Thyrotoxicosis

Question 1

Define hyperthyroidism and thyrotoxicosis

Answer 1

Thyrotoxicosis is the clinical manifestation of excess thyroid hormone action at the tissue level due to inappropriately high circulating thyroid hormone concentrations.

Hyperthyroidism is a subset of thyrotoxicosis, referring specifically to excess thyroid hormone synthesis and secretion by the thyroid gland.

Question 2

Aetiology of thyrotoxicosis

Answer 2

Hyperthyroidism (graves, toxic multinodular goitre, toxic adenoma, TSH-secreting pituitary tumour, drugs, choriocarcinoma)
Thyroiditis: post-partum, Viral (de Quervain’s)

Question 3

Symptoms of thyroid storm

Answer 3

Fever
Palpitations
Tremor
Nausea and vomiting
Abdominal pain
Restlessness
Reduced level of consciousness
Confusion/agitation
Seizures
Coma

Question 4

Signs of thyroid storm on examination

Answer 4

General
- Hyperpyrexia
- Underweight, restless, irritable, sweating
- Tremor , warm, moist, rapid, irregular pulse, onycholysis, palmar erythema
- Wide pulse pressure
- Proximal muscle weakness, hyper-reflexia
- Clubbing
- Pretibial myxoedema
Head and neck
- Lid retraction and lid lag, proptosis, ophthalmoplegia, optic nerve atrophy
- Goitre or bruit

Question 5

Investigations for thyroid storm

Answer 5

TFTs: raised T4/T3, low TSH (unless secondary)

US thyroid: ?nodule
Technetium uptake

Question 6

What can a technetium uptake scan of the thyroid show

Answer 6

Graves’: diffuse uptake
Toxic multinodular goitre: Multinodular gland with single hot nodule
Thyroid cancer: diffuse uptake with single cold nodule
De Quervain’s: no uptake

Question 7

Management for thyroid storm

Answer 7

Supportive: fluid balance, cool down (paracetamol, dantrolene), beta block (80mg propranolol 3x a day), ?infection, chlorpromazine
Medical: Carbimazole 60mg
Surgical: must be euthyroid → Lugol’s iodine/potassium iodide OR propranolol → can operate 5 days later

1. Propranolol 60mg IV QDS
   a. ± digoxin
   b. Diltiazem if beta blockers CI
2. Carbimazole 15-25mg PO QDS (inhibits TPO)
3. Hydrocortisone 100mg IV QDS OR dexamethasone 2mg PO QDS
4. Treat precipitating factor e.g. abx, cooling, fluids

Ongoing management after first carbimazole dose:
4 hours: propranolol and Lugol’s iodine for 10 days (0.3mL diluted in water, TDS)
5 days: reduce carbimazole to 15mg, TDS, PO
10 days: stop propranolol and iodine; adjust carbimazole

Question 8

What is a thyroid storm and what causes it

Answer 8

Storm
Acute and life-threatening presentation of thyrotoxicosis often caused by precipitating event:
- Recent thyroid surgery
- Radioiodine
- Infection
- MI
- Trauma