Hyperthyroidism

Question 1

What does TSH do?

Answer 1

Activates the uptake o iodine by the thyroid gland

Stimulates the production of thyroxine

Question 2

How much Thyroxine do you store at once?

Answer 2

Enough for a whole month

So you can release it when it is required

Question 3

How can thyroxine enter the blood stream from the thyroid gland?

Answer 3

Proteolytic enzyme forms a whole allowing thyroxine to enter the blood stream

Question 4

What makes TRH?

Answer 4

Hypothalamus

Question 5

What effects do T3 and T4 have on the pituitary and hypothalamus?

Answer 5

Negative

Question 6

What level of TSH will you find in a patient wit primary hypothyroidism?

Answer 6

High TSH

Pituitary hormone tries to stimulate the production of Thyroxine since levels are low

Question 7

How do we treat primary hypothyroidism?

Answer 7

Replacement by tablet
Increase does until TSH is normal
Will have to take for life
Once daily

Question 8

What is the half-life of thyroxine?

Answer 8

10 days

Question 9

Why is the half-life of thyroxine significant?

Answer 9

You can make up for missing a dose by taking a double dose

Question 10

What is Graves’ disease?

Answer 10

Autoimmune
Antibodies bind to and stimulate the TSH receptor in the thyroid
Causes goitre (smooth) and hyperthyroidism

Question 11

Give some symptoms of Graves

Answer 11

Perspiration
Facial flushing
Muscle wasting
Shortness of breath
Breast enlargement
Expophthalmos
Goitre 
Palpitaiton
Increase appetite
Tremor
Localised myxoedema
Oligomenorrhea/Amenorrhea

Question 12

Why do you get exophthalmos?

Answer 12

Antibodies bind to growth factor receptor antibodies on muscles
at the back of the eye

Question 13

What is pretibial myxoedema?

Answer 13

Swelling on the shins of patients with graves disease: growth of soft tissue

Question 14

What is myxoedema?

Answer 14

Auto-immune hypothyroidism

Question 15

What is an iodine uptake scan?

Answer 15

Give radioactive iodine
Goes into thyroid
Can show thyroid size and uniform radio iodine uptake
Very black

Question 16

What is Plummer’s disease?

Answer 16

Toxic nodular goitre
Not immune
Benign adenoma that is overactive at making thyroxine

Question 17

How do you differentiate between Graves’ and Plummer’s?

Answer 17

No exophthalmos
NO pretibial myxoedema
Different iodine uptake scans (one side and more at salivary glands)

Question 18

What happens in Plummer’s disease?

Answer 18

Thyroid atrophies and shrinks away

Tumor is overactive

Question 19

What can Plummer’s disease be known as?

Answer 19

Toxic nodular goitre

Single hot nodule

Question 20

What are the effects of thyroxine on the sympathetic nervous system?

Answer 20

Sensitises beta adrenoreceptors to ambient levels of adrenaline and nor adrenaline

‘a bit of adrenaline goes a long way’

Question 21

What does the adrenaline cause?

Answer 21

The minute they try to be active they get tachycardia, palpitation, tremor in hands and lid lag

Question 22

What is lid lag?

Answer 22

Ask the patient to follow your finger

Eyelids are held back by adrenaline

Question 23

What did the patient present with?

Answer 23

Weight loss despite increase appetite 
breathlessness
Palpitations
Tachycardia
Sweating
Heat intolerance
Diarrhoea
Lid lag and other sympathetic features

Question 24

What is a thyroid storm?

Answer 24

Medical emergency: 50% mortality untreated

Blood results confirm hyperthyroidism

Question 25

What are symptoms of a thyroid storm?

Answer 25

``` Hyperpyrexia > 41 Accelerated tachycardia / arrhythmia cardiac failure delirium / frank pschosis haptocellular dysfunction ; jaundice ```

Question 26

What are treatment options for those with hyperthyroidism?

Answer 26

Surgery (thyroidectomy) Radioiodine Drugs

Question 27

What classes of drugs are used to treat hyperthyroidism?

Answer 27

1. The thionamides (thiourylenes; anti-thyroid drugs) - propylthiouracil (PTU) - carbimazole (CBZ) 2. Potassium Iodide 3. Radioiodine 4. β-blockers

Question 28

What is the mechanism of action of thionamide?

Answer 28

Inhibits TPO Blocks synthesis of T3/T4 Due to stores they don't get better for a month

Question 29

Why do you give the patient a beta-blocker with thionamide treatment?

Answer 29

Make them feel better whilst waiting for the thionamide to work

Question 30

What are the side effects of thionamide treatment?

Answer 30

Agranulocytosis (usually reduction in neutrophils) - rare and reversible on withdrawal of drug. rashes (relatively common)

Question 31

What is the role of beta blockers in treating hyperthyroidism?

Answer 31

Several weeks for ATDs to have clinical effects e.g reduced tremor, slower heart rate, less anxiety NON-selective (ie b1 & b2) b blocker eg propranolol achieves these effects in the interim

Question 32

When do you give potassium iodide?

Answer 32

preparation of hyperthyroid patients for surgery severe thyrotoxic crisis (thyroid storm)

Question 33

What are the problems with thyroid surgery?

Answer 33

Risk of voice change Risk of also losing parathyroid glands Scar Anaesthetic

Question 34

How do you give radioiodine?

Answer 34

Swallow a capsule containing about 370 MBq (10 mCi) of the isotope I (131) Contraindicated in pregnancy Need to avoid children and pregnant mums for a few days For scans only (not treatment), 99-Tc pertechnetate is an option.

Question 35

Why must you isolate if you are taking radioiodine?

Answer 35

You emit radiation for 20 days Must stay away from anyone who could be pregnant

Question 36

Summarise the treatment options?

Answer 36

Drugs: Beta blockade is VERY IMPORTANT propranolol Anti thyroid drugs : Carbimazole Propylthiouracil Surgery Radioiodide

Question 37

What is viral thyroiditis?

Answer 37

Painful dysphagia Hyperthyroidism Pyrexia Thyroid gland is visibly enlarged

Question 38

What happened in viral thyroiditis?

Answer 38

Stop iodine uptake and the thyroid makes more virus instead NO uptake of iodine All stored thyroxine released Present with typical features of hyperthyroidism 4 weeks later when the stored thyroxine is exhausted you become hypothyroid

Question 39

Summaries the features of Viral (de Quervains) thyroiditis

Answer 39

``` Neck becomes painful All stored thyroxine released Free T4 levels rise TSH levels drop 1 month hyperthyroidism But NO new thyroxine is being synthesised ``` Patient becomes hypothyroid – gland stops making thyroxine and just replicates virus Hypothyroidism lasts a second month After 3 months, there is slow recovery

Question 40

What is postpartum thyroiditis?

Answer 40

Similar to viral but no pain only occurs after pregnancy Immune system modulated during pregnancy