Hyperthyroidism

Question 1

Definition

- Main causes (4)

Answer 1

Excess production of thyroid hormones: T3/T4.

Main causes
- Autoimmune. Activation of TSH receptors via auto-antibodies (Graves).

• Toxic thyroid adenoma: producing excess thyroid hormone.
• Toxic multinodular goiter: excess thyroid hormone production from multiple nodules without TSH stimulation.
• Tyroiditis

Question 2

Hyperthyroidism symptoms (6)

Answer 2

Palpitations

Heat intolerance

Diarrhoea

Unintentional weight loss despite increase in food intake.

Insomnia

Irregular menstrual cycles
- Oligomenorrhea

Question 3

Hyperthyroidism signs (7)

Answer 3

Tachycardia

Tremors

Arrhythmias
- Esp AF

Graves eye disease
- proptosis, opthalomyopathy

Goitre
- Bruit= graves

Hyperhydrosis

Pretibial myxedema (Graves

Question 4

Thyroid storm

• Definition
• Causes
• Treatment

Answer 4

Syndrome caused by excess thyroid hormone production:

• High fever >40
• Tachycardia
• Arrhythmia
• Hypertension
• Vomiting and diarrhoea

Causes

• Illness whilst having mild untreated hyperthyroidism
• Stopped/ ineffective treatment for hyperthyroisim

Treatment

• Inorganic iodine
• Antithyroid drugs: propylthiouracil/ methiamazole
• Beta-blockers for symptom control

Question 5

Graves disease

• Cause
• Specific signs
• Treatment

Answer 5

Autoimmune condition, caused by autoantibodies created to stimulate TSH receptors in the thyroid.
- Most common cause of hyperthyroidism.

Specific signs

• Graves opthalmopathy: lid retraction, eye dryness, proptosis
• Goitre with a bruit
• Pretibial myxedema

Treatment

• Antithyroid drugs: carbimazole, propylthiouracil.
• Radioiodine
• Thyroidectomy

Question 6

Thyroiditis

• definition
• Specific signs

Answer 6

Inflammation of the thyroid
- Can be due to immunological attack

Causes

• Associated with IgG4 systemic disease (Riedel’s)
• Infection
• Hashimoto’s
• Postpartum
• Drug/ radiation induced

Signs
- Can have hypothyroid or hyperthyroid signs

Question 7

Diagnosis of hyperthyroidism

Answer 7

History

• Sudden onset?
• Progression of symptoms
• Family history
• New drug?

Examination
- Signs of hyperthyroidism

Blood test

• LFT: increased free T3/4, decreased TSH. Unless very very rarely TSH releasing tumour.

TSH receptor antibody= Graves

ECG
- Arrhythmias

Imaging

• Thyroid isotope scan. Looking at the uptake can determine if activity is diffuse or nodular.
• Thyroid ultrasound: detects nodules

Question 8

Carbimazole

• Description/ Mechanism
• Dosing/ administration
• Side effects

Answer 8

Antithyroid drug

• Pro-drug that converts into methimazole, which inhibits thyroid peroxidase.
• Reduces T3 and T4 production

Administration

• PO
• Start on 15-40mg OD until euthyroid (4-8 weeks)
• Reduce to 5-15mg PO
• Given for 12-18 months.

Side effects

• Mone marrow suppression
• Teratogenic
• Acute pancreatitis

Question 9

Propylthiouracil

• Description/ Mechanism
• Dosing/ administration
• Side effects

Answer 9

Anti thyroid drug

• Esp for graves and toxic multinodular goitre
• Second line to radioactive iodine/ surgery/ carbimazole
• Inhibts thyroperoxidase, preventing formation of T4.
• Prevtns conversion of T4 to T3 in tissue.

Administration

• Loading dose: 200-400mg until euthyroid
• Maintainence dose= 50-150mg

Side effects

• Bone marrow suppression
• Skin rashes
• Skin pigmentation
• Caution in pregnancy

Question 10

Thyroid eye disease

• Features
• management

Answer 10

Symptoms

• eye discomfort/ grittiness
• Diplopia
• photophobia

Signs

• Protruding eyes/ proptosis
• Conjuctival oedema
• Loss of colour vision
• Opthalmopegia

Management

• symptomatic: sunglasses, avoid dust, elevat bed when sleeping
• High dose steroids if severe
• surgical decompression
• Orbital radiotherapy (opthalmoplegia)
• Infliximab