thyroid

1. Diseases of
thyroid gland
Dr. Krishna

2. Goitre

3. Classification of goitre
1. Simple (non-toxic) goitre
– Diffuse
– Multi-nodular
– Colloid (large size, soft consistency,
due to iodine deficiency)
2. Toxic
– Diffuse (Graves’ disease)
– Multi-nodular (Plummer’s disease)
– Solitary nodule
3. Inflammatory : thyroiditis
4. Thyroid neoplasm: benign (adenoma),

5. Multi-nodular goitre
(MNG)

6. Etiology
1. Iodine excess
2. Iodine deficiency : Endemic, Sporadic,
Familial
3. Goitrogens ( eg. Cabbage, drugs like
phenytoin)

7. Pathogenesis of goitre
Iodine deficiency → Hypothyroidism
→Increased TSH
Diffuse
goitre
Follicles
grow
heterogeneo
usly
Nodular
goitre
Follicles
continue to
secrete T4
despite
subsequent
decrease in
TSH levels
Toxic
goitre
Diffuse
hypertrop
hy
of
thyroid
follicles
Increased
TSH

8. Hypothyroidism

9. Etiology

10. A. Primary hypothyroid (99% cases) : defect in
thyroid
• Iodine deficiency: common in developing
countries
• Hashimoto’s : common in developed
countries
• Subacute thyroiditis
• Thyroidectomy / iodine ablation / external RT
to neck
• Drug-induced: Lithium, amiodarone, anti-
thyroid drugs

11. Common features of
Hypothyroidism
Symptoms
Signs
• Tiredness, weakness
• Dry skin, hair loss
• Feeling cold
• Difficulty in
concentration
• Constipation
• Weight gain with poor
appetite
• Dyspnea & hoarse
voice
•
• Dry coarse skin
• Cool peripheral
extremities
• Puffy face &
extremities
(myxedema)
• Diffuse alopecia
• Bradycardia
• Peripheral edema
• Delayed reflex

12. Thyroiditis

13. Classification of Thyroiditis
1. Acute: bacterial, fungal, post-
radiation
2. Sub-acute
– Granulomatous / painful (De
Quervain's)
– Lymphocytic / painless
– Silent / post-partum
3. Chronic
– Autoimmune: Hashimoto, atrophic

14. Hashimoto’s Thyroiditis
• Commonest cause of hypothyroidism in
U.S.
• Associated with other autoimmune
diseases
– Pernicious anemia, rheumatoid
arthritis, vitiligo, type 1 diabetes

15. Investigations
• High TSH , Low T3 and T4
• Anti thyroid peroxidase antibodies (90%)
• Anti thyroglobulin antibodies (20 - 50%)
• Hyperthyroidism (5% )
• Histopathological exam
– Lymphocytic infiltration , atrophy of
thyroid follicles, absence of colloid,

16. Treatment
• Oral Thyroxine: 25 µg & increase
gradually to 100 -150 µg/day to get
serum TSH in normal range
• Primary adrenal insufficiency should be
ruled out (with synthetic ACTH
stimulation test) prior to initiating

17. Subacute Thyroiditis
• Synonym: De Quervain’s or granulomatous
thyroiditis
• Commonest cause of painful thyroiditis
• Etiology: inflammatory destruction of
thyroid gland often following upper
respiratory tract infection
• Clinical course: painful thyrotoxicosis (3-6

18. Clinical phases

19. • Diagnosis : Elevated ESR , low or absent uptake
of I 131
• Treatment
– NSAIDs for pain
– High doses of oral steroids in severe cases (↓
thyroid hormone binding proteins; ↓ peripheral
conversion of T4 to T3; ↓ inflammation
– Propranolol for symptomatic hyperthyroidism
• Anti-thyroid drugs not indicated since
hyperthyroidism results from release of T3 & T4
into circulation instead of thyroid hyper-function

20. Reidel’s Thyroiditis
• Etiology: unknown (? auto-immune)
• C/F: woody-hard thyroid gland with pain,
dysphagia or stridor (due to compression),
hypothyroidism, retroperitoneal fibrosis &
sclerosing cholangitis
• Diagnosis: MRI of thyroid, open biopsy
• HPE: replacement of thyroid gland with dense
fibrosis
• Rx: surgical debulking for compressive
symptoms, chemotherapy (tamoxifen or

21. Silent Thyroiditis
• Synonym : post-partum (within 1 year)
thyroiditis
• Clinical course: Hyperthyroid at
presentation → euthyroid → hypothyroid
(resolves within 1 year)
• Treatment

22. T4 T3 TSH Antibodies
Hashimoto'
s
thyroiditis
Low
Normal
or
Low
High
Anti-TPO + ve in
90%
Anti- Tg +ve in
50%
Subacute
thyroiditis
Low
Normal
or
Low
High -
Secondary
hypothyroi
d
Low
Normal
or Low
Low
or
norma
l
-
Tertiary
hypothyroi
d
Low
Normal
or Low
Low
or
norma
l
-

23. Sick euthyroid syndrome
• Low serum levels of T3 & T4 in clinically
euthyroid patients due to non-thyroidal
systemic illness
• Etiology: starvation, protein-energy
malnutrition, major trauma, myocardial
infarction, chronic renal failure, diabetic

24. • Pathogenesis: decreased peripheral
conversion of T4 to T3, decreased binding
of thyroid hormones to thyroxine-binding
globulin (TBG) caused by tumor necrosis
factor-α & Interleukin -1
• Diagnosis: decreased T3 & increased
reverse T3, T4 may be decreased, normal
TSH

26. Thyrotoxicosis

27. Etiology

28. 1. Primary hyperthyroidism: low serum TSH
– Graves' disease (commonest)
– Toxic adenoma
– Toxic multi-nodular goiter
– Iodine excess
2. Secondary hyperthyroidism: normal
serum TSH
– TSH producing pituitary adenoma
– Pituitary resistance to thyroid hormone
suppression

29. 3. Thyrotoxicosis without
hyperthyroidism:
– Subacute thyroiditis
– Thyrotoxicosis factitia
– Thyroid cancer metastasis
– Struma ovarii
– Amiodarone thyroiditis
– Radiation thyroiditis

30. Common symptoms & signs of
thyrotoxicosis
Symptoms
• Hyperactivity,
irritability
• Heat intolerance,
sweating
• Palpitations
• Fatigue
• Weight loss with ↑ed
appetite
• Diarrhea
• Polyuria
Signs
• Tachycardia
• Graves’
ophthalmopathy
• Atrial fibrillation in
elderly
• Tremor
• Goitre (thyroid
swelling)
• Warm, moist skin
• Proximal myopathy

31. Graves’ disease

32. • Commonest form of thyrotoxicosis (80-
90%)
• Female : male = 5-10 : 1;
• Age: 30-50 years
• Etiology:
– Thyroid Stimulating Immunoglobulins
(TSI)
• Antibodies against TSH receptor
(TSHR- Ab) which act as TSH receptor

33. Clinical features
• Symmetric, firm, rubbery, pulsating, warm,
goitre
• Thyrotoxicosis: palpitations, fine tremors,
diarrhea, excessive sweating, heat
intolerance, weight loss
• Eye signs and Graves’ ophthalmopathy

34. Eye signs
• Von Graefe: upper eyelid lag when pt
looks down
• Griffith: lower eyelid lag when pt looks
up
• Joffroy: absence of forehead wrinkling on
looking up
• Moebius: lack of medial convergence of
eyeballs
• Dalrymple: display of upper sclera
• Stellwag: staring look due to absence of

35. Graves’ ophthalmopathy (seen in 3%
cases)
• Infiltrative:
– Periorbital edema, proptosis, chemosis,
extraocular muscle palsy (commonly inferior
rectus), keratitis & loss of vision (optic nerve
involvement)
– Unaffected by thyrotoxicosis treatment
• Non-infiltrative:
– Lid retraction, stare & lid lag. Due to
hyperactivity of sympathetically innervated

36. Graves’ ophthalmopathy

37. Graves’s dermopathy
Thickening of skin
in anterior tibial
area due to
deposition of
glycos-
aminoglycans which
cause local fluid

38. Investigations
• Increased total T4 and T3 levels
• Ratio of T3 (ng/dL) to T4 (mcg/dL) > 20
• Suppressed serum TSH
• Thyroid scan: diffuse, symmetric, increased
uptake
• Thyroid antibodies: TSI (TSHR-Ab) specific for
Graves’ disease, anti-TPO and anti-Tg may be

39. Medical treatment
• Carbimazole: 5-15 mg TID for 12-18 months
• Propylthiouracil (PTU): 50-100 mg TID for
12-18 mth
– After 12-18 mths, positive TSHR-Ab =
90% risk of recurrence, negative TSHR-
Ab = 20% risk
• Propranolol: 20 mg TID ( for tremor &
tachycardia)

40. Radioactive iodine (I-131)
• Indications:
– Failed / refused / contraindicated medical
therapy or surgery
• Contraindications:
– Pregnancy, age < 30 yr , ophthalmopathy, low
RAIU (< 5%)
• 5 - 10 m Ci orally for 4 -12 wk
– Effective in 75% cases
• For thyrotoxicosis after 12 wks: double dose

41. Total Thyroidectomy
• Indications:
– Age < 30 yr, pregnancy, compression of
trachea by goitre, suspected cancer,
ophthalmopathy
• Pre-operative treatment:
– Propylthiouracil / Carbimazole: to make pt
euthyroid
–

42. Toxic multi-nodular goitre
• 2nd
common cause of thyrotoxicosis after
Graves’
• Emerges insidiously (over 10 years) from
non-toxic multi-nodular goiter due to
mutation in TSH receptor
• Serum TSH suppressed; T4 & T3 marginally
elevated
• Thyroid scan shows areas of hot & cold

43. Plummer’s toxic adenoma
• Occurs in younger pt (unlike Graves’ or
toxic MNG)
• Hyper-functioning thyroid nodule secretes
excess T3 & T4 → inhibits pituitary TSH
secretion → remaining thyroid gland
becomes quiescent
• I-123 thyroid scan shows hot nodule
• Rx: Carbimazole , Radioactive iodine

44. Diagnosis
Degree of
thyrotoxicos
is
Radioactive
iodine
uptake
Thyroid scan
Grave’s
disease
+ + + + + + + +
Homogenous
uptake
Toxic
multinodular
goitre
+ / + +
Normal or +
+
Multiple hot
& cold
nodules
Toxic
adenoma
+ / + +
Normal or +
+
Dominant
hot nodule
Thyrotoxic
subacute
thyroiditis
+ + + + < 1%
Absent
uptake

46. Thyroid nodule

48. Risk factors for malignancy in thyroid
nodule
• Age <20 or >45 years
• Male sex
• Size > 4 cm or rapid increase in size
• Hard nodule
• Fixed to adjacent structure
• Lymph node metastasis
• Vocal cord paralysis / hoarse voice
• H/o irradiation or family h/o thyroid

49. Thyroid malignancy

50. Classification
1. Follicular:
a. Differentiated: i. Papillary carcinoma (60
– 80% )
ii. Follicular carcinoma (10 –
20%)
b. Undifferentiated: Anaplastic carcinoma
(05 – 10%)

51. Clinical features of
thyroid neoplasm

52. • Thyroid gland enlargement (diffuse / nodular)
• Compression & infiltration features
– Recurrent laryngeal nerve: stridor &
hoarseness
– Superior mediastinal syndrome: engorged
neck veins
– Esophagus: dysphagia
– Sympathetic chain: Horner’s syndrome
– Tethering of overlying skin & muscles
• Mostly euthyroid ; hyper / hypothyroidism is
rare

53. Papillary carcinoma
• Etiology: previous external radiation to
head & neck
• 40 % rule: mean age 40 years, multi-
centric in 40 % cases, neck node
metastasis in 40% (to level 6)
• Female : male ratio - 3:1

54. Follicular carcinoma
• Mean age 50 years
• Female : male ratio is 3:1
• Well-encapsulated ( mistaken for
follicular adenoma)
• Tendency to invade thyroid capsule &
blood vessels

55. Medullary carcinoma
• Malignancy of calcitonin -producing C-cells
• Mutation of RET proto-oncogene present
• Sporadic
– 80% cases, no family history, other endocrine
tumors absent, normal physical appearance,
unilateral, unifocal, poorer prognosis, peak in
middle age to elderly
• Familial
– 20% cases, autosomal dominant inheritance
within family, multiple endocrine tumors

56. Anaplastic carcinoma
• Non-encapsulated, rapidly growing, extra-
thyroidal spread with compression of
trachea & esophagus
• Arise in pre-existing multi-nodular goiter
or well-differentiated thyroid cancers
• Node metastasis & pulmonary metastasis
common

57. TNM classification

58. Tumor:
T1: < 1 cm & limited to thyroid capsule
T2: > 1 to < 4 cm & limited to thyroid
capsule
T3: > 4 cm limited to thyroid capsule
T4: any size extending beyond thyroid
capsule
Neck lymph node enlargement:
NO: absent N1a: ipsilateral

59. Treatment of
thyroid malignancy

60. Papillary & follicular cancer
• Tumor size < 1 cm = Near total
thyroidectomy
• Tumor size >1 to < 4 cm = Total
thyroidectomy
• Tumor size > 4 cm = Total thyroidectomy
• N0 = antero-lateral neck resection (levels

61. Total thyroidectomy preferred in
papillary cancer
1.Papillary carcinoma is multi-centric
2.Revision surgery more difficult than
primary surgery
3.Limited surgery leads to:
• Local recurrence & decreased survival
rate
• Transformation into anaplastic

62. Other Therapies
1. Radioactive I 131
: for recurrent / residual
cancer
2. External radiotherapy:
• Inoperable cancer (invasion of trachea /
esophagus): 3000 cGy → debulking
surgery → 1500 cGy post-op
• Recurrent / residual cancer: 4500 – 5000
cGy

63. Medullary carcinoma
• Total thyroidectomy + modified radical
neck resection + resection of level 6 & 7
nodes if involved
• Life long Thyroxine (250 µg / day) aiming
to keep serum TSH level < 0.5 mU/L
• Hypercalcemia present: remove 31/2
parathyroids
• Pheochromocytoma present: B/L total

64. Anaplastic carcinoma
• External radiotherapy (3000 cGy) →
debulking surgery → post-op external
radiotherapy (1500 c Gy) + I.V.
Doxorubicin 20 mg / week
• Total thyroidectomy + radical neck
dissection + post-op external RT (4500 –
6000 c Gy) + I.V. Doxorubicin 20 mg /
week

65. Thyroid lymphoma
• 3-6 cycles of CHOP (cyclophosphamide,
doxorubicin, vincristine & prednisone)
followed by external radiotherapy to
thyroid, bilateral neck, supraclavicular
regions & mediastinum
• Isthmusectomy for biopsy & relieving

66. Thyroid surgery

67. Why is right RLN commonly
damaged in thyroid surgery?
• More superficial position
• Right nerve enters thyroid at 450
angle
whereas the left lies within tracheo-
esophageal groove
• Right nerve mostly passes superior to or
b/w branches of inferior thyroid artery;

68. • Lobectomy: removal of one thyroid lobe
• Isthmusectomy: removal of complete isthmus
• Hemi-thyroidectomy: lobectomy +
isthmusectomy
• Subtotal thyroidectomy : preservation of some
thyroid tissue in same and opposite tracheo-
esophageal groove (8 g) + 2 parathyroid glands
on opposite side
• Near-total thyroidectomy: preservation of
thyroid tissue in opposite tracheo-esophageal
groove (8 g) + 1 parathyroid gland on opposite

69. Types of Thyroid surgeries