hyperthyroidism and thyrotoxicosis

Question 1

Thyrotoxicosis

Answer 1

State when tissues are exposed to excess thyroid hormone

Question 2

Primary Hyperthyroidism

Answer 2

Free T3/T4 high

TSH low

Question 3

Secondary hyperthyroidism

Answer 3

Free T3/T4 high 
TSH high (or 'normal')

Question 4

Hyperthyroidism Aetiology

Answer 4

Excessive thyroid stimulation

• Graves disease
• Hashitoxicosis
• Thyrotropinoma
• Thyroid cancer
• Choriocarcinoma

Thyroid nodules with autonomous function

• toxic solitary nodule
• Toxic multi nodular goitre

Question 5

Thyrotoxicosis Aetiology

Answer 5

Causes of Hyperthyroidism

• Excessive thyroid stimulation
• Thyroid nodules with autonomous function

Thyroid inflammation (thyroiditis)

• Subacute (de Quervains)
• Post partum
• Drug induced

Exogenous Thyroid Hormones

• Over treatment with levothyroxine
• Thyrotoxicosis factitia

Ectopic Thyroid tissue

• Metastatic thyroid carcinoma
• Struma Ovarii

Question 6

Thyrotoxicosis Signs and Symptoms

Answer 6

Cardiac

• Palpitation (AF)
• Cardiac failure (very rare0

Sympathetic

• Tremor
• Sweating

CNS

• Anxiety
• nervousness
• Irritability
• sleep disturbance

GI
-frequent, loose bowel movements

Vision

• liquid retraction
• double vision (diplopia)
• Proptosis (–> Graves)

Hair and skin

• brittle, thin hair
• Rapid fingernail growth

Reproductive
- Menstrual cycle changes (lighter bleeding and less frequency)

Muscle Weakness (esp, thighs and upper arms)

metabolism

• Increased appetite
• unintentional weight loss

Thermogenesis
-Intolerance to heat

Question 7

Graves Disease Aetiology & Epidemiology

Answer 7

Interacting susceptibility genes plus environmental factors

Younger (20-50 years)

Smoking important

Question 8

Graves Disease; Laboratory Investigations

Answer 8

Decreased TSH

Increased fT3/T4

hypercalcaemia and increase Alk Phos.
- increased bone turnover: Osteoporosis

Leucopenia (decreased WCC)

TSH receptor antibody (TRA b)

Question 9

Specific Graves Clinical Signs

Answer 9

pretibial Myxoedema 
Thyroid acropachy 
Smooth goitre 
Thyroid bruit
-Associated only with large goitres 

Graves Eye Disease

Question 10

Graves Eye Disease

Answer 10

Thyroid Eye Disease

Occurs in ~20% of patients with Graves

Associated with smoking

TRAb driven pathology

Treatment

• Mild: Topical
• Severe; Steroids, surgery

Question 11

Nodular Thyroid Disease Presentation

Answer 11

Older patients. More insidious onset

Thyroid may feel nodular 
Asymmetrical goitre (smooth in graves)

Question 12

Nodular Thyroid Disease Investigation

Answer 12

Increased fT3/T4
Decreased TSH

Antibody negative.

Scintigraphy: high uptake

Thyroid Ultrasound

Question 13

Thyroid storm

Answer 13

Crisis
- Medical Emergency

Severe hypothyroidism

Question 14

Thyroid storm features

Answer 14

Respiratory and cardiac collapse
Hyperthermia
Exaggerated reflexes

Question 15

Thyroid Storm Treatment

Answer 15

may require mechanical ventilation

Lugols. iodine 
Glucocorticoids 
PTU
B-blocker
FLuids
Monitoring

Question 16

Hyperthyroidism Treatment

Answer 16

Antithyroid drugs (ATDs)
Beta-blockers
Radioiodine
Thyroidectomy

Question 17

Antithyroid Drugs (ATDs) Mechanism

Answer 17

Inhibition of thyroid peroxidase (TPO) thereby blocking thyroid hormone synthesis

Question 18

ATD examples

Answer 18

Carbimazole

• 1st line (once daily dosing)
• Risk off aplasia cutis in early pregnancy

Propylthiouracil
-1st line in first trimester pregnancy

Question 19

ATD Side Effects

Answer 19

Generally well tolerated

Allergic Type Reactions (1-5%)

Liver

• Increased risk of cholestatic jaundice
• Increased liver enzymes
• Fulminant hepatic failure

Agranulocytosis (0.1-0.5%)

• Important to warn patient verbally and in writing to STOP drug and urgent FBC checked in event of fever, oral ulcer or oropharyngeal infection
• ATDs cannot be used again
• Risk highest in first 6 weeks

Question 20

beta- blockers mechanism and use

Answer 20

B-adrenoreceptor blockage, reduced activity of sympathetic nervous system

Propranolol is drug of choice

Useful for immediate symptomatic relief of thyrotoxic symptoms

Question 21

Radioiodine

Answer 21

1st line treatment in

• Relapsed Graves disease
• Nodular Thyroid disease

Question 22

Radioiodine contraindications

Answer 22

Contraindicated in pregnancy

Relatively contraindicated in active thyroid eye disease (can be used with steroid cover)

High risk of hypothyroidism in Graves

Question 23

Thyroidectomy

Answer 23

useful if radio iodine contraindicated

Will leave a scar

Surgical/ anaesthetic risks

• recurrent laryngeal nerve palsy
• hypothyroidism
• hypoparathyroidism