PBL 3 - Hyperthyroidism

Question 1

List some of the symptoms of hyperthyroidism. (10)

What are the symptoms specific to Grave’s disease? (4)

Answer 1

GENERAL HYPERTHYROIDISM

1. Weight loss
2. Heat intolerance
3. Palpitations
4. Dyspnoea
5. Irritability
6. Fatigue
7. Sweating
8. Tremor
9. Tachycardia
10. Hypertension

GRAVE’S DISEASE:

1. Ophthalmopathy
   a. Exophthalmus
   b. Periorbital oedema
   c. Lid retraction/lag
   d. Diplopia
   e. Nerve compression
2. Dermopathy
3. Pretibial myxoedema
4. Finger clubbing

Question 2

List the causes of hyperthyroidism. Consider:

a) Primary hyperthyroidism (4)
b) Secondary hyperthyroidism (7)

Answer 2

PRIMARY HYPERTHYROIDISM:
Graves' disease
Toxic multinodular goitre
Toxic adenoma
Ectopic thyroid tissue, e.g.
---Metastatic follicular cancer
---Struma ovarii

SECONDARY HYPERTHYROIDISM:
TSHoma
Exogenous thyroid hormones
Subacute de Quervain's thyroiditis (post-viral)
Drug-induced (e.g. amiodarone)
Pregnancy
TB
Thyroid hormone resistance syndrome

Question 3

Define Grave’s disease.

Answer 3

Autoimmune hyperthyroidism caused by autoantibodies; features classic signs of hyperthyroidism as well as additional symptoms specific to Grave’s disease

Question 4

Describe the pathophysiology of Grave’s disease. (3)

Answer 4

1. High levels of circulating thyroid hormones.
2. Effects of increased hormone levels:
   a. Increased metabolism
   b. Increased sympathetic nervous activity
3. Autoimmune antibodies:
   a. TSH-receptor antibodies
   - –Stimulate normal TSH receptors to increase stimulation of the thyroid gland

Question 5

Describe the investigations that can be done for hyperthyroidism. (3)

Answer 5

1. TSH levels
2. Serum free T4 levels
   a. Free T4 index
   b. Measure of T4 protein binding
   c. Thyroxine binding globulin levels
3. Serum/total T3 levels

Question 6

What is thyrotoxicosis?

Answer 6

Hyperthyroidism

Question 7

What is thyroid crisis/thyroid storm?

Answer 7

A life-threatening condition due to a severe worsening of previously undiagnosed or inadequately treated thyrotoxicosis; often presents with fever, agitation, nausea, vomiting and abdominal pain

Question 8

List the causes of thyroid storm. (8)

Answer 8

1. Infection
2. Diabetic ketoacidosis
3. Physical/emotional trauma
4. Thyroidectomy
5. Childbirth
6. Surgery
7. Trauma
8. No obvious cause

Question 9

List the clinical features of thyroid storm. (5)

Answer 9

1. Very high fever
2. Extreme cardiovascular effects
   a. Tachycardia
   b. Congestive heart failure
   c. Angina
3. Severe CNS effects
   a. Agitation
   b. Delirium
   c. Psychotic episodes
   d. Coma
4. Altered liver function
5. Biochemical features:
   a. Hyperglycaemia
   b. Hypercalcaemia
   c. High WBC count
   d. Anaemia

Question 10

Describe the treatment of hyperthyroidism. (3)

Answer 10

1. Thionamides
   a. Carbimazole/methimazole
   b. Propylthiouracil (PTU)
2. Radioactive iodine
   a. Uses 131iodine
3. Thyroidectomy

Question 11

What is the mechanism of action of thionamides?

Answer 11

1. Inhibit thyroid peroxidase
   a. Therefore there is no hormone synthesis
2. Inhibit peripheral T4 to T3 conversion
   a. Especially PTU - this causes a more rapid effect

Question 12

What are the side effects of thionamides? (2)

Answer 12

1. Maculopapular pruritic rash
2. Agranulocytosis
   a. Presents with sore throat, fever

Question 13

List the SWEATING mnemonic for symptoms of hyperthyroidism.

Answer 13

Sweating
Weight loss
Emotional lability
Appetite increased
Tremor/Tachycardia
Intolerance to heat/Irregular menstruation/Irritability
Nervousness
Goitre/Gastrointestinal problems

Question 14

List the THYROIDISM mnemonic for symptoms of hyperthyroidism.

Answer 14

Tremor/Tachycardia
Heart rate increased
Yawning (fatigue)
Restlessness
Oligomenorrhoea/amenorrhoea
Intolerance to heat
Diarrhoea
Irritability
Sweating
Muscle wasting/weight loss

Question 15

Which thionamide is used preferentially in pregnancy?

Answer 15

Propylthiouracil

Methimazole may cause aplasia cutis in foetus

Question 16

What needs to be monitored when giving propylthiouracil?

Answer 16

LFTs

Question 17

Describe the clinical signs of hyperthyroidism. (9)

Answer 17

Tachycardia
Arrhythmias, esp. AF
Warm, moist skin
Fine tremor
Palmar erythema
Thin hair
Lid lag
Lid retration
Goitre

Question 18

Summarise treatment for hyperthyroidism. (4)

Answer 18

1. Beta blockers
2. Thionamides
3. Radioiodine (131I)
4. Thyroidectomy)

Question 19

List 4 risk factors for Graves’ disease.

Answer 19

Other autoimmune disease
Genetic susceptibility
Environmental exposure (e.g. iodine)
Immune modulating treatment (e.g. interferon, alemtuzemab)

Question 20

What do you call iodine induced hyperthyroidism?

Answer 20

Jod Basedow phenomenon