Thyroid Dysfunction

Question 1

What are the three broad categories of thyroid disorders?

Answer 1

1. Thyroid function abnormalities (hypo- or hyperthyroidism)
2. Thyroid mass or structural change
3. Combination of both

Question 2

What is hypothyroidism?

Answer 2

Reduced thyroid hormone secretion; underactive thyroid.

Question 3

What is hyperthyroidism?

Answer 3

• Increased thyroid hormone production
• overactive thyroid.

Question 4

Describe the anatomy of the thyroid gland.

Answer 4

• Two lobes connected by an isthmus
• each lobe ~5×3×2 cm
• palpable
  -moves with swallowing

Question 5

How is thyroid hormone secretion controlled?

Answer 5

By a classic negative feedback loop involving the hypothalamus (TRH), pituitary (TSH), and thyroid (T3/T4).

Question 6

Which thyroid hormone is more biologically active?

Answer 6

T3 (five times more bioactive than T4).

Question 7

Where is T4 converted to T3?

Answer 7

In peripheral tissues.

Question 8

What form of thyroid hormone is biologically active?

Answer 8

Only the free (unbound) hormone fraction.

Question 9

What is hyperthyroidism?

Answer 9

Excess production of thyroid hormone by the thyroid gland.

Question 10

What is thyrotoxicosis?

Answer 10

The clinical and biochemical state of thyroid hormone excess; may be due to hyperthyroidism, thyroiditis, or exogenous thyroid hormone intake.

Question 11

What are the common causes of hyperthyroidism?

Answer 11

• Graves’ disease
• Multinodular goitre
• Toxic (single) nodule
• Thyroiditis (including post-partum)
• Drugs

Question 12

In which age group is Graves’ disease more common?

Answer 12

Younger individuals.

Question 13

What is the female:male ratio in Graves’ disease vs nodular thyroid disease?

Answer 13

• Graves’: 10:1
• Nodular disease: 1:1

Question 14

Which thyroid disorder is autoimmune?

Answer 14

Graves’ disease (positive TPO and TSH receptor antibodies).

Question 15

Which thyroid disorder is more likely to be familial?

Answer 15

Graves’ disease.

Question 16

Which thyroid disorder usually presents gradually and persistently?

Answer 16

Nodular thyroid disease.

Question 17

Which thyroid disorder may be self-limiting and more severe in thyrotoxicosis?

Answer 17

Graves’ disease.

Question 18

What are key symptoms of hyperthyroidism?

Answer 18

• Anxiety
• emotional lability
• tremor
• palpitations
• weakness
• heat intolerance
• sweating
• weight loss despite normal/increased appetite.

Question 19

How might older people present with hyperthyroidism?

Answer 19

Weight loss or heart failure symptoms only.

Question 20

What are characteristic clinical signs of hyperthyroidism?

Answer 20

• Rapid speech, agitation
• Lid retraction/lag
• Warm, moist skin
• Pretibial myxoedema (Graves’)
• Tremor, proximal myopathy
• Goitre (size depends on cause)
• Tachycardia or atrial fibrillation

Question 21

What are typical lab findings in hyperthyroidism?

Answer 21

• Raised FT3 and FT4
• Suppressed TSH (<0.01 mU/L)
• ± Positive TPO and TSH receptor antibodies

Question 22

What imaging can be used in hyperthyroidism?

Answer 22

Thyroid scintigraphy or ultrasound (not always routine).

Question 23

What are the medical treatment options?

Answer 23

Carbimazole or propylthiouracil (block thyroid hormone synthesis).

Question 24

What are the surgical options?

Answer 24

Partial or total thyroidectomy.

Question 25

What radiotherapy option is available for hyperthyroidism?

Answer 25

Radioactive iodine therapy.

Question 26

What medication provides symptomatic relief in hyperthyroidism?

Answer 26

Beta-blockers.

Question 27

What is hypothyroidism?

Answer 27

Reduced production of thyroid hormone.

Question 28

In whom is hypothyroidism most common?

Answer 28

Females, especially those over 65 years (5–15% incidence).

Question 29

What are the two main types of hypothyroidism?

Answer 29

- Primary (thyroid gland failure) - Secondary (pituitary or hypothalamic failure)

Question 30

What are typical lab findings in primary hypothyroidism?

Answer 30

- Raised TSH - Low FT4 and FT3 - Positive TPO antibodies in autoimmune cases

Question 31

Is imaging usually needed in hypothyroidism?

Answer 31

Rarely.

Question 32

What are common causes of hypothyroidism?

Answer 32

- Autoimmune (Hashimoto’s thyroiditis) - Iatrogenic (surgery, radioiodine) - Drugs (affecting hormone production, metabolism, or absorption)

Question 33

What are the two mechanisms causing hypothyroid symptoms?

Answer 33

1. General metabolic slowing 2. Tissue deposition of glycosaminoglycans

Question 34

What symptoms result from metabolic slowing?

Answer 34

Fatigue, cold intolerance, weight gain.

Question 35

What symptoms result from glycosaminoglycan deposition?

Answer 35

Skin changes, hoarse voice, enlarged tongue (macroglossia).

Question 36

What is the standard treatment for hypothyroidism?

Answer 36

Levothyroxine (usually 75–175 mcg daily).

Question 37

What must be considered when treating hypothyroidism in patients with heart disease?

Answer 37

Start at lower doses and increase gradually due to risk of cardiac stress.

Question 38

What is the “T3/T4 controversy”?

Answer 38

Debate over whether combined T3/T4 therapy is superior to levothyroxine alone (not yet proven).

Question 39

What is subclinical hyperthyroidism?

Answer 39

Low TSH with normal FT4 and FT3.

Question 40

What is subclinical hypothyroidism?

Answer 40

Raised TSH with normal FT4 and FT3.

Question 41

Do subclinical thyroid disorders cause symptoms?

Answer 41

No, they are usually asymptomatic.

Question 42

When might subclinical thyroid disorders need investigation?

Answer 42

Depending on age, autoantibody presence, and possible emerging symptoms.

Question 43

What is a goitre?

Answer 43

A palpable enlargement of the thyroid gland.

Question 44

Do most goitres cause compressive symptoms?

Answer 44

No, even large ones rarely do.

Question 45

When can goitre cause compression?

Answer 45

If asymmetric or substernal in location.

Question 46

What proportion of goitres are substernal?

Answer 46

Rare — about 1:2000 to 1:5000.

Question 47

What thyroid states can patients with goitre be in?

Answer 47

Euthyroid, hyperthyroid, or hypothyroid.

Question 48

What are common symptoms of a substernal goitre?

Answer 48

Wheeze, dyspnoea, and cough.

Question 49

What are common causes of substernal goitre?

Answer 49

- Multinodular goitre (51%) - Large follicular adenoma (44%)

Question 50

How are thyroid nodules often detected?

Answer 50

As a visible neck swelling or incidentally on imaging (CT, MRI, carotid ultrasound).

Question 51

Why is it important to evaluate thyroid nodules?

Answer 51

To exclude thyroid cancer.

Question 52

What investigations are used for thyroid nodules?

Answer 52

- Thyroid function tests and autoantibodies - Ultrasound - Fine-needle aspiration cytology (FNAC) - Scintigraphy (uptake scan)

Question 53

What does increased uptake on a thyroid isotope scan suggest?

Answer 53

A benign, functioning lesion.