Hyperthyroidism

Question 1

Epidemiology hyperthyroidism?

Answer 1

1% general population

F:M 5:1

Question 2

Signs and symptoms of hyperthyroidism?

Answer 2

THYROIDISM:
Tremor (fine)
HR up
Yawning (fatigued)
Restlessness
Oligomenorrhoea
Intolerance to heat
Diarrhoea
Irritability
Sweating
Muscle wasting / weight loss

Question 3

Rx of hyperthyroidism?

Answer 3

• Antithyroid drugs (e.g. propylthiouracil)
• B-blockers (symptom control)
• radioactive iodine thyroid ablation
• surgery

Question 4

Epidemiology of Graves disease?

Answer 4

F>M = 7:1
1.5-2% women
FHx common
HLA B8 and DR3
Associated with other inherited disorders (e.g. pernicious anaemia, Hashimoto's disease)

Question 5

Pathophysiology of Graves disease?

Answer 5

Defect in T suppressor cells > B cells produce TSI which binds TSH receptor, thus stimulating the thyroid gland.

Question 6

Aetiology of immune response in Graves disease?

Answer 6

Postpartum, iodine excess, lithium therapy, viral/bacterial infection, glucocorticoid withdrawal.

Question 7

Clinical features of Graves disease?

Answer 7

• Diffuse goitre +/- bruit (increased blood flow)
• Opthalmopathy
• Dermopathy: pretib myxedema (non-pitting)
• Acropachy (like clubbing)

Question 8

What are the clinical features of Graves opthalmopathy?

Answer 8

Proptosis, diplopia, conjunctival injection

PLUS signs of hyperthyroidism (lid lag, lid retraction, thyroid stare).

Question 9

Ix results in Graves disease?

Answer 9

• low TSH
• Increased T4
• Positive TSI

Question 10

Treatment Graves disease?

Answer 10

• Propylthiouracil
• B-blockers
• Thyroid ablation (radioactive I-131)
• Subtotal thyroidectomy

Question 11

What is the MoA of propylthiouracil?

Answer 11

Inhibits peroxidase- catalysed rxns:

• prevents organification of iodide
• blocks coupling of iodotyrosines
• inhibits peripheral deiodination of T4 to T3

Question 12

Side effects of propylthiouracil?

Answer 12

Major: Hepatitis, Agranulocytosis
Minor: rash, fever, arthralgias

Question 13

Pathophysiology of TMNG?

Answer 13

Autonomous thyroid hormone production from functioning adenoma hyper secreting T3/T4

Question 14

Clinical features of TMNG?

Answer 14

Goitre with adenomatous changes.

• Features of hyperthyroidism
• AF common presentation in elderly

Question 15

Ix in TMNG?

Answer 15

• Low TSH
• High T3/T4
• RAIU: increased nodular uptake. Remainder of gland suppressed.

Question 16

Rx TMNG?

Answer 16

• PTU to attain euthyroid state
• Radioactive ablation
• B blocker pre ablation
• Surgery

Question 17

Aetiology of thyroid storm?

Answer 17

Often precipitated by infection, trauma or surgery in hyperthyroid patient.

Question 18

DDx thyroid storm?

Answer 18

Sepsis, phaeochromocytoma, malignant hyperthermia, drug overdose.

Question 19

Clinical features of thyroid storm?

Answer 19

• Hyperthyroidism
• Extreme fever
• tachycardia / vascular collapse / arrhythmia (+/- CCF)
• N/V/D
• Hepatic failure with jaundice
• Confusion

Question 20

Ix results thyroid storm?

Answer 20

• Increased T3/4
• No TSH detected
• +/- anaemia, leukocytosis, hypercalcemia, elevated LFTs

Question 21

Rx thyroid storm?

Answer 21

• IV propranolol (tachycardia, decrease peripheral conversion T4->T3)
• High dose PTU
• Iodide (inhibit release of thyroid hormone)
• Dexamethasone (block peripheral conversion, lower body temp)
• Supportive: fluid and electrolytes, diuresis, vasopressors, cooling blanket, acetaminophen