s movement.
 Keratitis
 Corneal ulcers
 conjunctivitis /blindness

37. CVS SIGNS OF PRIM. HYPERTHYROIDISM
 Despite the predominance of CVS signs in secondary
hyperthyroidism, in primary hyperthyroidism there are :
 Tachycardia
 Palpitations
 Extracystoles

38. Cont…

39. Cont…
DDX of Thyrotoxicosis:
 Panic attacks
 Mania
 Pheochromocytoma, and
 Weight loss associated with malignancy

40. LABORATORY EVALUATION
 A logical approach to thyroid testing is to first determine
whether TSH is suppressed, normal, or elevated with the use
of immunochemiluminometric assays (ICMAs) for TSH
 The finding of an abnormal TSH level must be followed by
measurements of circulating thyroid hormone levels to
confirm the diagnosis of hyperthyroidism (suppressed TSH) or
hypothyroidism (elevated TSH)

41. Cont…

42. TREATMENT
1. Using an antithyroid drug
2. Reducing the amount of thyroid tissue with radioiodine (131I)
treatment or
3. By thyroidectomy
 It has 3 aims :
1. To restore the pt. to euthyroid state
2. To reduce the functioning thyroid mass to a very
critical level
3. To reduce complications

43. Antithyroid drugs & others for the Rx. Of prim.
Hyperthyroidism
 Are used to restore the pts. to euthyroid state
 It takes 8-12 weeks or more.
 The usually used are :
 Antithyroid such as :
 PTU (200mg or more 8hrly..
 Carbimazole 10-15mg 6 or 8hrly
 Metimazole 10mg 6 or 8hrly
 Beta adrenergic blockers such as :
 Propranolol 10-20mg 8hrly (40mg tid in sever cases
 Nadolol 160mg./day
 Lugol’s iodine (10-12 drops po 8hrly for 14 days before surgery

44. Post. Op. complication of thyroid surgery
1. Hemorrhage
2. Resp. obstruction due to laryngeal edema
3. Recurrent laryngeal nerve palsy/paralysis
4. Hypothyroidism
5. Hypoparathyroidism
6. Thyrotoxic crisis (storm)
7. Wound infection
8. Keloid scar
9. Stitch granuloma

45. Advantages & disadvantages of each modality
of Rx. In prim. hyperthyroidism
 Medical RX.:
 Advantages :
 Avoids surgery
 No risk to life
 Is economical
 Disadvantages :
 Long duration of Rx.(1-2yrs.)
 Agranulocytosis
 Missed doses
 relapses

46. Advantages & disadvantages of each modality of
prim. Hyperthyroid.
SURGICAL Rx.. RADIOIODINE Rx.
 ADVANTAGES
 Permanent cure is high
 DISADVANTAGES
 Carries morbidity &
mortality
 Postop side effects
 Can recur
 ADVANTAGES
no surgery
No drugs
easy
 DISADVANTAGES
 No in pregnancy
 No in young girls
 Permanent
hypothyroidism

47. Treatment of Thyrotoxicosis
-1) Medical:
 Anti-thyroid drugs : Is to reduce the size & vascularity
 To decrease the vascularity, Lugol’s iodine ( 5% iodine in
10% potassium iodide 10 drops t.i.d is given for 14 days
a) Neomercazole 10mg t.i.d po
b) Propyl-thio-uracil 100mg t.i.d po
c) Carbamazepine 100mg po t.i.d untill eu-thyroid stage is
reached i.e sleeping PR comes to normal
Sedation:
a)Phenobarbital 30mg t.i.d or diazepam 5mg t.i.d to control
nervousness and anxiety of the patient

48. Hypothyroidism
 Deficient thyroid hormone secretion
 Primary hypothyroidism: due to thyroid disease(failure)
 Secondary hypothyroidism: due to TSH deficiency
 Tertiary hypothyroidism: due to TRH deficiency

49. Cont…

50. Cont…

51. Cont…

52. Cont…

53. Hypothyroidism: Treatment
 Replace with thyroxine (T4)
 T3 + T4 benefit unproven
 Typical replacement dose 1.6 mcg/kg
 Elderly or CAD: start low (0.025-0.05 mg/d), gradually increase
dose
 Maintain TSH within the normal range
 Wait 6 weeks after dose change
 Monitor yearly (noncompliance, reduced T4 clearance)

54. Subclincal Hypothyroidism
 Is subclinical hypothyroidism refers to biochemical
evidence of thyroid hormone deficiency in patients who
have few or no apparent clinical features of hypothyroidism
  TSH, normal FT4
 Most asymptomatic & don’t need Rx (monitor TSH q2-5y)
 Rx Indications:
 Increased risk of progression
 A woman who wishes to conceive or is pregnant or when
TSH levels are >10 mIU/L
 Most other patients can simply be monitored annually.

55. Myxedema Coma
 Rare condition in which an individual with long-standing
hypothyroidism presents with life-threatening
decompensation.
 Occurs in 0.1% of pts with hypothyoidism.
 Leads to decreased mental status, hypothermia, and other
symptoms
 It is a medical emergency with a high mortality rate
 Has a 20–40% mortality rate, despite intensive treatment

56. Cont…
 Almost always occurs in the elderly and is usually precipitated by
factors that impair respiration, such as drugs, pneumonia, congestive
heart failure, myocardial infarction, gastrointestinal bleeding, or
cerebrovascular accidents
 LT4 can initially be administered as a single IV bolus of 200–400 μg,
which serves as a loading dose, followed by a daily oral dose of 1.6
μg/kg per d, reduced by 25% if administered IV. If suitable IV
preparation is not available, the same initial dose of LT4 can be given
by nasogastric tubeParenteral hydrocortisone (50 mg every 6 h)
 Parenteral hydrocortisone (50 mg every 6 h)
 Supportive therapy

57. Carcinomas of the thyroid
gland(primaries)
 Thyroid gland is the only endocrine gland where :
 Malignant tumors are easily accessible for clinical
examination
 Malignant tumors occur in all ages and sex
 Malignant tumors spread by all routs (local,
lymphatic and blood)
 The malignant tumors of this gland have a good
prognosis if diagnosed and treated early.

58. Classification of primary thyroid tumors
I. Well differentiated
 Papillary
 follicular
II. Moderately differentiated
 Medullary Ca.
III. Poorly differentiated
 anaplastic
IV. Malignant lymphomas(from lymphatic tissue)

59. Incidence of malign. Thyroid tumors
 Papillary 60-65%
 Follicular 15-20%
 Anaplastic 10-12%
 Medullary 5-10%
 Others 10%

60. Clinical criterion for the diagnosis of thyroid Ca.
 Can be suspected even with only 1 feature
1. Rapidly growing thyroid’s swelling
2. Thyroid swelling with cervical L/nodes
3. Hard gland fixed to trachea
4. Thyroid swelling with hoarseness of the voice
5. Thyroid swelling with Berry sign positive
(impalpable carotid pulsation in anaplastic Ca.)
6. Kocher’s test (+) due to tracheal
infiltration(stridor)

61. Etiology
1) Papillary
 Accidental radiation to the neck
 Post Hashimoto’s Thyroiditis
2) Follicular
 MNG(endemic goiter)
3) Anaplastic (unknown)
4) Medullary
 Familial / sporadic
5) Lymphoma (Hashimoto is the possibility)

62. Carcinoma of the thyroid
-1) Papillary Ca
a.Occurs in children and young adults
b.Occurs in solitary adenoma of thyroid
c.Spread is by lymphatics
d.Metastases found in the cervical LN
-2) Follicular carcinoma
a.Occurs in adults
b.Occurs in multinodular goiter
c.Spread is by blood
d.Metastases is found in lungs & bone

63. Cont…
3) Anaplastic carcinoma
-a) Occurs in the old
-b) Occurs in de-novo ( in normal thyroid gland )
-c) Spread is by direct, lymphatics & blood
-d) Metastases found present in cervical LN, lung and bone
-4) Medulary carcinoma
-a) Does not arise from the thyroid tissue
-b) It arises from parafollicular cells which are derived from
ultimobranchial body
-c) It secretes calcitonin
-d) Spread is by lymphatics and blood
-e) Metastasis present in cervical LN,lung and bone

64. Treatment of carcinoma of the thyroid
 Total thyroidectomy
 Radioactive Iodine treatment
Indications:
 Patients over the age 45yr
 pts who are not in the reproductive period ( 15-40 yrs )
life for fear of mutation effect ( cleft lip, cleft
palate,hydrocephalus & club foot )
 Cardiopulmonary conditions-pts with this condition
having thyrotoxicosis
 Recurrent thyrotoxicosis after surgery
 Patient resistant to anti-thyroid drugs
 When the patient refuses surgery

65. Spread of thyroid Ca.
 Papillary -------lymphatic
 Follicular ------blood
 Anaplastic------local infiltration
 Medullary-------lymphatic & blood

66. Prognosis of thyroid Ca.
 Papillary---------excellent
 Follicular--------good
 Anaplastic-------worst
 Medullary--------bad

67.  THANK U!!!