1b Hyperthyroidism Flashcards

1
Q

Where is the thyroxine stored?

A

In the thyroid follicle which contains thyroglobulin

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2
Q

Describe the HPT axis

A
  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
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3
Q

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

A

`high TSH

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4
Q

How do you control thyroid replacement?

A

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

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5
Q

Describe the typical appears of the thyroid gland in Graves disease

A

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

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6
Q

What are the common symptoms of Grave’s Disease?

A

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

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7
Q

What causes exophthalmos of the eye?

A

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

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8
Q

What causes pretibial myxoedema?

A

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

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9
Q

Describe the uptake of radioiodine?

A

Uniform

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10
Q

What is toxic nodular goitre disese?

A

A benign adenoma which is overactive and making too much thyroxine

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11
Q

What is seen in patients with toxic nodular goitre disease?

A

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

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12
Q

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

A

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

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13
Q

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

A

Tachycadia, palpitations, tremor and lid lag

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14
Q

What causes lid lag?

A

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

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15
Q

What are the features of a thyroid storm?

A

Fever
Accelerated tachycadia
Cardiac Failure
Psychosis
Liver failure

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16
Q

What are the three options of treatment for hyperthyroidism/

A

Drugs
Radiotherapy
Surgery

17
Q

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

A

Thionamides
Potassium Iodide
Radioiodide

18
Q

What drugs are used for symptomatic control in hyperthyroidism?

A

NOn-specific Beta blockers to reduce heart rate, tremors

19
Q

How do thionamides work?

A

They inhibit thyroperoxidase synthesis therefore thyroxine cannot be made

20
Q

What is the name of the most common thionamide?

A

Carbimazole

21
Q

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

A

Propranolol

22
Q

What are the unwanted actions of thionamides?

A

agranulocytosis and rashes

23
Q

What is agranulocytosis?

A

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

24
Q

what is the role of beta blockers in thyrotoxicosis?

A

It takes several weeks for ATDs to have clinical effects \9due to the stored thyroxine in the follicle for up to a month), therefore beta blockers work in the interim

25
Q

When is KI givn as a treatment?

A

prepare hyperthyroid patient for surgery
thyroid storm

26
Q

How does KI work as a treatment for hyperthyroidism?

A

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

27
Q

Why is KI given to hyperthyroid surgery patients?

A

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

28
Q

What are the risks of thyroid surgery?

A

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

Risk of losing parathyroid glands

29
Q

Which patients cannot use radioiodine?

A

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

30
Q

Why is pertechnetate used instead of radioiodine?

A

Cheaper

31
Q

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

A

Carbimazole
Propylthiouracil

32
Q

What is viral thyroditis?

A

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

33
Q

How to differentiate between viral thyroditis and Graves?

A

Viral = painful when swallowing

34
Q

What are the symptoms of viral thyroditis?

A

Thyroid visibly enlarged on one side
Dysphagia, Pain radiating to the ear

35
Q

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

A

Nothing as there is no iodine uptake

36
Q

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

A

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

37
Q

How is postpartum thyroditis different to viral thyroditis?

A

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