1. Thyroid Gland Hypothyroidism & Hyperthyroidism
Dr. Zahoor

2. Thyroid Gland
The metabolism of Virtually all nucleated cells of many tissues in the body is controlled by thyroid hormone
Over activity (Hyperthyroidism) and under activity (Hypothyroidism) of the gland are most common of all endocrine problems

3. Thyroid Gland Anatomy: It has two lateral lobes connected by Isthmus
It moves on swallowing as it is attached to thyroid cartilage and trachea
Embryologically it originates from the base of the tongue and then descends therefore sometimes remnants of thyroid can be found at the base of tongue (Lingual thyroid)

4. Thyroid Gland Anatomy:
Thyroid gland has follicles lined by cuboidal epithelial cells. Inside the follicle is colloid (Iodinated glycoprotein Thyroglobulin) which is synthesized by follicular cells.
Each follicle is surrounded by basement membrane, between follicular cells there are parafollicular cells containing calcitonin secreting C cells

5. Follicular & parafollicular cells

6. Thyroid Gland Physiology: Thyroid gland synthesizes two hormones
T3 – Triiodothyronin: acts at Cellular level
T4 - L – Thyroxin: which is prehormone
More T4 is produced than T3 in thyroid but T4 is converted to T3 in periphery

7. Thyroid Gland Physiology:
In Plasma more than 99% of T4 and T3 is bound to protein (Thyroxin Binding Globulin TBG, Thyroid Binding PreAlbumin TBPA) and Albumin

8. Thyroid Gland Physiology:
Control of hypothalamic–pituitary–thyroid axis:
Hypothalamus produces TRH – Thyrotropin releasing hormone, it stimulates pituitary to secrete TSH – Thyroid Stimulating Hormone.
TSH stimulates activity of Thyroid Follicular cells
T3 & T4 are secreted in circulation by follicular cells
T3 & T4 has negative feedback effect on Hypothalamus and pituitary

9. Physiological Effect of Thyroid Hormone

10. Primary Hypothyroidism
Thyroid Gland
Thyroid Function Test:
Free T4 Free T3 and TSH are available and test can be done at anytime of the day
Free T3 ↑
Free T4 ↑
↓ TSH
Thyrotoxicosis 1
T3 N or Low
Free T4 ↓
Or Low Normal
TSH ↑
Primary Hypothyroidism 2
Free T4 ↓ or Low Normal
TSH Deficiency
(Pituitary) 3

11. HYPOTHYROIDSM

12. Hypothyroidism
It is usually primary due to disease of thyroid, but may be secondary to hypothalamic – pituitary disease (decreased TSH drive)
It is more common in females

14. Hypothyroidism Autoimmune Hypothyroidism
It is most common cause and associated with antithyroid antibodies
It is six time more common in females
It has association with other autoimmune diseases e.g. pernicious anemia, Vitiligo etc.

15. Hypothyroidism Hashimotos Thyroiditis
This is a form of autoimmune thyroiditis, more common in females and occurs in late middle age
Causes atrophic changes and regeneration leading to goiter formation
TPO ( Thyroid per oxidase) antibodies are present in high titer (> 1000 IU/L)
Patient may be hypothyroid or Euthyroid, though they may go through initial toxic phase
Levothyroxin is given when patient is hypothyroid

16. Hypothyroidism Post Partum Thyroiditis
This is transient phenomena, observed after pregnancy
It may cause Hyperthyroidism, Hypothyroidism
It is due to result of modifications to the immune system in pregnancy
It is usually self limiting or leads to hypothyroidism

17. Defects of Thyroid Hormone Synthesis
Iodine Deficiency
Iodine is required for synthesis of T3 & T4
We take iodine in diet, if deficient than people get goiter ( due to TSH stimulation)
Patient may be euthyroid or hypothyroid
Iodine deficiency is problem in many countries e.g. Netherlands, India, Asia, Africa, Russia
Efforts are made to prevent iodine deficiency by adding iodine in common salt.

18. Defects of Thyroid Hormone Synthesis
Dyshormonogenesis
Rare condition, due to genetic defect in the synthesis of thyroid hormone
Patient develops hypothyroidism with goiter
Note—Some people have Genetic defect causing sensorineural deafness due to mutation at chromosome 7, they have goiter( hypothyroid) also and this condition is called Pendred Syndrome

19. Hypothyroidism Symptoms and Signs
*Bold type indicate important symptoms and signs

20. Hypothyroidism

21. Hypothyroidism Myxoedema:
It refers to Hypothyroidism plus accumulation of mucopolysaccharide in subcutaneous tissue
Patient is slow, thick skin, dry hair, deep voice, weight gain, cold intolerance, bradycardia, constipation

22. Hypothyroidism Children with Hypothyroidism:
Have slow growth velocity
Have poor school performance
Young Females with Hypothyroidism
Hypothyroidism should be excluded in all women with Oligomenorrhoea, amenorrhoea, menorrhagia, infertility, Hyperprolactinimia

23. Hypothyroidism Investigations: Serum Free T3, Free T4 and TSH
High TSH confirms primary Hypothyroidism, free T4 is low
Other investigations:
Anemia – usually normocytic normochromic
But may be Macrocytic (due to associated Pernicious anemia )
Microcytic – in women due to menorrhagia

24. Increase serum creatinine Kinase – with associated Myopathy
Hypothyroidism
Other Investigations:
Increase serum creatinine Kinase – with associated Myopathy
Hypercholesterolemia and hypertriglyceridaemia
Hyponatremia – due to increase ADH

25. Hypothyroidism Treatment: Thyroxin – T4 is given for life
Dose 100 Micrgram daily for young patients
50 microgram for small, old patient to be increased to 100 microgram after 2 – 4 days
If patient has IHD start with 25 Microgram daily and increase dose at 3 – 4 week interval ( monitor by serial ECG)
Aim of treatment is to restore T4 & TSH within normal range
Improvement on T4 takes 2 weeks or more and resolution of symptoms takes about 6 months

26. Hypothyroidism Treatment for Myxoedema:
It is severe hypothyroidism and patient may present with confusion or even COMA
Myxoedema Coma is very rare, hypothermia is often present and patient may have severe cardiac failure, pericardial effusion, hypoventilation, hypoglycemia, hyponatremia
Mortality is high

27. Hypothyroidism Treatment for Myxoedema:
T3 orally or IV microgram 8 hourly O2
Hydrocortisone 100 mg IV 8 Hourly
Glucose infusion
Gradual rewarming

28. HYPERTHYROIDISM

29. Hyperthyroidism
Hyperthyroidism (Thyrotoxicosis) is common, affecting 2-5% of all females
Female-Male ratio 5:1
Age years
More than 99% cases are caused by intrinsic thyroid disease, pituitary cause is extremely rare

31. Graves Disease
This is most common cause of hyperthyroidism and is due to autoimmune process
IgG antibodies bind to TSH receptors in the thyroid and stimulate thyroid hormone production (IgG behaves like TSH)
TSH receptor antibodies (TSHR – Ab antibodies) are specific for Graves Disease
Graves Disease is associated with autoimmune disorders such as pernicious anemia, Vitiligo and myasthenia gravis

32. Other Causes of Hyperthyroidism/Thyrotoxicosis
Solitary toxic adenoma/nodule
It is cause of 5% cases of hyperthyroidism usually remit after antithyroid drugs
Toxic multinodular goitre
Commonly occurs in older woman
Anti thyroid drugs control hyperthyroidism

33. Other Causes of Hyperthyroidism/Thyrotoxicosis
De Quervain’s thyroditis
This is transient hyperthyroidism due to inflammatory process, probably viral in origin
There is fever, maliase, pain in the neck, tachycardia and local thyroid tenderness
Thyroid function test show
- Hyperthyroidism
- Increased ESR

34. Other Causes of Hyperthyroidism/Thyrotoxicosis
De Quervain’s thyroditis
Thyroid function test show (cont)
- Thyroid uptake show suppression of uptake in acute
phase
- Hypothyroidism, usually transient, may follow after
few weeks
Treatment of acute phase
- Aspirin
- Predinisolone

35. Other Causes of Hyperthyroidism/Thyrotoxicosis
Amiodarone – induced thyrotoxicosis (AIT)
Amiodarone is anti arrhythmic drug – class 111 and causes hyperthyroidism

36. Symptoms and Signs of Hyperthyroidism
*Bold type indicate important symptoms and signs

37. Clinical Features of Hyperthyroidism
The eye signs of lid lag and stare
May occur with hyperthyroidism of any cause
Graves dermopathy
Pretibial myxoedema – is in filtration of the skin on
the shin
Thyroid Acropachy – very rare and consist of clubbing, swollen fingers and periosteal new bone formation

38. Clinical Features of Hyperthyroidism (cont)
Atrial Fibrillation in the elderly
Is frequent presentation
Children with hyperthyroidism
May present – excessive height, hyperactivity

39. Pretibial myxoedema

40. Differential Diagnosis
Anxiety (Sympathetic Stimulation)
There is tachycardia, tremor, but cold clammy hand
In hyperthyroidism,
there is tachycardia tremor, warm hands, eye signs, diffused goitre, weight loss despite increase appetide

41. Hyperthyroidism Investigations
Serum TSH is suppressed, free T4 or T3 are raised
Thyroid per oxidase (TPO) and thyroglobulin antibodies are present in most cases of Graves disease
Thyroid stimulating immunoglobulin (TSI) are present in Graves disease

42. Hyperthyroidism Treatment Three options are available
1. Anti thyroid drugs
2. Radio active iodine
3. Surgery
Carbimazole – 20-40mg/day 8 hourly or single dose
Propylthioracial (PTU) – mg 8 hourly
They inhibit the formation of thyroid hormones
Propranolol (Beta Blocker) is used for symptomatic relief

43. Hyperthyroidism Treatment Side effects of drugs
Carbimazole – rash, nausea, vomiting, arthralgia, agranulocytosis, jaundice
PTU – rash, nausea, vomiting, agranulocytosis
NOTE – As agranulocytosis is the side effect, therefore, patient is advised if he has sore throat, he should report to hospital for investigation

44. Hyperthyroidism Treatment (cont) 2. Radioactive Iodine – 131Iodine
Can be given to all patients
Is contraindicated in pregnancy and during breast feeding
3. Surgery
Subtotal thyroidectomy/thyroidectamy
Side effects – laryngeal nerve palsy occur in 1%
Transient hypocalcemia up to 10%
Permanent hypoparathyroidism < 1%

45. Hyperthyroidism in Pregnancy
During pregnancy Propylthioracial (PTU) is preferred because there are reports of congenital abnormalities with Carbimazole
TSI – thyroid stimulating immunoglobulin cross the placenta and stimulate fetal thyroid
Carbimazole and PTU cross the placenta
T4 (Thyroxin) very poorly crosses the placenta
If necessary surgery can be performed in second semester of the pregnancy

46. Thank you