Thyroid conditions

Question 1

What are the two forms of the Thyroid hormone?

Answer 1

T3 and T4

Question 2

What is T3?

Answer 2

Tri-iodothyronine

Question 3

What is T4?

Answer 3

Thyroxine

Question 4

What is TSH?

Answer 4

Thyroid Stimulating Hormone

Question 5

Where is TSH released from?

Answer 5

The Anterior Pituitary gland

Question 6

What is Hyperthyroidism characterised by?

Answer 6

LOW TSH levels and HIGH T3 and T4 levels

Question 7

Why does Hyperthyroidism occur?

Answer 7

Too much T3 and T4 being produced by the thyroid gland and the negative feedback loop causes the Anterior Pituitary gland to stop production of TSH.

Question 8

What is Hypothyroidism characterised by?

Answer 8

HIGH TSH levels and LOW T3 and T4 levels

Question 9

Why does Hypothyroidism occur?

Answer 9

Insufficient T3 and T4 produced from Thyroid gland results in the negative feedback loop to produce more TSH from the Anterior Pituitary gland.

Question 10

What are the common signs and symptoms of Hypothyroidism?

Answer 10

Slow speech, intolerance to cold, memory loss, depression, constipation, weight GAIN, dry skin, thin hair, BRADYcardia

Question 11

What are the treatments for Hypothyroidism (under-active thyroid)?

Answer 11

Levothyroxine (artificial T4) or Liothyronine (artificial T3, if Hypothyroidism is severe)

Question 12

What is the start dose for Levothyroxine?

Answer 12

50-100 mcg OM (25 mcg in patients 65+ yrs). Dose to be increased by 25-50mcg if TSH levels remain high. –> (1.6mcg/kg)

Question 13

What are the common signs and symptoms of Hyperthyroidism?

Answer 13

Palpitations, TACHYcardia, sweating, tremor, anxiety, diarrhoea, intolerance to heat, weight LOSS, numerous eye problems (exophthalmos (bulging of the eyes), swelling of eyelids, lid retraction, ophthalmoplegia (weakening of eye muscles) and diplopia (double vision)

Question 14

What are the symptomatic treatments for Hyperthyroidism (over-active thyroid)?

Answer 14

Propranolol for symptomatic treatment of tremor, palpitations and sweating

Question 15

Why is Bisoprolol not appropriate for symptomatic treatment of Hyperthyroidism?

Answer 15

This is because Bisoprolol is beta-1 selective (cardio selective) and would only relieve the patient of the palpitations and not the sweating and tremor.

Question 16

Why is Propranolol preferred over Bisoprolol for symptomatic treatment of Hyperthyroidism?

Answer 16

Because it is non-selective at beta receptors. It is more likely to control all of the symptoms. Bisoprolol is selective a beta-1 receptors in the heart.

Question 17

What anti-thyroid drugs are available for treatment of Hyperthyroidism?

Answer 17

First line: Carbimazole
Second line: Propylthiouracil (when patient cannot tolerate Carbimazole)

Question 18

What main counselling point is there for Carbimazole?

Answer 18

Be wary of any sore throats, easy bruising/bleeding. If you experience any of these, go to your GP immediately and stop taking Carbimazole.

Question 19

What other treatments are available for Hyperthyroidism?

Answer 19

Radioactive Iodine treatment, or Surgery (Thyroidectomy). Patients will require Levothyroxine treatment after these.

Question 20

What therapeutic monitoring parameters should be considered with Levothyroxine treatment?

Answer 20

Thyroid Function Tests and keeping an eye out for symptoms

Question 21

What toxic monitoring parameters should be considered with Levothyroxine treatment?

Answer 21

Thyroid Function Tests (risk of HYPERthyroidism) and symptoms (goitre, bulging eyes, tachycardia).

Question 22

What therapeutic monitoring parameters should be considered with Carbimazole treatment?

Answer 22

Thyroid Function Tests and symptoms

Question 23

What toxic monitoring parameters should be considered with Carbimazole treatment?

Answer 23

Thyroid Function Tests, symptoms and any signs of bone marrow suppression (neutropenia/ anaemia and sore throat/coughing.

Question 24

What is Primary Hypothyroidism?

Answer 24

Failure of the thyroid gland

Question 25

What is secondary Hypothyroidism?

Answer 25

Anterior Pituitary dysfunction resulting in low TSH levels

Question 26

What is tertiary Hypothyroidism?

Answer 26

Hypothalmic dysfunction resulting in low levels of TRH

Question 27

What is Hashimoto's thyroiditis?

Answer 27

An autoimmune condition where the body makes antibodies to thyroglobulin and causes hypothyroidism.

Question 28

What is Grave's disease?

Answer 28

Grave's disease is an autoimmune condition with a genetic predisposition, where the body makes thyroid-stimulating antibodies that mimic TSH, stimulating the TSH receptor in the thyroid gland.

Question 29

What is the mechanism of action of thioureylenes (Carbimazole)?

Answer 29

They inhibit the synthesis of thyroid hormone (T4). Inhibition of thyroperoxidase means that tyrosine residues on thyroglobulin are not iodinated.

Question 30

Why do people experience tremors and palpitations in Hyperthyroidism?

Answer 30

Because overstimulation of the thyroid gland (excess thyroid hormone) causes an up-regulation of beta-adrenergic receptors in heart and lungs.

Question 31

How is the thyroid hormone synthesised?

Answer 31

TSH binds to GPCRs on epithelial cells in thyroid gland which cause an uptake of iodide ions. The iodide ions (I-) are actively transported into the follicle cells in the Thyroid gland via the Na+/I- co-transporter. Iodide ions are converted into Iodine by thyroid peroxidase. Thyroglobulin then binds its many tyrosine residues to Iodine. Monoiodotyrosine and Diiodotyrosine are used to create T3 and T4 respectively.