GOOD AND SIMPLIFIED NOTES ON SOME COMMON THYROID DISEASES

1. THYROID DISEASES
BY PATRICK CHISALA
(BSC IN CLINICAL MEDICINE)

2. Thyroid
Diseases
PATRICK CHISALA

3. Introduction
• Anatomy
- Thyroid gland butterfly shaped
- Weighs 20-30grams
- Two lateral lobes, one pyramidal lobe
- Isthmus connects the lateral lobe

4. Anatomy
• Blood supply
- Superior thyroid artery
- Inferior thyroid artery
- Thyroid e ma artery direct branch from aorta
• venous drainage
- Superior thyroid vein
- Middle thyroid vein
- Inferior thyroid veins

5. Anatomy
• Nervous supply
Principal innervation of
the thyroid gland derives from the
autonomic nervous system.
Parasympathetic fibers come from the
vagus nerves, and sympathetic fibers are
distributed from the superior, middle,
and inferior ganglia of the sympathetic
trunk.
These small nerves enter the gland
along with the blood vessels.

6. • Lymphatic drainage
Lymphatic drainage of
the thyroid gland is extensive and
flows multidirectionally.
Immediate lymphatic
drainage courses to the
periglandular nodes; to the
prelaryngeal (Delphian),
pretracheal, and paratracheal
nodes along the recurrent
laryngeal nerve; and then to
mediastinal lymph nodes.

7. Anatomy
• Relations
- Investing fascia
- Trachea posterior
- Oesophagus
- Recurrent laryngeal nerve
- Superior laryngeal nerve

8. Embryology
• Develops in the floor of the pharynx and migrates from the
developing trachea to the permanent site at the base of the neck
• Differentiation begins at four weeks and is complete at six weeks
• The tract associated with migration is called Thyroglossal duct

9. Embryology
• The thyroid gland is the first of the body's endocrine glands to develop, on
approximately the 24th day of gestation.
• This occurs under the influence of fibroblast growth factor signaling
pathways.
• The thyroid originates from two main structures: the primitive pharynx and
the neural crest.
• The rudimentary lateral thyroid develops from neural crest cells, while the
median thyroid, which forms the bulk of the gland, arises from the
primitive pharynx.
• The thyroid gland forms as a proliferation of endodermal epithelial cells on
the median surface of the developing pharyngeal floor.
• The site of this development lies between 2 key structures, the tuberculum
impar and the copula, and is known as the foramen cecum

10. Physiology
• Thyroid is made of multiple acini (follicles)
• Each spherical follicle is surrounded by a single layer of cells and filled with
a pink staining protenaceous material called colloid
• When the gland is inactive the colloid is abundant, the follicles are large
and the cells lining them are flat
• Hormones secreted by the gland include thyroxine (T4) and tri-
iodothyroxine (T3)
• T3 is also produced in the peripheral tissues by de-iodination of T4
• Both hormones are iodine-containing amino acids
• T3 is more active than T4

11. Physiology
Iodine metabolism
- Iodine is the raw material
essential for thyroid
hormone synthesis
- The principle organs that
take up iodine is the thyroid
for hormone synthesis and
Kidneys for excretion
- T3 and T4 is metabolized in
the liver

12. Physiology
thyroid hormone functions
Target tissue Effect Mechanism
Adipose tissue Catabolic Stimulates
lipolysis
Muscle Catabolic Increase protein
break down
Heart Chronotropic and
ionotropic
Enhances
response to
catecholamines
Nervous system Developmental Promotes normal
brain deveopment
Gut Metabolic Increases
absorption of
Carbohydrate

13. Introduction
• Goitre – enlarged thyroid
- ‘Gutter’ Lattin means throat

14. Ectopic thyroid
Ectopic thyroid is defined as any thyroid tissue not located in its usual
position (i.e., anterior and lateral to the second, third, and fourth tracheal
rings). During development, the thyroid gland descends from the foramen
cecum at the base of the tongue to its location at the front of the trachea.
Lingual Thyroid
- Occurs as a swelling at the foramen caecum
- Usually the only thyroid. Common in females
- May cause dysphagia, dysphonia, respiratory obstruction or haemorrhage
RX- surgical and Non surgical methods.
Surgical treatment includes excision alone or excision with auto-
transplantation into muscle. Approach for excision is oral, transhyoid, and
lateral pharyngotomy.
Non-surgical treatment includes hormonal therapy and radioactive ablation.

15. Ectopic thyroid
Median ectopic thyroid
- Swelling in the upper part of the neck
- May be the only thyroid tissue present
Lateral thyroid
- Normal thyroid gland found laterally
- These should be considered malignant
Thyroglossal cyst
- May be present in any part of the thyroglossal tract
- Moves up when swallowing and protrusion of the tongue
- Fistula follows inadequate excision of the thyroglossal cyst

16. Thyroid swelling
• Classification
Diffuse hyperplastic-
Physiological
Pubertal
Pregnancy
Nodular (Single or Multinodular)

17. Thyroid swellings
Toxic Goiter
- Diffuse ( e.g. Graves)
- Nodular
- Toxic adenoma
Neoplastic
- Malignant

18. Thyroid Swelling
Inflammatory
Chronic lymphocytic thyroiditis
- Hashimoto’s disease
Granulomatous
- Dequervan’s thyroiditis
Infective
- Acute(bacterial, viral) Chronic(TB, syphilis)

19. Thyroid swelling
Thyroid cyst - Fluid-filled cavities (cysts) in
the thyroid most commonly result from
degenerating thyroid adenomas. Often,
solid components are mixed with fluid
in thyroid cysts. Cysts are usually
noncancerous, but they occasionally
contain cancerous solid components.
Rx -radioiodine or excision.
Dermoid cyst – Rx - excise
Solitary cyst-
Rx – Depends on FNAB cytologic specimen
results, management consists of observation,
levothyroxine suppression therapy, or
surgery. Patients with benign solitary thyroid
nodules may undergo observation or
levothyroxine suppression therapy as the
initial treatment modality

20. Thyroid swelling
• Others
Lipoma -Thyroid lipomas are characterized by the presence of a
capsule, which is absent in diffuse thyroid lipomatosis and is the main
differentiating feature . The pathophysiology of diffuse proliferation
of adipose tissue in the thyroid gland is unclear. Accurate diagnosis of
a single lipoma can be made clinically in up to 85% of cases. The
typical lipoma is a soft, doughy, non-tender, round, mobile mass.
Rx – lipectomy

21. Thyroid Malignancy
- Papillary
- Follicular
- Medullary
- Anaplastic
- Lymphoma

22. Papillary cancer
• Most common in the west
• Spread via lymphatics
• Slow growing
• Associated with exposure to radiation
Follicular
• Most common in Zambia
• Spread via blood vessels
• May present as pathological fracture
• Should be differentiated from follicular nodule

23. Anaplastic
• Poor prognosis
• Present late in life above 60yrs
• May be classified as small cell or large cell
• Local invasion of tissue
Medullary
• Endocrine
• MENS IIa, MENS 2b (Phaecromocytoma)
• May be sporadic or familial
• Secretes calcitonin as tumour marker

24. Lymphoma
• Good prognosis
• Medical treatment
• May be associated with immune suppression

25. Investigations
• Thyroid function tests
- T3, T4, TSH
. Thyroid antibodies
. Isotope scanning
. Ultrasound
. Soft tissue X-ray neck
. Indirect laryngoscopy

26. Investigations
• FNAC
• CT, MRI
• FBC/ESR

27. Treatment
• Thyroidectomy
• Thyroid iodine ablation
• Thyroxine

28. Thyroidectomy
• Total Thyroidectomy
• Hemithyroidectomy
• Subtotal thyroidectomy
• Near total thyroidectomy

29. HYPERTHYROIDISM
SYMPTOMS
• Hyperactivity/ irritability/ dysphoria
• Heat intolerance and sweating
• Palpitations
• Fatigue and weakness
• Weight loss with increase of appetite
• Diarrhoea
• Polyuria
• Oligomenorrhoea, loss of libido
SIGNS

30. Hyperthyroidism
Differences between primary and secondary hyperthyroidism
Primary thyrotoxicosis
1. Symptoms appear first, then thyroid swelling
2. Goitre is diffuse, smooth, firm or soft, both lobes
are
involved with thrill and bruit
3. Features are much more severe compared to
that ofsecondary toxicosis
4. Eye signs and exophthalmos are common
5. As it is an autoimmune disease, there may be
hepatosplenomegaly
Histologically, there is hyperplasia of acini, lined by
columnar epithelium, often containing vacuolated
colloidosis
1. Thyroid swelling appears first
2. Swelling is large nodular, obvious
3. Symptoms appear after long time, which is less
severe and slowly progressive compared to primary
toxicosis
4. Eye signs are not common
5. Cardiac features are more common

31. Graves Disease
• Autoimmune disorder
• Abs directed against TSH
receptor with intrinsic
activity. Thyroid stimulating
immunoglobulins bind and
activate thyrotropin
receptors causing thyroid
gland to grow and thyroid
follicles to increase thyroid
hormone synthesis
• Responsible for 60-80% of
Thyrotoxicosis
• More common in women
than me
• Dermopathy – legs- pretibial
myxedema
N - no signs or symptoms
O – only signs (lid retraction or lag) no symptoms
S – soft tissue involvement (peri-orbital oedema)
P – proptosis (>22 mm)(Hertl’s test)
E – extra ocular muscle involvement (diplopia)
C – corneal involvement (keratitis)
S – sight loss (compression of the optic nerve)
Goiter with diffuse bruit
Opthalmopathy – Non infiltrative – grittiness,
redness, lacrimation, lid lag, lid retraction.
Infiltrative - exophthalmos
Dermopathy – hands –
onycholysis,
acropathy(acropachy)
Dermopathy – legs-
pretibial myxedema

32. Treatment of Graves Disease
• Reduce thyroid hormone production or reduce the
amount of thyroid tissue
• Antithyroid drugs: propyl-thiouracil, carbimazole
• Radioiodine
• Subtotal thyroidectomy – relapse after antithyroid
therapy, pregnancy, young people?
• Symptomatic treatment
• Propranolol

33. SYMPTOMS
• Dry skin, cool extremities
• Puffy face, hands and
feet
• Delayed tendon reflex
relaxation
• Carpal tunnel syndrome
• Bradycardia
• Diffuse alopecia
• Serous cavity effusions
• Tiredness and
weakness
• Dry skin
• Feeling cold
• Hair loss
• Difficulty in
concentrating and
poor memory
• Constipation
• Weight gain with
poor appetite
• Hoarse voice
• Menorrhagia, later
oligo and
amenorrhoea
• Paresthesias
• Impaired hearing

34. Hypothyroidism
• Under- active thyroid gland
• This is a condition with less thyroid hormone production.
• Usually a primary disease of the thyroid
• May be secondary to hypothalamic pituitary axis
• In secondary hypothyroidism, TSH levels are low.
• Common in older women
• May present with puffy moon face

35. Causes of Hypothyroidism
 Drugs: excess iodine,
lithium, anti-thyroid
drugs, interferons,
amiodarone etc.
 Iodine deficiency
 Infiltrative disorders
of the thyroid:
amyloidosis,
sarcoidosis,haemochr
omatosis,
scleroderma
INVESTIGATIONS

37. Treatment of Hypothyroidism
• Levothyroxine
• If no residual thyroid function 1.5 μg/kg/day
• Patients under age 60, without cardiac disease can be started on 50 – 100
μg/day. Dose adjusted according to TSH levels
• In elderly especially those with CAD the starting dose should be much less
(12.5 – 25 μg/day)

38. Thyroiditis
• Acute: rare and due to suppurative infection of the thyroid
• Sub acute: also termed de Quervains thyroiditis/ granulomatous
thyroiditis – mostly viral origin
• Chronic thyroiditis: mostly autoimmune (Hashimoto’s)

39. Acute Thyroiditis
• Bacterial – Staph, Strep
• Fungal – Aspergillus, Candida, Histoplasma, Pneumocystis
• Radiation thyroiditis
• Amiodarone (acute/ sub acute)
Painful thyroid, ESR usually elevated, thyroid function normal

40. Sub Acute Thyroiditis
Viral (granulomatous) – Mumps, coxsackie, influenza, adeno and
echoviruses
Mostly affects middle aged women, Three phases, painful enlarged
thyroid, usually complete resolution
Rx: NSAIDS and glucocorticoids if necessary

41. Sub Acute Thyroiditis (cont)
Silent thyroiditis
No tenderness of thyroid
Occur mostly 3 – 6 months after pregnancy
3 phases: hyperhyporesolution, last 12 to 20
weeks
ESR normal, TPO Abs present
Usually no treatment necessary

42. Sub Acute Thyroiditis (cont)
Silent thyroiditis
No tenderness of thyroid
Occur mostly 3 – 6 months after pregnancy
3 phases: hyperhyporesolution, last 12 to 20 weeks
ESR normal, TPO(thyroid peroxidase) Abs present
Usually no treatment necessary

43. Chronic Thyroiditis
Hashimoto’s
• Autoimmune
• Initially goiter later very little thyroid
tissue
• Rarely associated with pain
• Insidious onset and progression
• Most common cause of hypothyroidism
• TPO abs present (90 – 95%)

44. Chronic Thyroiditis
Reidel’s
• Rare
• Middle aged women
• Insidious painless
• Symptoms due to compression
• Dense fibrosis develop
• Usually no thyroid function impairment
• Most pts are euthyroid, and some may have hypo, rarely hyper.
• Steroids may be used

45. Thyroiditis
• The most common form of thyroiditis is Hashimoto thyroiditis, this is
also the most common cause of long term hypothyroidism
• The outcome of all other types of thyroiditis is good with eventual
return to normal thyroid function

47. THANK YOU