Hyperthyroidism

Question 1

What is hyperthyroidism?

Answer 1

pathologically increased thyroid hormone production + secretion by the thyroid gland

Question 2

What is thyrotoxicosis?

Answer 2

Clinical manifestation of excess circulating thyroid hormones due to any cause

Question 3

List 6 causes of thyrotoxicosis

Answer 3

Graves’ disease (most common)
Toxic multi nodular goitre
Acute phase of de Quervain’s thyroiditis
Acute phase of postpartum thyroiditis
Acute phase of Hashimoto’s thyroiditis
Amiodarone

Question 4

What is primary hyperthyroidism?

Answer 4

Thyrotoxicosis caused by abnormality of the thyroid gland e.g. Graves’ disease or nodular goitre

Question 5

What are the 2 subtypes of primary hyperthyroidism?

Answer 5

Overt: TSH < normal, T3/T4 > normal

Subclinical: TSH < normal, T3/T4 normal

Question 6

List 4 risk factors for development of hyperthyroidism

Answer 6

F > M
FH
Smoking
Other AI disease e.g. T1DM

Question 7

What is Graves’ disease?

Answer 7

AI disorder mediated by TSH receptor antibodies
TRAbs timulate TSH receptor, leading to thyroid hyperplasia + unregulated excessive production + secretion of thyroid hormone

Question 8

List 3 signs specific to Graves’ and not seen in other causes of thyrotoxicosis

Answer 8

Eye signs (30%)
Pretibial myxoedema
Thyroid acropachy

Question 9

What eye signs may be seen in Graves’ disease?

Answer 9

Exophthalmos
Ophthalmoplegia
Conjunctival oedema
Optic disc swelling
Inability to close eyelids may lead to sore, dry eyes (risks exposure Keratopathy)

Question 10

What is thyroid acropachy?

Answer 10

Triad of:
Digital clubbing
Soft tissue swelling of hands + feet
Periosteal new bone formation

Question 11

What is the most important modifiable risk factor for thyroid eye disease in Graves’ disease?

Answer 11

Smoking

Question 12

How does radio iodine affect thyroid eye disease?

Answer 12

Increases inflammatory Sx of thyroid eye disease

Question 13

Which antibodies may be found in Graves’ disease?

Answer 13

TSH receptor stimulating antibodies (90%)
Anti-thyroid peroxidase antibodies (75%)

Question 14

Describe Thyroid Scintigraphy in Graves’ disease

Answer 14

Diffuse, homogenous, increased uptake of radioactive iodine

Question 15

Describe initial management of Graves’ disease

Answer 15

Propanolol to block adrenergic effects (palpitations, tremor, tachycardia)
Refer
Specialists: ATD e.g. Carbimazole (if Sx not controlled by propranolol)

Question 16

What are anti-thyroid drugs aka? Give 2 examples

Answer 16

Thionamides
Carbimazole
Propylthiouracil

Question 17

Describe the titration regime of carbimazole for Graves’ disease

Answer 17

Start Carbimazole 40mg
Reduce gradually to maintain euthyroidism
Continued for ~12-18 months

Question 18

What is the ‘block and replace’ regime of Carbimazole for Graves’ disease?

Answer 18

Start Carbimazole 40mg
Add Thyroxine when patient is euthyroid
Tx lasts ~6-9 months

Question 19

Compare the regimes of carbimazole use in Graves’ disease

Answer 19

ATD titration regime suffer fewer side-effects than those on block-and-replace regime

Question 20

What is the main adverse effect of carbimazole?

Answer 20

Agranulocytosis

Question 21

What is the main risk of propylthiouracil?

Answer 21

Severe liver injury

Question 22

When is propylthiouracil used first line in Graves’ disease?

Answer 22

Pre-pregnancy/ 1st Trimester
(Carbimazole a/w congenital abnormalities)

Question 23

When is radio-iodine used in Graves’ disease?

Answer 23

Relapse following ATD therapy
Resistance to primary ATD Tx

Question 24

What are the contraindications to radio-iodine for Graves’ disease?

Answer 24

Pregnancy (+ avoid for 4-6 months following Tx)
Age < 16y .

Relative CI: Thyroid eye disease- may worsen the condition

Question 25

What proportion of patients receiving radio-iodine for Graves' become hypothyroid?

Answer 25

Depends on dose Majority require thyroxine supplementation after 5y

Question 26

Describe management of thyroid eye disease

Answer 26

TOP lubricants: help prevent corneal inflammation caused by exposure Steroids: Prednisolone Orbita irradiation Rehabilitative surgery

Question 27

For patients with established thyroid eye disease, which 6 features indicate the need for urgent review by ophthalmology?

Answer 27

Unexplained deterioration in vision Awareness of change in intensity or quality of colour vision in 1/ both eyes Hx of eye suddenly 'popping out' (globe subluxation) Obvious corneal opacity Cornea still visible when eyelids are closed Disc swelling

Question 28

What is Toxic Multinodular Goitre?

Answer 28

Thyroid gland containing a number of autonomously functioning thyroid nodules resulting in hyperthyroidism (2nd most common cause)

Question 29

Describe nuclear scintigraphy in Toxic multi nodular goitre

Answer 29

Patchy uptake.

Question 30

Describe management of Toxic multinodular goitre

Answer 30

Radioiodine therapy

Question 31

What is Thyrotoxicosis without hyperthyroidism?

Answer 31

Thyrotoxicosis without thyroid gland overactivity Usually transient

Question 32

List 3 causes of thyrotoxicosis without hyperthyroidism

Answer 32

Postpartum thyroiditis Subacute (de Quervain's) thyroiditis Drug induced: Amiodarone induced thyrotoxicosis

Question 33

List features of thyrotoxicosis by system

Answer 33

General: WL, 'Manic', restlessness, Heat intolerance Cardiac: Palpitations, tachycardia high-output HF (elderly), reversible cardiomyopathy (rare) Skin: Sweating, Pretibial myxoedema, Thyroid acropachy GI: Increased appetite, Diarrhoea Gynae: Oligomenorrhea, sub fertility Neurological: Anxiety, Tremor

Question 34

What is pretibial myxoedema?

Answer 34

Erythematous, oedematous lesions above the lateral malleoli

Question 35

What is thyroid storm?

Answer 35

Rare but life-threatening complication of thyrotoxicosis. Typically seen in those with established thyrotoxicosis, rarely seen as presenting feature

Question 36

List 4 precipitating events of thyroid storm

Answer 36

Thyroid or non-thyroidal surgery Trauma Infection Acute iodine load e.g. CT contrast media

Question 37

List 7 clinical features of thyroid storm

Answer 37

Fever > 38.5ºC Tachycardia Confusion + agitation N+V HTN Heart failure Abnormal LFTs +/or jaundice

Question 38

Describe management of thyroid storm

Answer 38

High dose Anti-thyroid drugs: Carbimazole or propylthiouracil + Hydrocortisone IV (reduce peripheral conversion of T4 to the more active T3) + B-blockers: IV propranolol + Lugol's iodine + Symptomatic Tx e.g. paracetamol Tx of underlying precipitating event

Question 39

Why may colestyramine be considered in management of thyroid storm?

Answer 39

= bile acid-sequestering agent Reduces enterohepatic circulation of thyroid hormones.