9. Thyroid disorders

Question 1

What is hyperthyrodism

Answer 1

Characterised by a high level of thyroid hromones (T3/T4 and low TSH)

This affects
1. Metabolic rate
2. heart rate
3. digestive functions

Question 2

Hyperthyroidism symptoms

Answer 2

• Weight loss
• heat intolerance
• tachycardia
• bulging eyes
• Goitre (lump at the front of the neck)
• Diarrhoea

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Question 3

Hyperthyroidism diagnosis

Answer 3

High levels of T3/T4 & Low TSH due to the negative feedback relationship

Question 4

Carbimazole and propylthiouracil mechanism of action

Answer 4

Interfere with the synthesis of thyroid hormones T4 and T4 to lower thyroid hormone levels

Question 5

Hyperthyroidism treatment

Answer 5

1st line: carbimazole (+ contraception if patient is of child bearing age)
Regimen can be based on thryroid function tests as a titration regimen OR block and replace regimen where fixed high doses of carbimazole and levothryoxine are given

If patient is pregnant or trying to conceive:
1st line: propylthiouracil as carbimazole is teratogenic

Question 6

Carbimazole side effects

Answer 6

• Blood dycrasias as low white blood cell count: patients must report signs of infections or fever, or sore throat, mouth ulcers, bruising and bleeding
• acute pancreatitis - if occurs patient must stop immediately
• Rashes and itching - can be managed with antihistamine. If intolerable, propylthiouracil can be suggested alternatively

Question 7

Propylthiouracil side effects

Answer 7

Hepatoxicity: persistent vomiting, abdominal pain, jaundice, dark urine

Discontinue if liver enzymes are 3x as high (ALT and AST)

Question 8

Hypothyroidism and symptoms

Answer 8

Characterised by a low level of T3/T4 and High TSH

symptoms:
* cold intolerance
* weight gain
* bradycardia
* constipation

symptoms of hyperthyroidism is opposite to hypothyroidim

Question 9

Hypothyroidism diagnosis

Answer 9

A blood test will reveal low levels of T3/T4 and High TSH.
As pituitary gland recognises there is insufficient thryoid hormones, so responds by releasing more TSH, to stimulate more thryoid production out of the thryoid glands

Common drugs that cause hypothyroidism:
Lithium, amiodarone

Question 10

Hypothyroidism treatment

Answer 10

Are synthetic thyroid hormones used to replenish thyroid hormones

1st line: Levothyroxine
Liothyronine treats more severe hypothyroidism or if a rapid response is needed

Question 11

Levothyroxine counselling

Answer 11

Should be take at least 30 minutes before breakfast, caffeine or other medication as it can reduce absorption.

Have a 2-hour gap with medications such as bisphosphonates that have their own counselling requirements

Leave a 4-hour gap between anatacids, calcium and iron

Question 12

Thyroid hormone side effects

Answer 12

Thyrotoxic side effects:
Increased heart rate, insomnia, anxiety, tremors, anginal pain.
Caution in CVD, diabetes (as thryoid hormones raise blood glucose levels so the dose of insulin or antidiabetic drugs may needs to be increased).

If thyrotoxic side effects occur reduce the dose, or stop the dose and continue once side effects have resolved

Question 13

Swicthing Levothyroxine brands

Answer 13

20-25mcg liothyronine = 100mcg levothyroxine
Must have a UK license to be able to switch between brands

When changing to a different tablet of levothyroxine, a TFT should be conducted, if patient is experiencing symptoms related to thyroid dysfunction:

1. Prescribe a levothyroxine tablet known to be well tolerated by patient
2. If symmptoms or poor control continue even when patient is adhering to the new tablet = consider an oral solution

Question 14

What is graves disease and what is first Line treatment

Answer 14

A common cause of hyperthyroidism

radioactive iodine