1b Hyperthyroidism

Question 1

Where is the thyroxine stored?

Answer 1

In the thyroid follicle which contains thyroglobulin

Question 2

Describe the HPT axis

Answer 2

1. Hypothlamus releases TRH
2. This acts on the thyrotrophs in the pituitary to release TSH
3. They act on thyroid to release T3 and T4
4. These hormones then work by negative feedback to inhibit the pituitary and the hypothalamus at each level

Question 3

What level of TSH will you find a patient with primary hypothyroidism, where the thyroid gland has been destroyed by the immune system?

Answer 3

high TSH

Question 4

How do you control thyroid replacement?

Answer 4

Give thyroxine medication
Increase the dose until the TSH falls to normal

Question 5

Describe the typical appearance of the thyroid gland in Graves disease

Answer 5

Smooth, diffuse, symmetrical enlargement of the thyroid gland, pain free when swallowing

Question 6

What are the common symptoms of Grave’s Disease?

Answer 6

Pretibital Myxoedema
Exothphalmos
Weight loss
Tremor
Palpitations
Rapid pulse
Agitation
Smooth Goitre

Question 7

What causes exophthalmos of the eye?

Answer 7

The antibodies bind to the muscles behind the eye and cause it to pop out the socket

Question 8

What causes pretibial myxoedema?

Answer 8

When other antibodies bind to the muscles in the shin and cause hypertrophy of the skin - non pitting swelling

Question 9

Describe the uptake of radioiodine?

Answer 9

Uniform

Question 10

What is toxic nodular goitre disease?

Answer 10

A benign adenoma which is overactive and making too much thyroxine

Question 11

What is seen in patients with toxic nodular goitre disease?

Answer 11

Unsymmetrical enlargement of the thyroid, with a single hot nodule seen on a radioiodine scan

Question 12

What is the effect of thyroxine on the sympathetic nervous system?

Answer 12

Thyroxine sensitizes the beta adrenoreceptors to the ambient levels of adrenaline, so there is sympathetic activation

Question 13

What symptoms are seen in hyperthyroidism due to the sympathetic activation?

Answer 13

Tachycadia, palpitations, tremor and lid lag

Question 14

What causes lid lag?

Answer 14

This is inability of the eyelid to close properly due to the excess adrenaline which is holding the eyelid open

Question 15

What are the features of a thyroid storm?

Answer 15

Fever
Accelerated tachycadia
Cardiac Failure
Psychosis
Liver failure

Question 16

What are the three options of treatment for hyperthyroidism/

Answer 16

Drugs
Radiotherapy
Surgery

Question 17

What are the three drugs used to control T4 levels in hyperthyroidism?

Answer 17

Thionamides
Potassium Iodide
Radioiodide

Question 18

What drugs are used for symptomatic control in hyperthyroidism?

Answer 18

Non-specific Beta blockers to reduce heart rate, tremors

Question 19

How do thionamides work?

Answer 19

They inhibit thyroperoxidase synthesis therefore thyroxine cannot be made

Question 20

What is the name of the most common thionamide?

Answer 20

Carbimazole

Question 21

What is a good non specific beta blocker which is used?

Answer 21

Propranolol

Question 22

What are the unwanted actions of thionamides?

Answer 22

agranulocytosis and rashes

Question 23

What is agranulocytosis?

Answer 23

a reduction in neutrophils - patients asked if they have a sore throat as the susceptibility to adaptive infections is higher

Question 24

what is the role of beta blockers in thyrotoxicosis?

Answer 24

It takes several weeks for ATDs (anti thyroid drugs) to have clinical effects due to the stored thyroxine in the follicle for up to a month), therefore beta blockers work in the interim

Question 25

When is KI given as a treatment?

Answer 25

prepare hyperthyroid patient for surgery
thyroid storm

Question 26

How does KI work as a treatment for hyperthyroidism?

Answer 26

Inhibition of thyroid hormone synthesis due to the Wolff-Chaikoff effect. - the KI inhibits the iodination of TG and therefore inhibits hydrogen peroxidase production

Question 27

Why is KI given to hyperthyroid surgery patients?

Answer 27

The gland becomes less vascular and undergoes ATROPHY therefore becomes easier to operate on

Question 28

What are the risks of thyroid surgery?

Answer 28

Risk of voice change due to damage to the recurrent laryngeal nerve

Risk of losing parathyroid glands

Question 29

Which patients cannot use radioiodine?

Answer 29

Pregnant women, and people with kids, people around children as they become radioactive

Question 30

Why is pertechnetate used instead of radioiodine?

Answer 30

Cheaper

Question 31

what are the names of the two anti-thyroid drugs?

Answer 31

Carbimazole
Propylthiouracil (PTU)

Question 32

What is viral thyroditis?

Answer 32

When a virus infects the thyroid gland and overrules thyroxine production and results in hyperthyroidism as all the thyroxine which is stored in the follicles is released

Question 33

How to differentiate between viral thyroditis and Graves?

Answer 33

Viral = painful when swallowing

Question 34

What are the symptoms of viral thyroditis?

Answer 34

Thyroid visibly enlarged on one side
Dysphagia (difficulty swallowing), Odynophagia (pain when swallowing)
Pain radiating to the ear

Question 35

What is seen on a radioiodine scan of the thyroid in a patient with viral thyroditis?

Answer 35

Nothing as there is no iodine uptake

Question 36

What is seen when monitoring a patient with viral thyroditis over a three month period?

Answer 36

First hyperthyroidism as all the stored thyroxine is released and TSH drops

Then hypothyroidism as the stored thyroxine is released

After a further month the disease is resolved

Question 37

How is postpartum thyroditis different to viral thyroditis?

Answer 37

No pain and only occurs after pregnancy as the immune system is moduled during pregnancy