Hypothyroidism

Question 1

What is the most common cause?

Answer 1

Chronic autoimmune thyroiditis (Hashimoto’s)

Question 2

What are the causes of hypothyroidism?

Answer 2

• Chronic autoimmune thyroiditis (Hashimoto’s)
• Iodine deficiency
• Drugs – lithium, amiodarone, antithyroid drugs
• Neck irradiation
• Post-surgery
• Hypo-pituitaries

Question 3

What is Chronic autoimmune thyroiditis (Hashimoto’s)?

Answer 3

T-cell infiltration into the thyroid, destruction of thyroid tissue
Autoantibodies to TPO and Tg

Question 4

What hormones are produced by the pituitary gland?

Answer 4

ANTERIOR - FLAT PeG

• F- follicle stimulating hormone (FSH)
• L - luteinizing hormone (LH)
• A - adrenocorticotropic hormone (ACTH)
• T - thyroid-stimulating hormone (TSH)
• P - prolactin
• E - endorphins
• G - growth hormone (GH)

POSTERIOR

• O - oxytocin
• V- vasopressin/ADH

Question 5

What symptoms discriminate between hypothyroidism and euthyroidim?

Answer 5

• Constipation
• Myalgia and muscle weakness
• Hoarse and deep voice
• Cold intolerance

Question 6

What are the signs of hypothyroidism?

Answer 6

Signs: BRADYCARDIA
•	Bradycardic
•	Reflexes relax slowly
•	Ataxia
•	Dry thin hair/skin
•	Yawning/drowsy/coma
•	Cold hands
•	Ascites +/- non-pitting oedema
•	Round puffy face/ double chin/ obese
•	Defeated demeanour
•	Immobile
•	Also: neuropathy, myopathy, goitre

Question 7

What are the symptoms of hypothyroidism?

Answer 7

• Coarse hair/ hair loss
• Dry skin
• Weight gain
• Constipation
• Amenorrhagia
• Fatigue
• Fluid retention
  Oedema
  Pleural effusion
  Ascites

Question 8

What would you ask in a patient Hx of hypothyroidism?

Answer 8

o Drug treatment – amiodarone, lithium or biotin
o Family Hx of thyroid/autoimmune disease
o Personal Hx of autoimmune diseases
o Previous radiotherapy to head or neck
o Hx of iodine deficiency
o Hx of Turner’s or Down’s syndrome

Question 9

What would the TFTs show to diagnose hypothyroidism?

Answer 9

• High TSH
• Low free T4

T3 is often maintained at the normal range
- Unhelpful as the body tires to maintain T3 levels by deioinating what T4 is available

Question 10

How would you treat hypothyroidism?

Answer 10

• Levothyroxine (T4) OD

50-150ug, mostly 100-125ug per day

Question 11

If TSH is high, how would you adjust levothyroxine dose?

Answer 11

Increase

Question 12

If TSH is low, how would you adjust levothyroxine dose?

Answer 12

Decrease

Question 13

What are the side effects of levothyroxine?

Answer 13

• AF

- Osteoporosis

Question 14

What is secondary hypothyroidism?

Answer 14

TSH deficiency due to pituitary or hypothalamic disease.

Question 15

What is a myxoedema coma?

Answer 15

Ultimate hypothyroid state before death

Question 16

What is hypothyroidism associated with?

Answer 16

Hypercholesterolaemia

Question 17

How would you treat hypothyroidism with hypercholesterolaemia?

Answer 17

Levothyroxine 75 ug

No need for statins as when you correct the thyroid abnormality, the cholesterol will come back to normal

Question 18

What is Sheenhan’s syndrome?

Answer 18

Lose life-threatening amount of blood during child-birth -> hypovolaemic shock -> damage to anterior pituitary gland

Question 19

How would you treat a pituitary problem?

Answer 19

• Corticosteroids
o Replacement of adrenal hormones due to ACTH deficiency
• Levothyroxine
• Oestradiol and progesterone

Question 20

What is amiodarone induced hypothyroidism (AIH)?

Answer 20

• Wolff-Chaikoff effect = high levels of circulating iodine inhibit thyroxine formation